Introduction of Genetics
The Nature of Heredity
The study of heredity and the variation of inherited characteristics
HEREDITY: the passing of traits from parents to offspring
GENETICS
Genetic information is contained in a molecule of DNA
The modern DNA model has 3 parts:1. Composed of pentose sugar, a
phosphate group and one of four nitrogenous bases (Levene, 1920)
2. The proportion of nitrogenous bases are equal. (Chargaff, 1940)
3. DNA has a helix shape (Franklin, 1951)
DNA
The backbone of DNA is composed of phosphate group and pentose sugar.
The nitrogenous bases pair up:◦Thymine-Adenine◦Cytosine-Guanine
DNA
COMPLEMENTARY BASE PAIRING: pairing of the nitrogenous base of one strand of DNA with the nitrogenous base of another strand
You only need to know the nucleotide sequence for one strand
DNA
GENE: a segment of a DNA molecule that codes for a particular trait Found at a specific location on a chromosome
LOCUS: the location of a gene on a chromosome
CHROMOSOME: carries information for hundreds or thousands of different genes
GENETIC MATERIAL
REPRODUCTION
ASEXUAL SEXUAL
The production of offspring from a single parent
The genetic makeup of the offspring is identical to that of the parent
The production of offspring from the fusion of two sex cells
The genetic makeup of the offspring is different from that of either parent
There are 3 stages to the cell cycle:◦INTERPHSE◦MITOSIS◦CYTOKINESIS
CELL CYCLE
The period between cell divisions, where the cell grows, DNA replicates and the cell prepares for mitosis.
INTERPHASE
There are three parts to interphase:
◦G1 (First Gap) Phase: