Beta-catenin is a protein that in humans and is encoded by the CTNNB1 gene. In Drosophila, the homologous protein is called armadillo. Β-catenin is a subunit of the cadherin protein complex and has been implicated as an integral component in the Wnt signaling pathway.HMP SHUNT

The pentose phosphate pathway (also called Phosphogluconate Pathway, or Hexose Monophosphate Shunt [HMP shunt]) is a process that serves to generate NADPH and the synthesis of pentose (5-carbon) sugars.

Protein kinase A is a group of enzymes whose activity is dependent on the level of cyclic AMP in the cell.PKA is also known as cAMP-dependent protein kinase. Protein kinase A has several functions in the cell, including regulation of glycogen, sugar, and lipid metabolism. It is important in regulating cell cycle, along with the protein Cyclin.

Chromosome puffs are diffuse uncoiled regions of the polygene chromosome that are sites of RNA transcription. A Balbiani ring is a large chromosome puff.

Cyclic AMP or Cyclic Adenosine Monophosphate is the second messenger important in many biological actions at the cellular level. It is the chemical messenger is generated in the cell membrane from Adenosine triphosphate or ATP in response to a signal from the first messenger (Hormone). cAMP is used for intracellular signal transduction in many organisms conveying the cAMP dependent pathway.

Pinopodes are small, finger-like protrusions from the uterine endometrium. They appear between day 19 and day 21 of gestational age. This corresponds to a fertilization age of approximately 5 to 7 days, which corresponds well with the time of implantation. They only persist for 2 to 3 days. The development of them is enhanced by progesterone but inhibited by estrogens.

Polytene Chromosome

To increase cell volume, some specialized cells undergo repeated rounds of DNA replication without cell division called Endomitosis, forming a giant Polytene chromosome. Polytene chromosomes form when multiple rounds of replication produce many sister chromatids that remain synapsed together.

Q Banding

Quinacrine mustard, an alkylating agent, was the first chemical to be used for chromosome banding. T. Caspersson and his colleagues, who developed the technique, noticed that bright and dull fluorescent bands appeared after chromosomes stained with quinacrine mustard were viewed under a fluorescence microscope.

Central dogma of molecular biology

The central dogma of molecular biology was first enunciated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970.The central dogma deals with the detailed residue-by-residue

transfer of sequential information. It states that information cannot be transferred back from protein to either protein or nucleic acid. In other words, 'once information gets into protein, it can't flow back to nucleic acid.'

Chaperones

Chaperones are proteins that assist the non-covalent folding/unfolding and the assembly/disassembly of other macromolecular structures, but do not occur in these structures when the latter are performing their normal biological functions. The common perception that chaperones are primarily concerned with protein folding is incorrect. The first protein to be called a chaperone assists the assembly of nucleosomes from folded histones and DNA and such assembly chaperones, especially in the nucleus, are concerned with the assembly of folded subunits into oligomeric structures.

Contig

A Contig (from contiguous) is a set of overlapping DNA segments derived from a single genetic source. A Contig is also sometimes defined as the DNA sequence reconstructed from a set of overlapping DNA segments.

DNA polymerase

A DNA polymerase is an enzyme that assists in DNA replication. Such enzymes catalyze the polymerization of deoxyribonucleotides alongside a DNA strand, which they "read" and use as a template. The newly-polymerized molecule is complementary to the template strand and identical to the template's partner strand.

Initiatior (Inr) motif

The Initiatior (Inr) motif is a DNA transcription promoter that is similar in function to the Pribnow box (for prokaryotes) or the TATA box (for eukaryotes). It has the consensus sequence YYAN(T/A)YY,where Y stands for any pyrimidine (cytosine or thymine). Similarly to the TATA box, the Inr motif facilitates the binding of Transcription Factor II D (TBP).

LINEs

Long interspersed nuclear elements are long DNA sequences (>5kb) that represent reverse-transcribed RNA molecules originally transcribed by RNA polymerase II into mRNA (messenger RNA to be translated into protein on ribosomes).

Pair-Rule Gene

Pair-rule gene is a type of gene involved in the development of the segmented embryos of insects. Pair-rule genes are defined by the effect of a mutation in that gene, which causes the loss of the normal developmental pattern in alternating segments.

Reverse transcription

Reverse transcription is the process of making a double stranded DNA (deoxyribonucleic acid) molecule from a single stranded RNA (ribonucleic acid) template. It is called reverse transcription as it acts in the opposite or reverse direction to transcription. This idea was very unpopular at first as it contradicted the Central Dogma of Molecular Biology which states DNA is transcribed into RNA which is translated into proteins. However, in 1970 when the scientists Howard Temin and David Baltimore both independently discovered the enzyme responsible for reverse transcription, named reverse transcriptase, the possibility that genetic information could be passed on in this manner was finally accepted.

Ribozyme

A Ribozyme is an RNA molecule that catalyzes a chemical reaction. Many natural ribozyme catalyze either the hydrolysis of one of their own phosphodiester bonds, or the hydrolysis of bonds in other RNAs, but they have also been found to catalyze the aminotransferase activity of the ribosome.

Sigma factor

A sigma factor (σ factor) is a prokaryotic transcription initiation factor that enables specific binding of RNA polymerase to gene promoters. Different sigma factors are activated in response to different environmental conditions. Every molecule of RNA polymerase contains exactly one sigma factor subunit, which in the model bacterium Escherichia coli is one of those listed below. E. coli has at least eight sigma factors; the number of sigma factors varies between bacterial species. Sigma factors are distinguished by their characteristic molecular weights. For example, σ70 refers to the sigma factor with a molecular weight of 70 kDa.

SINEs

Short interspersed nuclear elements are short DNA sequences (<500 bases) that represent reverse-transcribed RNA molecules originally transcribed by RNA polymerase III into tRNA, rRNA, and other small nuclear RNAs. SINEs do not encode a functional reverse transcriptase protein and rely on other mobile elements for transposition.

TATA box

The TATA box (also called Goldberg-Hogness box) is a DNA sequence (cis-regulatory element) found in the promoter region of most genes in eukaryotes and Archaea. Considered to be the core promoter sequence, it is the binding site of either transcription factors or histones (the binding of a transcription factor blocks the binding of a histone and vice versa) and is involved in the process of transcription by RNA polymerase.

The Pribnow box

The Pribnow box (also known as the Pribnow-Schaller box) is the sequence TATAAT of six nucleotides (thymine-adenine-thymine-etc.) that is an essential part of a promoter site on DNA for transcription to occur in bacteria. It is an idealized or consensus sequence - that is, it shows the most frequently occurring base at each position in a large number of promoters analyzed; individual promoters often vary from the consensus at one or more positions. It is also commonly called the -10 sequence, because it is centered roughly 10 base pairs upstream from the site of initiation of transcription.

Cell signaling

Cell signaling is part of a complex system of communication that governs basic cellular activities and coordinates cell actions. The ability of cells to perceive and correctly respond to their microenvironment is the basis of development, tissue repair, and immunity as well as normal tissue homeostasis. Errors in cellular information processing are responsible for diseases such as cancer, autoimmunity, and diabetes. By understanding cell signaling, diseases may be treated effectively and, theoretically, artificial tissues may be yielded.

Cell surface Receptors

A  Receptor is a protein molecule, embedded in either the plasma membrane or the cytoplasm of a cell, to which one or more specific kinds of signaling molecules may attach. A molecule which binds to a receptor is called a ligand, and may be a peptide or other small molecule, such as a neurotransmitter, a hormone, a pharmaceutical drug, or a toxin. Each kind of receptor can bind only certain ligand shapes. Each cell typically has many receptors, of many different kinds.

Endocrine Disruptors

Endocrine disruptors are chemical substances that act on the endocrine system and disrupt its functions. The term Endocrine disruptor was introduced in the Wingspread Conference Centre; Wisconsin in 1991.The work of Theo Colborn showed that the environmental chemicals disturbed the development of endocrine system. Endocrine disruption refers to the fact that there is negative interference or permanent adverse consequences beyond the range of everyday fluctuations of hormone levels.

METAPLASIA

Metaplasia (Greek: "change in form") is the reversible replacement of one differentiated cell type with another mature differentiated cell type. The change from one type of cell to another is generally caused by some sort of abnormal stimulus. In simplistic terms, it is as if the original cells are not robust enough to withstand the new environment, and so they change into another type more suited to the new environment. If the stimulus that caused Metaplasia is removed or ceases, tissues return to their normal pattern of differentiation. Metaplasia is not synonymous with dysplasia and is not considered

carcinogenesis. It is also contrasted with heteroplasia, which is the abnormal growth of cytologic and histologic elements without a stimulus.

PYROGENS

Paracetamol is the safest drug used to control temperature. It is called as Antipyretic. When there is infection in the body, the WBC produces chemical called Pyrogens. The pyrogens are responsible for fever. Paracetamol inhibits the production of pyrogens and reduce body temperature. Paracetamol is the diethylated product of the active metabolite of Phenacetin which is now banned. Paracetamol is a para-amino phenol derivative which is N-acetyl-p-aminophenol.

Membrane Receptor Structure

The T cell receptor or TCR is a molecule found on the surface of T lymphocytes (or T cells) that is, in general, responsible for recognizing antigens bound to major histocompatibility complex (MHC) molecules.It is a hetero dimer  consisting of an alpha and beta chain in 95% of T cells, whereas 5% of T cells have TCRs consisting of gamma and delta chains. Engagement of the TCR with antigen and MHC results in activation of its T lymphocyte through a series of biochemical events mediated by associated enzymes, co-receptors, specialized accessory molecules and activated or released transcription factors.

Secondary messenger system

A secondary messenger system (also known as a second messenger system) is a method of cellular signaling, whereby a diffusable signaling molecule is rapidly generated/released which can then go on to activate effector proteins within the cell to exert a cellular response. Secondary messengers are a component of signal transduction cascades.

Assisted Reproductive Technology -ART

Assisted reproductive technology is the methods used to achieve pregnancy by artificial or partially artificial means. It is reproductive technology used primarily in infertility treatments. ART is also used in couples who are discordant for certain communicable diseases, i.e. AIDS, to reduce the risk of infection when a pregnancy is desired. The term also includes any reproductive technique involving a third party e.g. a sperm donor. There is yet no strict definition of the term. Usage of the ART mainly belongs in the field of reproductive endocrinology and infertility.

Bio-Electric Stimulation Therapy – BEST

It is also known as Micro Current Electrotherapy or MET. It is a specific electro therapy that gives small current into the body. The current is less than one milli ampere. BEST mimics the electrical stimulations of cells by the nerves. This increases the physiology of the cells. BEST has a positive effect on fatigue and chronic pain. BEST boosts energy levels of the cells and restores the homeostasis of the cells by increasing the production of ATP, Transmembrane transport, stimulation of fibroblasts etc.

BLAST- Basic Local Alignment Search Tool The BLAST is used to infer functional and evolutionary relationships between sequences as well as help identify members of gene families. The FASTA programs find regions of local or global similarity between Protein or DNA sequences, either by searching Protein or DNA databases, or by identifying local duplications within a sequence.

CHORDIN

Second organizer protein isolated from the clones of cDNA whose mRNAs were present in dorsalised, but not in ventralized embryo. It .is a polypeptide that dorsalizes the developing embryo by binding ventralizing TGFβ proteins such as Bone morphogenetic proteins. It may also play a role in organogenesis. There are five named isoforms of this protein that are produced by alternative splicing.

Cryopreservation

Cryopreservation is a process where cells or whole tissues are preserved by cooling to low sub-zero temperatures, such as (typically) 77 K or −196 °C (the boiling point of liquid nitrogen). At these low temperatures, any biological activity, including the biochemical reactions that would lead to cell death, is effectively stopped. However, when vitrification solutions are not used, the cells being preserved are often damaged due to freezing during the approach to low temperatures or warming to room temperature.

Decidualization

Decasualization succeeds pre decidualization if pregnancy occurs. This is an expansion of it, further developing the uterine glands, the zona compacta and the epithelium of decidual cells lining it. The decidual cells become filled with lipids and glycogen and take the polyhedral shape characteristic for decidual cells.

Fluorescence in Situ Hybridization – FISH

Fluorescence in situ hybridization (FISH) is the molecular cytogenetic technique that allows cytogeneticists to analyze chromosome resolution at the DNA or gene level. FISH can be performed on dividing (metaphase) and non-dividing (interphase) cells to identify numerical and structural abnormalities resulting from genetic disorders.

GIFT: Gamete Intra-Fallopian Transfer

GIFT involves placement of unfertilized eggs from the woman and her partner's sperm in the fallopian tubes of the woman with laparoscopy. GIFT can be used as an effective treatment for infertility of all causes except for women with infertility caused by tubal blockage or significant tubal damage or an anatomic problem with the uterus, such as severe intrauterine adhesions. It also should not be used for any significant male factor infertility   cases.

Insitu Hybridization

In situ hybridization (ISH) is a type of hybridization that uses a labeled complementary DNA or RNA strand (i.e., probe) to localize a specific DNA or RNA sequence in a portion or section of tissue (in situ), or, if the tissue is small enough (e.g. plant seeds, Drosophila embryos), in the entire tissue (whole mount ISH). DNA ISH can be used to determine the structure of chromosomes. Fluorescent DNA ISH (FISH) can, for example, be used in medical diagnostics to assess chromosomal integrity. RNA ISH (hybridization histochemistry) is used to measure and localize mRNAs and other transcripts within tissue sections or whole mounts.

MAJOR HISTOCOMPATIBILITY COMPLEX

Location and functions of MHC

A viral infected cell will express small fragments of viral protein on its surface to recognize by cytotoxic T cells. The antigen fragments are presented on the surface of the cell by a specialized group of molecules called MHC proteins. These are encoded in a set of genes called Major Histocompatibility Complex (MHC). The genes are located in the 5Th chromosome Major histocompatibility complex (MHC): Originally recognized as antigens responsible for graft rejection in incompatible hosts after transplantation. These are molecules that bind with processed antigens and are displayed on the surface of cells. MHC class I molecules are displayed on non-immune cells and MHC class II on antigen-presenting cells.

Nidation

The organic process by which the developing blasocyst attaches to the uterine lining. There are many conditions that must be satisfied in order for a successful implantation to take place. There is only a specific period of time during which implantation is possible; this is the "implantation window". A reason for this window is that if implantation does not occur at a certain time, then it signifies that something is wrong. And when there is a risk that something is wrong, there will most likely be a miscarriage rather than the continued gestation of a malformed fetus.

Nieuwkoop Center

Nieuwkoop Center is the Primary Organizer forming centre seen in the developing egg of some Amphibians. In Xenopus, the Nieuwkoop Center is the dorsal- and vegetal-most region. It gives rise to the Primary Organizer called Spemann-Mangold Organizer which is the region known as the d orsal   l ip of the   b lastopore (DLB) . Spemann and Mangold’s experiments found that the DLB dorsalizes surrounding tissue, thus forming the dorsal-ventral axis. In addition to dorsalizing surrounding tissue, the Primary Organizer fates overlying ectoderm as neural plate tissue; and is determined to be notochord tissue.

NOGGIN

First soluble organizer molecule isolated in 1992 by Smith and Harland. Noggin is a polypeptide that binds to members of the TGF-β super family of proteins. It is a Bone morphogenetic protein inhibitor. Noggin plays a key role in neurulation by inhibiting BMP4, along with other morphogens such as chordin and follistatin and inducing the formation of the neural plate. It plays a crucial role in bone development, by regulating the functions of BMP's. During the morphogenisis of organs such as the lungs, teeth and hair follicles, noggin helps to produce Lef1. Mouse knockout experiments show that noggin plays a role in neural tube fusion and joint formation.

Physical Gene Mapping

In physical mapping, the DNA is cut by a restriction enzyme. Once cut, the DNA fragments are separated by electrophoresis. The resulting pattern of DNA migration (i.e., its genetic fingerprint) is used to identify what stretch of DNA is in the clone. By analyzing the fingerprints, Contigs are assembled by automated or manual means into overlapping DNA stretches. Now a good choice of clones can be made to efficiently sequence the clones to determine the DNA sequence of the organism under study.

Pinopodes

Pinopodes are small, finger-like protrusions from the uterine endometrium. They appear between day 19 and day 21 of gestational age. This corresponds to a fertilization age of approximately 5 to 7 days, which corresponds well with the time of implantation. They only persist for 2 to 3 days. The development of them is enhanced by progesterone but inhibited by estrogens.

Snuppy

Snuppy (born April 24, 2005) is the world's first cloned dog. This Afghan Hound clone was created by Hwang Woo-Suk and his team of scientists at Seoul National University (SNU) in South Korea. The name "Snuppy" is a combination of "SNU" and "puppy."The researchers transferred 1,095 dog embryos into 123 females, inducing three pregnancies. One fetus miscarried, and one clone died of pneumonia after three weeks. A Labrador Retriever carried the third embryo to term. The team announced their success in cloning in August of 2005.

TISSUE GRAFTING

Autografts Any tissue transferred from one site to another in the same individual (iliac bone from the pelvis is commonly used to supplement the fusion mass). Tissue taken from one part of an individual organism's body and then moved or transplanted to another location within that same organism. Rejection is rarely (if ever) a problem since the donor and recipient are the same individual. Skin transplants are a common example.

Allograft Graft of a piece of tissue or organ from one individual to another of the same species Homograft: tissue or organ transplanted from a donor of the same species but different genetic makeup; recipient's immune system must be suppressed to prevent rejection of the graft

Isografts A graft of tissue between genetically identical individuals

Xenografts -zen´o-graft. A graft of tissue transplanted between animals of different species. Called also heterograft, heterologous graft, and heteroplastic graft. Xenotransplantation is the transplantation of living cells, tissues or organs from one species to another such as from pigs to humans. (See Medical grafting.) Such cells, tissues or organs are called Xenografts (xenotransplants). The term allo transplantation refers to a same-species transplant.

Graft retention – methods - To prevent tissue rejection drugs called ‘Immunosuppressants” are administered after the organ transplantation. The most commonly used drugs are Antimetabolites, Alkylating agents, Toxic antibodies etc. Radiation, Cyclosporin FK 506, Antilymphocyte globulins, Adrenal corticoids, Azothioprine etc are also used as Immunosuppressants. These drugs hinder the development of T lymphocytes.

Graft rejection – methods- Tissue rejection is due to cell mediated immune system of T cells of the recipient consider the transplanted organ as ‘Non self’. The process of rejection starts after 10-14 days of transplantation. This is indicated by the accumulation of T cells in the blood vessels of the transplanted organ. This prevents normal blood flow to the organ leading to its rejection. The MHC also stimulates the production

ZIFT

ZIFT: Stands for zygote intrafallopian transfer, a method used to treat infertility in which an egg fertilized in vitro (outside the body) is placed into a woman's fallopian tube. This technique is one used to overcome infertility, the inability of couples to produce offspring on their own.

EPITOPES AND HAPTENS

Epitope – A single antigenic determinant. Functionally it is the portion of an antigen which combines with the antibody .Antibody binds to a particular part of the antigen called epitope. A particular antigen has different epitopes. Antibodies are specific for the epitope rather than the whole complex

Hapten – A single molecule which act as an epitope but is incapable by itself of eliciting an antibody response. Become Immunogenic only if bound to a protein carrier. Used to produce immune response, production of polyclonal and monoclonal antibodies

MALNUTRITION DISEASES

Deficiency of one or more nutrients in the food for prolonged period leads to the appearance of diseases called malnutrition diseases. Kwashiorkor is a malnutrition disease caused by the deficiency of Proteins. It is characterized by stunted growth, mental retardation, thin legs, protruded belly etc. Marasmus is caused by the deficiency of Proteins and Calorie. It is characterized by flabby body, elevated ribs, weakness etc. Excess intake of food leads to Obesity characterized by overweight. Hypercholesterolemia is the high cholesterol level (150 – 250 mg / 100 ml blood) in the blood. It is due to excess intake of fatty food materials. Excess cholesterol leads to Arteriosclerosis, High blood pressure etc.

PACINIAN CORPUSCLES

Pacinian corpuscles are present in the skin to detect touch sensation. It has very large receptive area that receives vibratory sensation. It is onion like in appearance. Other receptors for pressure detection are Meissner’s corpuscles for Speed of stimulus application, Merkel’s for location of stimulus and Ruffni’s corpuscles for magnitude and duration of stimuli.

PROLACTIN

Prolactin is the only pituitary hormone which is directly inhibited by the Hypothalamus. Other hormones receive positive response through Releasing Factors-RF. Prolactin Inhibiting Factor – PIF – which is chemically Dopamine is produced from the hypothalamus. It inhibits the Prolactin. When the brain is transected, due to the absence of PIF, Prolactin amount increases. But other hormones like ACTH, GH, TH etc decrease.

Gap Gene

Gap gene is a type of gene involved in the development of the segmented embryos of some arthropods. Gap genes are defined by the effect of a mutation in that gene, which causes the loss of contiguous body segments, resembling a gap in the normal body plan. Each gap gene, therefore, is necessary for the development of a section of the organism.

Homeotic genes

Genes that affect embryo development by specifying the character of a body segment. The classic example is Antennapedia, a gene that, when mutated, causes a fruitfly to grow a leg in place of antenna. Homeotic genes are homeobox genes that are responsible for segment identity in metazoan organisms. Inappropriate expression of Homeotic genes will, in general, transform parts of the body into structures appropriate to other positions. An example would be the Antennapedia mutant of the fruit fly Drosophila, in which legs are found sprouting where antennae would normally be. Localized expression of Homeotic genes is controlled by upstream maternal proteins, gap genes, and pair rule genes in the developmental cascade.

Lamp brush chromosome

Lamp brush chromosome is a kind of Giant or Polytene chromosome found in the developing Oocytes of some Animals. It was discovered by Ruckert in 1892. The Lamp brush chromosome contains lateral loops and appears like a brush. Hence the name lamp brush chromosomes. It is found in the Oocytes of Sagitta, Sepia, Echinaster (Echinoderm), insects, sharks, amphibians, reptiles, and birds. Each lamp brush chromosome consists of a main axis and many lateral loops. The main axis of each chromosome is formed of 4 chromatids. The main axis contains a series of thickenings called chromomere. From each chromomere a pair of lateral loops one on each side. Each loop has an axial fibre. The axial fibre is the continuation of the chromonema of the main axis. Hence it contains DNA.

MITOCHONDIAL GENETICS

Mitochondrial genetics is the study of the genetics of the DNA contained in mitochondria. Mitochondria are small structures in cells that generate energy for the cell to use, and are hence referred to as the "powerhouses" of the cell.

Mitochondrial DNA (mtDNA) is not transmitted through nuclear DNA (nDNA), and in most multicellular organisms, virtually all mitochondria are inherited from the mother's ovum, as it is unusual for sperm cells to contribute mitochondria when fertilising ova.

Mitochondrial inheritance is therefore non-Mendelian, as Mendelian inheritance presumes that half the genetic material of a fertilized egg (zygote) derives from each parent.

Restriction Endonuclease

A restriction enzyme (or restriction Endonuclease) is an enzyme that cuts double-stranded or single stranded DNA at specific recognition nucleotide sequences known as restriction sites. Such enzymes, found in bacteria and archaea, are thought to have evolved to provide a defense mechanism against invading viruses. Inside a bacterial host, the restriction enzymes selectively cut up foreign DNA in a process called restriction; host DNA is methylated by a modification enzyme (a methylase) to protect it from the restriction enzyme’s activity. Collectively, these two processes form the restriction modification system. To cut the DNA, a restriction enzyme makes two incisions, once through each sugar-phosphate backbone (i.e. each strand) of the DNA double helix.

Retrotransposons

Retrotransposons (also called transposons via RNA intermediates) are genetic elements that can amplify themselves in a genome and are ubiquitous components of the DNA of many eukaryotic organisms. They are a subclass of transposon. They are particularly abundant in plants, where they are often a principal component of nuclear DNA. In maize, 49-78% of the genome is made up of retrotransposons. In wheat, about 90% of the genome consists of repeated sequences and 68% of transposable elements. In mammals, almost half the genome (45% to 48%) comprises transposons or remnants of transposons. Around 42% of the human genome is made up of retrotransposons while DNA transposons account for about 2-3%.

Gene Frequency

Gene frequency or Allele frequency is the proportion of all copies of a gene that is made up of a particular gene variant (allele). In other words, it is the number of copies of a particular allele divided by the number of copies of all alleles at the genetic place (locus) in a population. It can be expressed for example as a percentage. In population genetics, allele frequencies are used to depict the amount of genetic diversity at the individual, population, and species level. It is also the relative proportion of all alleles of a gene that are of a designed type.

Gene Pool

A gene pool is the complete set of unique alleles in a species or population. A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection. Meanwhile, low genetic diversity can cause reduced biological fitness and an increased chance of extinction. When all individuals in a population are identical with regard to a particular phenotypic trait, the population is said to be monomorphic. When the individuals show several variants of a particular trait they are said to be polymorphic.

Genetic polymorphism

Genetic polymorphism is the simultaneous occurrence in the same locality of two or more discontinuous forms in such proportions that the rarest of them cannot be maintained just by recurrent mutation.Genetic polymorphism is actively and steadily maintained in populations by natural selection, in contrast to transient polymorphisms where a form is progressively replaced by another. By definition, genetic polymorphism relates to a balance or equilibrium between morphs.

Founder Effect

The founder effect refers to the loss of genetic variation when a new colony is established by a very small number of individuals from a larger population. It was first fully outlined by Ernst Mayr in 1952, using existing theoretical work by those such as Sewall Wright. As a result of the loss of genetic variation, the new population may be distinctively different, both genetically and phenotypically, from the parent population from which it is derived. In extreme cases, the founder effect is thought to lead to the speciation and subsequent evolution of new species.

Genetic Drift

The genetic drift or allelic drift is the evolutionary process of change in the allele frequencies (or gene frequencies) of a population from one generation to the next due to the phenomena of probability in which purely chance events determine which alleles (variants of a gene) within a reproductive population will be carried forward while others disappear. Especially in the case of small populations, the statistical effect of sampling error during random sampling of certain alleles from the overall population may result in an allele, and the biological traits that it confers, to become more common or rare over successive generations, and result in evolutionary change over time.

The concept of Genetic drift was first introduced by Sewall Wright in the 1920s, and is now held to be one of the primary mechanisms of biological evolution. It is distinct from natural selection, a non-random evolutionary selection process in which the tendency of alleles to become more or less widespread in a population over time is due to the alleles' effects on adaptive and reproductive success.

Gene Pool

The gene pool is the complete set of unique alleles in a species or population. A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive. Meanwhile, low genetic diversity can cause reduced biological fitness and an increased chance of

extinction. When all individuals in a population are identical with regard to a particular phenotypic trait they are known as Monomorphic.

Hardy-Weinberg Principle

Hardy-Weinberg principle states that when no evolution occurs in a population the allele and genotype frequencies do not change from one generation to the next. No evolution refers to no mutation, no gene flow, no natural selection, and no genetic drift. To be in equilibrium two more assumptions need to be made that random mating occurs and there are discrete, non-overlapping generations.

Speciation

Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages.Whether genetic drift is a minor or major contributor to speciation is the subject of much ongoing discussion. There are four geographic modes of speciation in nature, based on the extent to which speciating populations are geographically isolated from one another: allopatric, peripatric, parapatric, and sympatric. Speciation may also be induced artificially, through animal husbandry or laboratory experiments. Observed examples of each kind of speciation are provided throughout.

Chromosome Banding

It is the cytological technique in which the metaphase chromosome is stained using appropriate stains to see the banding pattern of the chromosome. Chromosome band is the transverse band produced on the chromosomes by differential staining techniques. Depending on the particular staining technique, the bands are alternating light and dark or fluorescent and non fluorescent.

GenBank

The GenBank sequence database is the open access database. It is the annotated collection of all publicly available nucleotide sequences and their protein translations. The GenBank is produced at National Center for Biotechnology Information-NCBI- as part of the International Nucleotide Sequence Database Collaboration. GenBank receive sequences produced in laboratories throughout the world. GenBank contains the data of over 65 billion nucleotide bases.

Human Cytome project

Cytomes are the cellular systems, subsystems, and functional components of the body. The cytome is the collection of the complex and dynamic cellular processes (structure and function) underlying physiological processes. It describes the structural and functional heterogeneity of the cellular diversity of an organism. The study of Cytome is called Cytomics.

Molecular Cloning

Molecular cloning refers to the procedure of isolating a defined DNA sequence and obtaining multiple copies of it in vitro. Cloning is frequently employed to amplify DNA fragments containing genes, but it can be used to amplify any DNA sequence such as promoters, non-coding sequences, chemically synthesized oligonucleotide and randomly fragmented DNA. Cloning is used in a wide array of biological experiments and technological applications such as large scale protein production.

Electroencephalography (EEG)

EEG is the recording of electrical activity along the scalp produced by the firing of neurons within the brain. In clinical contexts, EEG refers to the recording of the brain's spontaneous electrical activity over a short period of time, usually 20-40 minutes, as recorded from multiple electrodes placed on the scalp. In neurology, the main diagnostic application of EEG is in the case of epilepsy, as epileptic activity can create clear abnormalities on a standard EEG study. A secondary clinical use of EEG is in the diagnosis of coma and encephalopathies. EEG used to be a first-line method for the diagnosis of tumors, stroke and other focal brain disorders, but this use has decreased with the advent of anatomical imaging techniques such as MRI and CT.

Electroporation

Electroporation is the artificial means of DNA transfer into the cells using an electrical field. It is defined as the use of electrical field to reversibly form micropores in the cell membrane. It is relatively new, simple and rapid technique to introduce DNA in a wide variety of cells. This technique is based on the original observation of Zimmermann in 1983 that high current pulses can induce cell membranes to fuse.

ESEM

The invention of Environmental SEM (ESEM) during 1980s allowed samples to be observed in low-pressure gaseous environments of 1-50 Torr and high relative humidity. This was made possible by the development of a secondary-electron detector capable of operating in the presence of water vapour and by the use of pressure-limiting apertures with differential pumping in the path of the electron beam to separate the vacuum regions around the gun and lenses from the sample chamber. The first commercial ESEMs were produced by the ElectroScan Corporation in USA in 1988.

ESEM uses a proprietary Environmental Secondary Detector (ESD) which can function in non-vacuum environment instead of Everhart-Thornley (ET) detector used in SEM. The ESD uses the principle of gas ionization. By applying a positive potential of a few hundred volts to the detector, the secondary electron emitted by the sample when interacts with electron beam is attracted to detector. As the electrons accelerate in the detector field, they collide with gas molecules. The resulting ionizations create additional electrons, amplifying original secondary electron signal, and positive ions. The detector collects secondary electron signal and passes it directly to an electron amplifier. In nonconductive samples the positive ions created in gas ionization process are attracted to the sample surface and they effectively suppress charging artifacts.

Functional MRI or functional Magnetic Resonance Imaging (fMRI) is a type of specialized MRI scan. It measures the haemodynamic response related to neural activity in the brain or spinal cord of humans or other animals. It is one of the most recently developed forms of neuroimaging. Since the early 1990s, fMRI has come to dominate the brain mapping field due to its low invasiveness, lack of radiation exposure, and relatively wide availability.

GENE MAPPING

Gene mapping refers to one of two different ways of definitively locating the gene on a chromosome. The first type of gene mapping is also called genetic mapping. Genetic mapping refers to the use of linkage analysis to determine how two genes on a chromosome relate in their positions. Physical mapping, the other type of gene mapping, locates genes by their absolute positions on a chromosome using any technique available. Once a gene is located, it can be cloned, its DNA sequence determined, and its molecular product studied.

Light Microscopy

Leeuwenhoek developed the first powerful microscope

Chromatic aberration

Chromatic aberration is caused by a lens having a different refractive index for different wavelengths of light (the dispersion of the lens).Longitudinal and lateral chromatic aberration of a lens is seen as "fringes" of color around the image, because each color in the optical spectrum cannot be focused at a single common point on the optical axis.

Numerical aperture

Numerical aperture (NA) is the light gathering ability of the Lens

The numerical aperture of an optical system such as an objective lens is defined by

where n is the index of refraction of the medium in which the lens is working (1.0 for air, 1.33 for pure water, and up to 1.56 for oils)

θ is the half-angle of the maximum cone of light that can enter or exit the lens.

In microscopy, NA is important because it indicates the resolving power of a lens.

The size of the finest detail that can be resolved is proportional to λ/NA, where λ is the wavelength of the light.

A lens with a larger numerical aperture will be able to visualize finer details than a lens with a smaller numerical aperture. Lenses with larger numerical apertures also collect more light and will generally provide a brighter image.

NA of the condenser lens control resolution of the objective

Lm = λ / NA of objective + NA of condenser

NA of oil immersion objective is 1 to 1.35

Lm = 0.61 λ / 1.3 = 0.5 λ

In air NA is less than 1.

The practical way to increase NA is to increase refractive index of the medium

Refractive index of Air is 1. Optical lenses less than 1.6. Oil 1.4

Resolution

Optical resolution describes the ability of an imaging system to resolve detail in the object that is being imaged. Lens resolution is the ability of a lens to resolve detail is usually determined by the quality of the lens but is ultimately limited by diffraction.

A measure of the resolving power of a lens is given by its numerical aperture, NA:

where λ is the wavelength of light. From this it is clear that a good resolution (small δ) is connected with a high numerical aperture.

The ability to distinguish two close points as distinct points is called Resolving power or Limit of resolution

Limit of resolution of light microscope Lm = 0.16 / NA

Limit of resolution of unaided human eye is 100 micrometer

Limit of resolution of optical microscope is 0.25 micrometer

Limit of resolution is inversely proportional to the wavelength of light.

Lm is determined using the Abbe equation Lm = 0.61λ / NA

Lm is the limit of resolution; λ is the wavelength of light and NA numerical aperture

Lm can be improved by

1. Using shorter wavelength of light

2. Increasing refractive index of the medium (n) or Sine of semi angle of light (Sin )

Sin is the sine of angle of light passing into the objective from the specimen

It can be higher than 1. Because Sin 90 degree is equal to 1, while Sine 70 degree = 0.94

For best objective lens semi angle is 70 degree

Resolution of a microscope is roughly ½ the wavelength of the illumination light

Average wavelength of light is 500 – 600 nm which gives a resolution of 250 – 300 nm or 0.25 – 0.3 micrometer.

The visible light of shortest wavelength is around 426 nm giving an Lm of 200 nm or 0.2 micrometer

So superior microscopes uses blue light or blue filters

Magnification

Enlargement or Ratio of size of an object obtained under the microscope and its actual size seen with the naked eye

Magnification equals to the magnification of the objective lens multiplied by the magnification of the eye piece

Working Distance

Distance between the object (or cover glass) and the surface of the front lens of objective

Low power objectives (10X, 45X) have large working distance and smaller NA

High power objectives (100X) have short working distance and large NA

Magnification is also a number describing by which factor an object was magnified. When this number is less than one it refers to a reduction in size, sometimes called Minification.

Depth of Field

In optics, particularly as it relates to film and photography, the depth of field (DOF) is the portion of a scene that appears sharp in the image.

The DOF is determined by the subject distance the lens focal length, and the lens f-number (relative aperture)

Real Image

A real image is a representation of an actual object (source) formed by rays of light passing through the image. If a screen is placed in the plane of a real image the image will generally become visible.

Virtual Image

A virtual image is an image in which the outgoing rays from a point on the object never actually intersect at a point.

Wavelength

Wavelength is the distance between repeating units of a propagating wave of a given frequency.

It is commonly designated by the Greek letter lambda (λ). Examples of wave-like phenomena are light, water waves, and sound waves.

The wavelength is related to the frequency by the formula: wavelength = wave speed / frequency.

Wavelength is therefore inversely proportional to frequency.

Higher frequencies have shorter wavelengths. Lower frequencies have longer wavelengths, assuming the speed of the wave is the same.

Magnetic resonance imaging (MRI),

Magnetic resonance imaging (MRI), or nuclear magnetic resonance imaging (NMRI), is primarily a medical imaging technique most commonly used in radiology to visualize the structure and function of the body. It provides detailed images of the body in any plane. MRI provides much greater contrast between the different soft tissues of the body than computed tomography (CT) does, making it especially useful in neurological (brain), musculoskeletal, cardiovascular, and oncological (cancer) imaging. Unlike CT, it uses no ionizing radiation, but uses a powerful magnetic field to align the nuclear magnetization of (usually) hydrogen atoms in water in the body. Radiofrequency fields are used to systematically alter the alignment of this magnetization, causing the hydrogen nuclei to produce a rotating magnetic field detectable by the scanner. This signal can be manipulated by additional magnetic fields to build up enough information to construct an image of the body.

MEDICAL INSTRUMENTS

Non Invasive Techniques Techniques and instruments which are free from risk of injury to the body

Einthoven Father of Electrocardiography

Echocardiography Also called Sonography – Used to image Aorta, Heart valves, Heart wall etc. It is also used to record blood flow velocity and blood turbulence

Vector cardiography To analyze Q wave and Intra ventricular conduction abnormalities

SQUID Super conducting Quantum Interference Device. Eg. Magneto encephalograph.

MET Magneto Encephalographic Technique and SQUID are used to give information about the health of various parts of the brain. It can be used to study weaker magnetic fields for the brain.

Auto Analyzer Fully computerized, automatic instrument which can analyze qualitatively and quantitatively various bio chemicals present in body fluids.

Tomography Technique of development of three dimensional impression of internal organs imaging of different layers. Tomography can indicate cysts, tubercular foci , calculi , cancers etc.

CT Scanning Uses short X rays for radiographic imaging of internal organs. CT scanning employs more than 30,000, 2-4 mm beams of X-rays. It uses low level X-rays so that radiation damage is little. CT scanning is used to diagnose parts like abdomen, chest, spinal cord, brain, tumors, oedema etc. It is commonly used to investigate the brain after a Stroke.

CAT Computerized Axial Tomography. Uses X- rays to study internal parts in the skull. CAT is now replaced by CT scanning.

PET Positron Emission Tomography. Used to measure metabolic rate, regional blood volume, blood flow , area of abnormalities. Special centers of the brain, like colour processing in visual cortex of humans can be detected by PET.PET uses positron emitting radio isotopes like Carbon eleven.

MRI Magnetic Resonance Imaging. Uses strong magnetic field for generating resonance and low radio frequency in protons present in the body. The most common proton is the H1 nuclei present in water molecules. MRI is superior than CT because

1. It uses non ionizing radiations2. It gives 2 or 3D pictures.3. Image is obtained from any plane.4. Provides better information about tumors and infections.MRI scanning cannot be performed in patients carrying Ferro magnetic devices like artificial pace makers, metal cardiac valves etc because the MRI magnets will interfere with this. In such a situation CT scanning is recommended.

Sonography Also called Echography. It uses ultrasound to produces images of the internal organs. Ultrasound is beyond human hearing power or above 20,000 Hz or 20 kHz. Visual record is called Sonogram or Echogram. Ultra sound is produced through piezoelectric effect. Ultrasound is produced by lead zirconate. Sex determination of Foetus using Sonography is banned in 1994 under prenatal diagnostic act

Doppler ultrasound

Scanning Used to scan blood flow in vessels, blood clots , and heart abnormalities.

HEI Hall Effect Imaging. Used to pinpoint diseased tissues like cancerous tissue.

Pace maker Devised by Greatbach and Chardack in 1960. Pace maker has a pulse generating device having a long lasting Lithium halide cell. Pace makers may be External pace maker, Epicardial pace maker, Endocardial pace maker, Permanent pace maker etc. Pace maker is an implant.

LASER Used to detect gall bladder and kidney stones. Laser is a form of monochromatic light. LASER is also used in surgery, to break chromosomes in genetic engineering etc.

Intra aortic balloon pump Improve blood supply to heart muscles after a clot. It is used to save life in emergency conditions by restoring the functions of organs. The devices of intra aortic balloon pump are

1. Implants like artificial heart valve , arteries2. Disposables like oxygenators, blood bags etc.3. External prosthetics like artificial foot.It assists heart in pumping of blood.

Angioplasty Used to remove bocks in the coronary artery.

A balloon is used to remove the blocks. A contrasting

dye is injected to locate the block and then the

Balloon is inflated to clear the path of blood flow.

First coronary angioplasty was done in 1977.

Coronary angioplasty is also called as PTCA

(Percutaneous Transluminal Coronary Angioplasty)

It is also called Baloon Procedure.

Angiography or

Arteriography A radio opaque contrast medium is used for the study of heart walls, valves, atria, ventricles etc.

Artificial Arteries Vascular grafts or arteries made of Dacron (fibrous plastic or Terylene) or Teflon (polytetra fluro ethylene). Vascular graft is required in Aneurysm.

Heart Lung bypass Instrument used during open heart surgery. Roller pump takes the function of heart and Oxygenator takes the function of lung

Blood bag Used to store blood, separation of components of blood and transfusion of blood.

Artificial blood Perflurocarbon can function as blood.

Cyclopean Also called Biological fluid connector. Blood purifying device.

Laennec Invented Stethoscope

Phonocardiogram Instrument used to amplify heart sounds.

Keratoplasy Transplanting of cornea. It is safe because it will

not produce immune response due to the

lack of blood in the cornea.

Artificial valve Heart valve made up of metal or rubber. Person carrying artificial valve in the heart should have to take small doses of Anticoagulant daily to preventing clot in the valve.

cDIVA It is the Gene for human growth

Thermometer Discovered by Galileo in 1593.

Defibrillator Used to reduce fibrillation of heart by giving mild electric shock.

Haemometer Used to measure the amount of haemoglobin per 100 ml blood.

Bertholt method Quantitative measurement of Urea in blood plasma or serum. Blood urea will decrease in early pregnancy.

Barium X ray Used to investigate digestive tract.

Air encephalography X ray test of the brain parts that contain fluid.

NMR Nuclear Magnetic Resonance is the method used to map internal organs including molecular structure. It completely avoids the use of ionizing radiations. It uses radio frequency in a controlled magnetic field. Resonance of Hydrogen in the water molecule and their energy release is the basis of NMR.

Myoelectric arm Used to move prosthetic hand and wrist.

Peritoneal dialysis Used to remove fluid from peritoneum. In peritoneal dialysis, dialysate pass in to abdominal cavity.

RBE Relative Biological Effectiveness. It is related to radiation dose

Haemocytometer Used to counting leucocytes.

Prosthesis Implantation of artificial body parts Eg. Jaipur (Rajasthan) Foot. Sethi is famous for Jaipur foot

Patch Clamp Technique

Patch Clamp Technique is a laboratory technique in electrophysiology that allows the study of single or multiple ion channels in cells. This discovery made it possible to record the currents of single ion channels for the first time, proving their involvement in fundamental cell processes such as action potential conduction. Erwin Neher and Bert Sakmann developed the patch clamp in the late 1970s and early 1980s.They received the Nobel Prize in Physiology and Medicine in 1991 for this work. Patch Clamp technique can be applied to a wide variety of cells, but is especially useful in the study of excitable cells such as neurons, cardiomyocytes, muscle fibers and pancreatic beta cells. It can also be applied to the study of bacterial ion channels in specially prepared giant spheroplasts.

Positron emission tomography (PET)

Positron emission tomography (PET) is a nuclear medicine imaging technique which produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule. Images of tracer concentration in 3-dimensional space within the body are then reconstructed by computer analysis. In modern scanners, this reconstruction is often accomplished with the aid of a CT X-ray scan performed on the patient during the same session, in the same machine.

Plasmon Resonance

The excitation of surface Plasmons by light is known as a Surface Plasmon Resonance or SPR. This is observed in nanometer-sized metallic structures. Surface Plasmons, are surface electromagnetic waves that propagate in a direction parallel to the metal or dielectric interface .This phenomenon is the basis of many standard tools for measuring adsorption of material onto planar metal (typically gold and silver) surfaces or onto the surface of metal nano particles.

Q Banding

Quinacrine mustard, an alkylating agent, was the first chemical to be used for chromosome banding. T. Caspersson and his colleagues, who developed the technique, noticed that bright and dull fluorescent bands appeared after chromosomes stained with quinacrine mustard were viewed under a fluorescence microscope. Quinacrine dihydrochloride was subsequently substituted for quinacrine mustard. The alternating bands of bright and dull fluorescence were called Q bands. Quinacrine-bright bands were composed primarily of DNA that was rich in the bases adenine and thymine, and Quinacrine-dull bands were composed of DNA that was rich in the bases guanine and cytosine.

SCANNING ELECTRON MICROSCOPE (SEM)

The scanning electron microscope (SEM) is a type of electron microscope that images the sample surface by scanning it with a high-energy beam of electrons in a raster scan pattern. The electrons interact with the atoms that make up the sample producing signals that contain information about the sample's surface topography, composition and other properties such as electrical conductivity.

The types of signals made by an SEM can include secondary electrons, back scattered electrons, characteristic x-rays and light (cathodoluminescence). These signals come from the beam of electrons striking the surface of the specimen and interacting with the sample at or near its surface. In its primary detection mode, secondary electron imaging, the SEM can produce very high-resolution images of a sample surface, revealing details about 1 to 5 nm in size. Due to the way these images are created, SEM micrographs have a very large depth of focus yielding a characteristic three-dimensional appearance useful for understanding the surface structure of a sample. This great depth of field and the wide range of magnifications (commonly from about 25 times to 250,000 times) are available in the most common imaging mode for specimens in the SEM, secondary electron imaging, such as the micrograph taken of pollen shown to the right. Characteristic x-rays are the second most common imaging mode for an SEM. X-rays are emitted when the electron beam removes an inner shell electron from the sample, causing a higher energy electron to fill the shell and give off energy. These characteristic x-rays are used to identify the elemental composition of the sample. Back-scattered electrons (BSE) that come from the sample may also be used to form an image. BSE images are often used in analytical SEM along with the spectra made from the characteristic x-rays as clues to the elemental composition of the sample.

Single-unit recording

Single Unit Recording is the use of an electrode to record the electrophysiological activity (action potentials) from a single neuron. The electrode introduced into the brain of a living animal will detect electrical activity that is generated by the neurons adjacent to the electrode tip. If the electrode is a microelectrode, with a tip size of 3 to 10 micrometers, the electrode will often isolate the activity of a single neuron. The activity consists of the voltages generated in the extra cellular matrix by the current fields outside the cell when it generates an action potential. Recording in this way is generally called "single-unit" recording. The recorded action potentials look very much like the action potentials that are recorded intracellularly, but the signals are very much smaller (typically about 0.1 mV).

TRANSMISSION ELECTRON MICROSCOPE (TEM )

Transmission electron microscopy (TEM) is a microscopy technique whereby a beam of electrons is transmitted through an ultra thin specimen, interacting with the specimen as it passes through it. An image is formed from the electrons transmitted through the specimen, magnified and focused by an objective lens and appears on an imaging screen, a fluorescent screen in most TEMs, plus a monitor, or on a layer of photographic film, or to be detected by a sensor such as a CCD camera. The first practical transmission electron microscope was built by Albert Prebus and James Hillier at the University of Toronto in 1938 using concepts developed earlier by Max Knoll and Ernst Ruska.

Agrobacterium tumefaciens

It has the ability to transfer and stably integrate foreign DNA into plant genome. Nif genes are tied to T1 plasmid and are allowed to integrate into genome of non-leguminous plants.

Azospirillum lipoferumNitrogen fixing bacteria present in the roots of Brazilian grasses and Maize. Scientists are trying to associate Azospirillum with cereals to reduce the use of chemical pesticides.

Penicillin

Antibiotic obtained from Penicillium notatum and Penicillium chrysogenum. Penicillin is a broad spectrum antibiotic. It prevents wall formation in bacteria and kills them.

Aspergillus niger

It is used in commercial preparation of citric acid from sugar beet and sugarcane molasses. It can convert 40% of sucrose to citric acid.

Embryo rescue technique

Technique used to prevent the death of hybrid embryos. The technique involves excision and growth of hybrid embryo in a culture on a nutrient medium. It helps to produce hybrids that are disease resistant.

Adaptive radiation

A phenomenon in evolution. It is the emergence of numerous species from a common ancestor introduced into an environment presenting a diversity of new opportunities and problems.

Allosteric siteIt is a specific site on the enzyme molecule. It is different from the active site. Molecule that binds to the Allosteric site change the shape of the active site making the enzyme either more or less receptive to the substrate.

Alpha diversityIt is defined as the diversity of organisms sharing the same community or habitat. A combination of species richness and evenness is used to represent alpha diversity.

Alpha helix

It represents the coiling form of polypeptide. The spiral shape of the protein is due to alpha helix coiling. Alpha helix is due to the formation of hydrogen bonds.

AmphidiploidIt is a tetraploid individual having 2 sets of chromosomes derived from two species. It is a form of allotetraploid.

Apical dominanceIt occurs during plant growth. Concentration of growth occurs at the tip of the shoot and the terminal bud partially inhibits the growth of axillary bud.

AutoradiographyIt is the method used to localize radioactive atoms in microscopic preparations of biological materials by exposing a photographic film emulsion to radioactive atoms incorporated in the biological specimen.

BACBacterial Artificial Chromosome. It consists of F plasmid of bacteria and can be used for transferring eukaryotic genes.

Balanced polymorphismIt is a type of polymorphism in which the frequencies of the coexisting forms do not change noticeably over many generations.

Bacillus thuringienesisIt is the soil bacterium produces a crystal protein called Cry protein in its spores which is toxic to larvae of certain insects. The gene encoding Cry protein is called cry gene and has been isolated and efforts are being made by scientists to transfer this gene into Chick pea and other pulses to protect them from severe damaged caused by insect pests.

Biopatency

Patency is a right given officially to an inventor to make or sell his/her invention and to prevent others from copying it. Countries like USA, Japan and European union award Biopatency for strains of microorganisms, cell lines, genetically modified plants and animals, DNA sequences, biotechnology products, procedures etc.

BiopiracyIt is the unauthorized use of patent resources by organizations and multinational companies of other nations. For example, the patent claimed by USA for the Basmati rice whose germplasm originally belong to India. The protein Brazzein from West African plant Pentadipiandra brazeana which is a low calorie sweetner has been patented in the USA.

BiowarThis involves the use of biological weapons against humans, crops and animals. Biological warfare involves bioweapon agents or toxins which attack humans, crops and animals and its use in war has been dated back to 5th century B.C. Bioweapon agents are contained in the containers and delivered as powders, sprays etc. Some of the potent pathogens used in biowarfare are Anthrax, Small pox, Botulinum pathogens.

Bioethics

It involves the set of standards that are used to regulate and monitor our activities in relation to biological world. Biotechnology has greatly exploited the biological world and there are several bioethical concerns which include over use, disrespect given to plants and animals and also the risk involved in the experiments.

Biological magnificationIt is a trophic process in which retained substances become more concentrated with each link in the food chain.

BioremediationIt is the use of microorganisms for the removal of pollutants.

Blood-Brain barrierThis is a specialized capillary arrangement in the brain that restricts the passage of most substances into the brain, thereby preventing dramatic fluctuations in the brain’s environment.

Biological Oxygen DemandIt is the quantitative expression of the oxygen depleting impact. It is an expression of how much oxygen is needed for microorganisms to oxidize their organic matter.

Bottle neck effectGenetic drift resulting from reduction of a population, typically by natural disaster, such that the surviving population is no longer genetically representative of the original population.

c-DNA

It is a duplex DNA complementary to m RNA synthesized from it by reverse transcription. It lacks introns because there is no introns in m RNA. C DNA is called complementary DNA.

Cell mediated immunityThe type of immunity that functions in defense against fungi, protests, bacteria and viruses in side host cells and against tissue transplants with highly specialized cells that circulates in the blood and lymphoid tissues.

ChaparrelA scrub land biome of dense, spiny, evergreen shrubs found along coasts where Cold Ocean currents circulate off shore, characterized by mild, rainy winters and long, hot, dry summers.

ChemiosmosisThe ability of certain membranes to use chemical energy to pump hydrogen ions and then harness the energy stored in the Hydrogen ion gradient to drive cellular work including ATP synthesis.

Co factorAny non-protein molecule or ion that is required for the proper functioning of an enzyme. Co factors can be permanently bound to the active site or may bind loosely with the substrate during catalysis

Competitive exclusion principleThe concept that when the populations of two species compete for the same limited resources, one population will use the resources more efficiently and have a reproductive advantage that will eventually lead to the elimination of the other population.

Complement systemA group of at least 20 blood proteins that cooperate with other defense mechanisms, may amplify the inflammatory response, enhance phagocytosis or directly lyses pathogens; activated by the onset of the immune response or by surface chemicals on microorganisms.

Convergent evolutionThe independent development of similarities between species as a result of their having similar ecological roles and selection process.

Corpus luteumSecreting tissue in the ovary that formed from the collapsed follicle after ovulation and produces progesterone.

Counter current exchange

The opposite flow of adjacent fluids that maximizes transfer rates. For example, blood in the gills flows in the opposite direction in which water passes over the gills, maximizing oxygen uptake and carbon dioxide loss.

Double Bohr EffectFoetal hemoglobin takes oxygen from mother hemoglobin through the placenta due to double Bohr Effect. Foetal hemoglobin dissociation curve shifts to left. Foetal hemoglobin is a tetramer having two alpha chains and two gamma chains. So HbF is insensitive to a shift due to 2-3 DPG and the curve is Sigmoid.

Oxygen dissociation curveIt is a graph that shows the percent saturation of hemoglobin at various partial pressures of oxygen. Commonly a curve may be expressed with P50 value. This value represents the pressure at which the erythrocytes are fifty percent saturated with oxygen. The purpose of the oxygen dissociation curve is to show the equilibrium of oxyhemoglobin and non- bonded hemoglobin.

SurfactantIt is a lipid surface tension lowering agent present in the lining of alveoli. It is a mixture of Dipalmitoyl Phosphotidyl Choline (DPPC), other lipids and proteins secreted by the type II alveolar epithelial cells. Surfactant reduces the surface tension in the fluid on the surface of alveoli, allowing them to expand at first breath and remain open there after.

2-3 DPG

2-3 Diphospho glycerate is a highly anionic organic phosphate created in the RBC, during glycolysis. It binds to hemoglobin and reduces the oxygen affinity. This is essential to unload oxygen in the tissue capillaries. In the absence of DPG, body makes more RBC. The RBC membrane become weak and RBC become irregularly shaped and hemolyse.

Gene bank

Gene bank or Gene library is the collection of cloned genes, frequently comprising cells of the gene from a particular species. Such libraries may consist of genomic sequences or DNA sequences, the latter having being made from messenger RNA and intron sequences.

Transgenic organismsOrganisms that has become transformed following the introduction of new DNA into its genome is called transgenic organism. Transgenic crop plants contain a gene or genes which have been artificially inserted instead of plant acquiring them through pollination. The inserted gene sequence is called Transgene may come from another unrelated plant or from a completely different species. For example, Bt Corn with gene from Bacillus thuringienesis, resistant to over ripening of Tomato.

Transgenic animals have novel genes obtained from outside. For example, Plasminogen activator in milk (Goat). Transgenic microbes are being used in industry for producing different bio chemicals and various functions. For example, Pseudomonas putida has been changed by introducing Plasmids of different strains for Alcoholic fermentation.

Bt Cotton, a transgenic crop variety, has been introduced in India. The Bt cotton variety contains a foreign gene obtained from Bacillus thuringienesis. This bacterial gene, introduced genetically into the cotton seeds protects the plant from Bollworm, a major pest of cotton. Bt cotton requires only 2 sprays of pesticide while the normal variety requires 8 sprays. According to Indian Council of Agricultural Research (ICAR), India uses about half of its pesticides on cotton to fight against Bollworm menacle. Use of Bt cotton has led to a 3% - 27% increase in cotton yield in countries where it is grown

Gene transfer techniquesUsed to transfer genes from one organism to another

1. Agrobacterium mediated gene transfer2. Direct gene transfer using Biolistics gun, Electroporation, Microinjection etc.

Transgenic plantsThe plants which carry additional stably integrated and expressed foreign genes transferred from other genetic sources are called as transgenic plants.

Agrobacterium mediated transferThe most common techniques used to transfer genes to Dicotyledonous plants using Agrobacterium. Cereals are difficult to transform through Agrobacterium because they do not have the proper wound response, a necessary requirement for transformation.

Transgenic vegetables

First transgenic plant Flavr Savr- delayed ripening tomato – introduced by Calgene Inc.

USA in 1994.

Cherry, Endless summer (tomato) – contains Bt protein gene against fruit borer.

Freedom II Squash resistant to water melon mosaic virus

New leaf (Potato) resistant to Colorado beetle (Leptinotarsa decemlineata)

AmAl Amaranth

Parthenocarpy fruits Seed less fruits

Golden rice with high Vit. A content

Biological magnificationIt is the process whereby certain substances such as pesticides or heavy metals move up the food chain, toxins build up a successive link of the food chain. It works their way into river or lakes and is eaten by aquatic organisms such as fish which in turn are eaten by large birds, animals or humans. The substance becomes concentrated in the chain. It is like a magnifying glass that makes things look bigger. Biological magnification makes toxin get bigger and stronger in the ecosystem.

Eg. 1 Some pesticides are considered as Environmental Estrogens. These chemicals interfere with sex hormones and cause decreases sperm counting, breast cancer, testicular cancer, mis carriage etc. Methoxyclor, Atrazine, Benomyl are examples.

Eg. 2 Beetals may have very low level of fat soluble pesticides, but the pesticides will build much greater levels till in a human that eats the beetal eating bird.

Eg. 3 DDT in food chain of coastal water of long island.

Genetic map or Linkage mapThese are maps based on the recombination frequency. It includes determination of linkage groups and determination of map distance. A linkage group does not show the physical distance between genes but rather their relative positions as determined by how gene loci are inherited together. The closer two genes are, the more often they will be inherited together. Linkage distance is measured in Centimorgan unit ( cM)

Chromosome map

These are used to identify the location of genes using special cytological techniques such as Chromosome Banding.

Bio-informatics

This is a new computer aided technology to store, retrieve, analyze or predict the composition or structure of bio-molecules. Classical bio-informatics mainly deals with the sequence analysis of DNA or Protein. The Human Genome Project is currently being completed with the help of Bio-informatics. New Bio-informatics includes Medical imaging or Image analysis, biologically inspired computation like Genetic Algorithms.

Pesticides

Organochlorides DDT, BHC, Aldrin, Endosulphan – These are lipophilic compounds accumulate In fat depots like liver.

Organophosphates Malathion, Parathion, Feritrothion- These affect nervous system.

Carbamates Carbaryl, Carbofuran - Inhibit Acetylcholine esterase.

Highly toxic pesticides DDT, BHC, Carbofuran, AldrinWell known pesticide Parathion

Insecticide for Malaria control Malathion

Furudan It is Carbofuran

Baygon It is Propoxus

Herbicides destroy the weeds by affecting the Photosystem II.

Pesticide Thread Mill More expensive and more poisonous pesticides used to obtain

target. Eg. Pesticides for Cotton in India.

Biopesticides

These are biological agents used to control pests. Devine and Colego first used Fungal spores in weed control.

Confusion technique of pest control uses Pheromones. It is used in IPM. Ecdysone,

JH etc are insect hormones used to control pests in IPM.

Pyrethrum is obtained from Chrysanthemum cinerariifolium is a natural plant insecticide. It is usedto make Mosquito coils.

Neem contains an Anti-feedant called Azadiraclitin.

Food crops

Barley, Cotton, Sorghum Ethiopia

Maize Mexico, Central America

Sunflower USA

Pineapple, Rubber Brazil

Tomato, Potato Aeruvian Andes

Orthodox seedsThese are seeds withstand low moisture and low temperature. Eg. Cereals, Legumes.

Recalcitrant seeds

These are seeds killed by drying and freezing. Eg. Jack fruit, Tea, Cocoa, Rubber, Palm.

ANIMAL KINGDOM-ONE WORD ANSWERS

1. Choanocytes or Collar cells of Sponges are concerned with intracellular digestion.2. Physalia (Portuguese man of War) is a polymorphic form with zooids like Gastro zooid

(feeding), Gonozooid (reproduction), Dactylozooid (protection) and Pneumatophore (floating).3. Alconium or “Dead man’s Finger” belongs to the class Anthozoa. Coral is formed of Calcium

carbonate.4. The single polyp in the coral colony is called as Corallite and the colony as Corallum. Some

of the common marine coelenterates are Pennatula (Sea Fan), Virgularia (Sea Whip), Gorgonia (Sea Fan) etc. Lakhsdeep, Rameswaram and Fiji are Coral islands.

5. Hirudo medicinalis is a leech used in Ayurvedic treatment to remove blood clots. There are 33 segments in the body of leech. Body cavity is filled with Botryoidal tissue. Hirunaria granulose is the ‘Cattle leech” and Haemodipsa is the “Land leech’

6. Ampullae of Lorenzini are the sense organs of fishes. Placoid scales of Shark resemble the tooth of mammals in structure.

7. Protopterus is the typical lung fish. Periophthalmus and Polypterus are lung fishes without internal nostrils. Anguilla is the larval form of Leptocehalus.

8. Rhacophorus is called as” Obstetric toad”. 9. Toxin secreted by the Parotid glands of Toad contains Bufotalin and Bufogin. Bidder’s organ of

toad is endocrine in function.10. Labyrinthodontia of Devonian period evolved into Amphibians. Crossopterygian fish Latimaria

is considered as the ancestor of Amphibians.11. Cotylosaurus is the “Stem Reptile” disappeared during Triassic period. High temperature, lack

of vegetation, increased aridity, and absence of mechanisms to protect eggs from mammals are the reasons for the extinction of Dinosaurs.

12. Heloderma is the only poisonous lizard. Sphenodon is a living fossil. 13. Mammals evolved from reptile like Dimetrodon in Triassic period.14. Mammals typically have 7 cervical vertebrae. But Sloth, Sea cow and Mantee have 6 to 9

cervical vertebrae.15. Prototheia is the only one group laying eggs (Echidna, Platypus). Corpus Callosum is absent in

Marsupials (Kangaroo, Opossum). 16. Bats belong to the order Chiroptera. Vampire bat is a blood sucking bat. 17. Tree shrew is considered as the remote ancestor of mammals. 18. Hognose Bat is the smallest mammal (formerly Pigmy water shrew was considered as the

smallest mammal). Dolphin is the intelligent aquatic mammal. 19. Echolocation is found in Bats, Whale and Dolphins. Giraffe is the tallest mammal and Cheetah

is the fastest mammal. Three toed Sloth is the slowest terrestrial mammal. 20. Enhydra lutris is the slowest aquatic mammal. 21. Gorilla is the largest Ape and Chimpanzee is the most intelligent Ape. 22. Gibbon is the only Ape found in India. 23. Closest primate relative of man is Gorilla. 24. Blue whale is the largest living mammal (30-50 tons body weight).

EVOLUTION – ONE WORD ANSWERS

25. Theory of Biogenesis was put forwarded by Louist Pasteur in 1862 to explain the origin of life. It states that life originate only from pre existing life.

26. Protobionts are aggregates of artificially produced pre-biotic molecules in experimental conditions. It shows the capacity to maintain internal environment but lacks the ability of division.

27. Coacervate is a mixture of proteins and polysaccharides surrounded by a film of water. Since a lipid bilayer is absent, it lacks the ability to divide.

28. Congogeny refers to the evolution of perception, expression and communication in the primitive organism (Eiobionts). Congogeny marked the diversification and evolution of photosynthesis.

29. Specimens with fake structures similar to plant parts are called as Pseudofossils. 30. Paleontology is the study of fossils. 31. Fossils are dead remains of plants and animals lived in the past ages. Fossils may be Unaltered

fossils (whole body buried in resin or ice), 32. Petrified fossils (replacement of body parts by minerals),33. Moulds (hardened mud surrounding the fossil) Casts (petrified fossil with moulds) and Prints

(foot prints of animals).34. Determination of the age of fossils is called Dating of fossils. Various methods used for dating

the fossils are Radioactive clock method, Radiocarbon method and Potassium Argon method. 35. The most accurate method of fossil dating is Electron-Spin Resonance method.36. Convergent evolution is the formation of similar structures in unrelated groups of organisms.

Wings of insects and birds evolved in the same line. Aquatic vertebrates also show characters evolved through convergent evolution.

37. Parallel evolution is the convergent evolution in closely related animals. For example the running adaptations in Horse and Deer.

38. Homologous organs have same structure but perform different functions. Examples are Pentadacyl limbs of vertebrates, Mouth parts of insects etc.

39. Molecular Homology is also found in animals. Example is the Blood Proteins of Man and Apes.

40. Analogous organs have different structures but perform same functions. Examples are Wing of insects, birds and bat, Flippers of whale and fins of fishes etc.

41. Vestigial organs are rudimentary non functional organs which were well developed and functional in the ancestors. About 90 Vestigial organs are found in man. Some of them are Nictitating membrane, Coccyx, Ear muscles, Vermiform appendix, Wisdom teeth, Hair on the body etc. Rudimentary pelvic girdle of Python, Wings of flightless birds, and Splint bone in the leg of horse are also vestigial organs.

42. Connecting link is an organism which possesses the characters of two different groups. Examples are Euglena, (plant and animal) Proterospongia (protozoa and porifera), Peripatus (annelida and arthropoda), Neoplina (annelida and mollusca), Lung fishes, Egg laying mammals, Archaeopteryx etc.

43. Atavism or Reversion is the reappearance of ancestral characters in present animals. Examples are ability to move ear pinna, hairy body, short tail, long canines etc.

VITAMINS-ONE WORD ANSWERS

Vitamins are regulators necessary for the normal metabolic activities. Deficiency of vitamins (Hypovitaminosis) causes Deficiency diseases. Vitamins are classified into Fat soluble (Vit. A, D, E and K) vitamins and Water soluble (Vit. B complex and Vit. C) Vitamins.

Fat-soluble vitamins

Vitamin A is called as Retinol, which is necessary for the synthesis of visual pigment Rhodopsin in the retina. It is richly present in red colored fruits and vegetables, milk etc. Deficiency of Vitamin A causes Nyctalopia (Night blindness) and Xerophthalmia (hardening of cornea).

Vitamin D is the Ergostertol synthesized in the skin from 7-dehydro cholesterol by the action of UV rays of sunlight. Vitamin D is present in butter, liver, eggs etc and is essential for the absorption of calcium and phosphorous from the intestine. Deficiency of vitamin D causes Rickets (malformed skeleton) in children and Osteomalacia (weakening of bones) in adults.

Vitamin E or Tocopherol is necessary for the reproductive functions. It is present in green vegetables, egg yolk etc.

Vitamin K or Phylloquinone is the Coagulation vitamin necessary for the synthesis of Prothrombin in the blood. It is present in leafy vegetables, egg, yolk etc. The colon bacteria also synthesize it.

Water soluble vitaminsVitamin B complex and Vitamin C are water-soluble and cannot be stored in the body. Therefore daily supply of these vitamins is required.

Vitamin B1 or Thiamine is present in rice bran, yeast etc. It forms a major component of coenzyme carboxylase. Deficiency of Thiamine leads to Beriberi (loss of appetite, weakness etc.)

Vitamin B2 is Riboflavin is necessary for the formation of FAD. It is present in green vegetables and its deficiency is Cheilosis (ulcers in the lips and tongue)

Vitamin B3 or Niacin is the active part of NAD and is available in yeast, milk, pulses etc. Pellagra (inflammation of skin, diarrhoea) is the deficiency disease.

Vitamin B5 (Panthothenic acid), Vitamin B6 (Pyridoxine) Vitamin H (Biotin) are also necessary for the cellular activities. Vitamin B12 or Cyanocobalamin is a Cobalt containing vitamin present in milk, fish etc. It is also synthesized in the intestine by the bacteria. Cobalamine is necessary for the synthesis of haemoglobin so the deficiency leads to Pernicious anemia.

Vitamin C or Ascorbic acid is richly available in Citrus fruits like lemon, orange etc. The richest source of Vit. C is Gooseberry. Vit.C is necessary for the immune system, skin, connective tissue etc. Deficiency of Vit. C leads to Scurvy.

Genetics Capsule

44. Codominance is the condition in which two dominant genes express together. Eg. AB blood group in man, Coat color in Cattle etc. Incomplete dominance is the partial expression of two dominant genes to produce a mixture of two characters. Eg. Sickle cell anemia, Pink flower in Mirabilis.

45. Polygenes (Multiple genes) are groups of genes controlling the same character. Eg. Skin color in man.

46. Multiple alleles are alternate forms of a gene expressing the same character. Eg. Blood groups in man, Coat color in Rabbit etc.

47. Epistatic gene suppresses the character of a gene (Hypostatic Gene). Eg. Coat color in Dogs, Coat color in Mice.

48. Pleotropism is the condition in which a gene produces multiple effects. Eg. Gene for sickle cell anemia, Eye color in Drosophila.

49. Lethal genes are harmful genes destroying the possessor. Eg. Thalassemia and Huntington’s chorea in man, leaf color in Snapdragon (Homozygous dominant). Some times homozygous recessive genes become lethal. Eg. Congenital Ichthyosis and Amaurotic idiocy in man.

50. Pedigree analysis is the method to trace back the ancestral characters by taking one or more characters from an individual. In the Pedigree tree, Squares represents males and Circles females. Shaded squares or circles indicate dominant traits and open squares or circles denote recessive traits.

51. Giant chromosomes are found in Dipteran insects. Polytene chromosome (Salivary gland of Drosophila) and Lamp brush chromosome (Amphibian Oocytes) are giant chromosomes. SAT chromosome possesses a swollen part (Satellite body) at the tip of the chromosome.

52. Somatic genes in the Y chromosomes are called Y linked or Holandric genes. Eg. Gene producing Hypertrychosis (hair in the ear pinna) in man.

53. Sex limited characters express only in one sex. It will not express in the other sex even if the gene is present. Eg. Feather pattern in Poultry, premature baldness in human males, milk production in cattles.

54. Sex influenced characters behave like Dominant in one sex and Recessive in the other sex. Phenotype will be different even though the genotype is same. Eg. Horn in Sheep, baldness in man, Hare lip etc.

55. Mutation is a sudden heritable change in organisms leading to variations. Mutation was observed by Hugo de Vris in Oenothera lamarkiana (Evening Prim rose).

56. Gene mutations (Point mutations) affect the genes.57. Cladogenic agents (X-ray, Gamma rays) are chromosome breaking agents. 58. Cri-du-chat syndrome is caused due to a deletion in the short arm of 5th chromosome. 59. Philadelphia chromosome is the small 22nd chromosome in man produced due to the

translocation between the chromosomes 9 and 22. It is seen in patients with Chronic myeloid leukemia (CML).

60. Colchicine is called as Mitotic Poison since it destroys spindle fibers and arrest mitosis. It is used to induce Polyploidy in plants. Triticale is the first man made Cereal produced by crossing Wheat and Rye and then inducing polyploidy.

61. Mutagens are agents causing mutations. Physical mutagens are X-ray, alpha, beta, gamma rays, UV rays etc. Chemical mutagens include Nitrous acid, Ethyl methane sulphonate (EMS), Acridine orange etc. Sharbati Sonora is a variety of Wheat produced by induced mutation.

62. Cistron is the smallest unit of DNA that transcribes a messenger RNA.63. Recon is the unit of recombination and Muton is the part of DNA that undergoes mutation.

64. B-DNA is the usual form of right handed DNA with 10 base pairs in one turn. A-DNA (11 base pairs), C-DNA (9 base pairs) and D-DNA (8 base pairs) are forms of DNA produced in experimental conditions.

65. Z-DNA is the left handed DNA discovered by Rich, Nordheim and Wang in 1984. It has 12 base pairs per turn.

66. Palindrome DNA has inverted repetition of base sequences.67. H-DNA contains inverted repetition of base sequences to form Triple helix DNA.68. Watson, Crick, Wilkins and Rosalind Franklin are associated with the Double Helical model of

DNA. There are 10 base pairs per turn in the DNA. The base pairs are separated by a distance of 3.4 Angstrom so the total length of the turn is 34 Angstroms.

69. Hydrogen bonds in the DNA stabilize the topology and antiparallel nature of DNA.70. Phospho diester bonds maintain the polarity (3’-5’ and 5’-3’) of the DNA strands.71. Helicase is the enzyme that separate DNA strands during replication. 72. Topisomerase (Relaxing enzyme) reduces tension in the DNA during unwinding. DNA

Polymerases I , II and III are DNA synthesizing enzymes. DNA polymerase III is the most active enzyme. Bacterial DNA Polymerases are Pol I and Pol II (DNA repair) and Pol III (Chromosome replication).

73. Ligase (Molecular glue) joins DNA segments after synthesis.74. Telomerase is the enzyme containing RNA and protein. It terminates DNA replication. 75. Reverse Transcriptase is the bacterial Polymerase that synthesise DNA from RNA.76. Primase (RNA polymerase) is used to synthesize Primer RNA during replication. 77. RNA Editing is the modification of the m-RNA before translation.78. Recombinant DNA technology involves manipulation of DNA which involves DNA cloning,

DNA profiling etc.79. R-DNA or Recombinant DNA contains a bacterial plasmid and a desired gene sequence of

another organism. 80. Restriction enzymes are “Molecular Scissors” that cut double stranded DNA at specific sites

producing ‘Staggered ends’. These enzymes are present in bacteria to destroy foreign DNA such as Viral DNA. The enzyme will not destroy the own DNA of bacteria because it is kept in the methylated form. Most widely used restriction enzymes are Eco R1, Bam 1, Hind III etc.

Molecular genetics

81. Cistron is the smallest unit of DNA that transcribes a messenger RNA. Recon is the unit of recombination and Muton is the part of DNA that undergoes mutation.

82. B-DNA is the usual form of right handed DNA with 10 base pairs in one turn. A-DNA (11 base pairs), C-DNA (9 base pairs) and D-DNA (8 base pairs) are forms of DNA produced in experimental conditions. Z-DNA is the left handed DNA discovered by Rich, Nordheim and Wang in 1984. It has 12 base pairs per turn. Palindrome DNA has inverted repetition of base sequences. H-DNA contains inverted repetition of base sequences to form Triple helix DNA.

83. Watson, Crick, Wilkins and Rosalind Franklin are associated with the Double Helical model of DNA. There are 10 base pairs per turn in the DNA. The base pairs are separated by a distance of 3.4 Angstrom so the total length of the turn is 34 Angstroms. Hydrogen bonds in the DNA

stabilize the topology and antiparallel nature of DNA. Phospho diester bonds maintain the polarity (3’-5’ and 5’-3’) of the DNA strands.

84. In Semi-conservative replication of DNA (proposed by Matthew, Mehelson and Stahl), two daughter DNA are formed each having a new and old strands. In Conservative replication, the parent helix remains intact. In Dispersive replication, all the four strands of two daughter DNA are mixture of parental and daughter DNA. Rolling circle model of DNA replication is proposed for the replication of Circular DNA of bacteria.

85. Helicase is the enzyme that separate DNA strands during replication. Topisomerase (Relaxing enzyme) reduces tension in the DNA during unwinding. DNA Polymerases I , II and III are DNA synthesizing enzymes. DNA polymerase III is the most active enzyme. Bacterial DNA Polymerases are Pol I and Pol II (DNA repair) and Pol III (Chromosome replication). Ligase (Molecular glue) joins DNA segments after synthesis. Telomerase is the enzyme containing RNA and protein. It terminates DNA replication. Reverse Transcriptase is the bacterial Polymerase that synthesise DNA from RNA. Primase (RNA polymerase) is used to synthesize Primer RNA during replication.

86. DNA replication occurs in the 5’-3’ direction because the DNA polymerase III can act only in this direction. “Leading strand” synthesis occurs in the 5’-3’direction. “Lagging strand” synthesis (Discontinuous synthesis) occurs as DNA segments called “Okasaki Fragments”. This is because the second strand of DNA has 3’-5 direction and Polymerase III can act only in the 5’-3’ direction.

87. Beadle and Tatum conducted experiments in Neurospora crassa (Pink bread mold) to show the relation ship between genes and enzymes. Wild type Neurospora (Prototroph) grow in Minimal medium containing few salts and minerals. Mutant forms (Auxotroph) grow only when amino acids like Ornithine, Citrulline and Arginine are added to the culture. Beadle and Tatum conducted tetrad analysis in Neurospora and proposed the “One Gene One Enzyme” hypothesis.

88. RNA Splicing involves the removal of Introns (non coding sequences) from the m-RNA. Then the Exons ( coding sequences) are joined together. RNA Editing is the modification of the m-RNA before translation. SnRNPs or Spurps are ribonucleoproteins binds to the m-RNA during RNA splicing. Spliceosomes are formed by the interaction of SnRNPs with other proteins. RNA capping is the process by which a guanine nucleotide (with methyl group) is added to the 5’ end of RNA after splicing. RNA cap determines the site of translation. PolyA tailing is the process by which a long tail of Adenine residue is added to the 3’ end of m-RNA during splicing. Ribozymes are RNA molecules act as enzymes. RNase P is a Ribozyme.

89. Recombinant DNA technology involves manipulation of DNA which involves DNA cloning, DNA profiling etc. R-DNA or Recombinant DNA contains a bacterial plasmid and a desired gene sequence of another organism. Restriction enzymes are “Molecular Scissors” that cut

double stranded DNA at specific sites producing ‘Staggered ends’. These enzymes are present in bacteria to destroy foreign DNA such as Viral DNA. The enzyme will not destroy the own DNA of bacteria because it is kept in the methylated form. Most widely used restriction enzymes are Eco R1, Bam 1, Hind III etc.

Classical Genetics

90. Germinal variations affect the reproductive cells. These are also called as Fluctuating variations, Sports or Saltations. Germinal variations are heritable. Genome denotes to the haploid set of chromosomes in a cell. Test cross is the back cross of F1 generation with the Recessive parent. Alleles are the alternate forms of a gene. Locus is the position of a gene.

91. Correns and Tschermak rediscovered Mendelism. Bateson and Punnet discovered Complementary action of genes. Davenport discovered Polygenic inheritance (Skin color) in man. Waldeyer coined the term Chromosome. Balbiani discovered Polytene chromosomes in Drosophila. Muller discovered mutagenic property of X- rays. Hershey and Chase conducted experiments in viral replication. Jacob and Monad proposed the Operon concept. Alec Jeffrey introduced DNA finger printing. Kari Mullis discovered Polymerase chain reaction (PCR).

92. Codominance is the condition in which two dominant genes express together. Eg. AB blood group in man, Coat color in Cattle etc. Incomplete dominance is the partial expression of two dominant genes to produce a mixture of two characters. Eg. Sickle cell anemia, Pink flower in Mirabilis. Polygenes (Multiple genes) are groups of genes controlling the same character. Eg. Skin color in man. Multiple alleles are alternate forms of a gene expressing the same character. Eg. Blood groups in man, Coat color in Rabbit etc. Epistatic gene suppresses the character of a gene (Hypostatic Gene). Eg. Coat color in Dogs, Coat color in Mice. Pleotropism is the condition in which a gene produces multiple effects. Eg. Gene for sickle cell anemia, Eye color in Drosophila. Lethal genes are harmful genes destroying the possessor. Eg. Thalassemia and Huntington’s chorea in man, leaf color in Snapdragon (Homozygous dominant). Some times homozygous recessive genes become lethal. Eg. Congenital Ichthyosis and Amaurotic idiocy in man.

93. Pedigree analysis is the method to trace back the ancestral characters by taking one or more characters from an individual. In the Pedigree tree, Squares represents males and Circles females. Shaded squares or circles indicate dominant traits and open squares or circles denote recessive traits.

94. Hofmeister first reported Chromosomes in 1849. Sutton and Bovery in 1902 independently proposed the Chromosome theory of Heredity. Chromosomes may be Metacentric (centromere in the middle), Submetacentric (centromere towards one end), Acrocentric (centromere near the end) and Telocentric (centromere at the tip). Giant chromosomes are found in Dipteran insects. Polytene chromosome (Salivary gland of Drosophila) and Lamp brush chromosome (Amphibian Oocytes) are giant chromosomes. SAT chromosome possesses a swollen part (Satellite body) at the tip of the chromosome.

95. Somatic genes in the Y chromosomes are called Y linked or Holandric genes. Eg. Gene producing Hypertrychosis (hair in the ear pinna) in man. Sex limited characters express only in one sex. It will not express in the other sex even if the gene is present. Eg. Feather pattern in Poultry, premature baldness in human males, milk production in cattles. Sex influenced characters behave like Dominant in one sex and Recessive in the other sex. Phenotype will be different even though the genotype is same. Eg. Horn in Sheep, baldness in man, Hare lip etc.

96. Mutation is a sudden heritable change in organisms leading to variations. Mutation was observed by Hugo de Vris in Oenothera lamarkiana (Evening Prim rose). Gene mutations (Point mutations) affect the genes. It may be Deletion (removal of bases), Addition or Insertion and Substitution (replacement of one base by another one). Substitution may be Transition (Purine-Purine or Pyrimidine-Pyrimidine change) or Tranversion (Purine-Pyrimidine change or vice versa). Transition is caused by Tautomerization (shifting of protons), Deamination (removal of amino group) or through base analogues (5-Bromo Uracil).

97. Gene mutations change the arrangement of genetic code in the DNA. So these are called Frame shift mutations. Mis-sense mutation changes the amino acid sequence in the protein. Non sense mutations results in termination codons. Silent mutations do not alter the amino acid sequence in the protein. Cladogenic agents (X-ray, Gamma rays) are chromosome breaking agents. Cri-du-chat syndrome is caused due to a deletion in the short arm of 5 th chromosome. Philadelphia chromosome is the small 22nd chromosome in man produced due to the translocation between the chromosomes 9 and 22. It is seen in patients with Chronic myeloid leukemia (CML).

98. Colchicine is called as Mitotic Poison since it destroys spindle fibers and arrest mitosis. It is used to induce Polyploidy in plants. Triticale is the first man made Cereal produced by crossing Wheat and Rye and then inducing polyploidy. Mutagens are agents causing mutations. Physical mutagens are X-ray, alpha, beta, gamma rays, UV rays etc. Chemical mutagens include Nitrous acid, Ethyl methane sulphonate (EMS), Acridine orange etc. Sharbati Sonora is a variety of Wheat produced by induced mutation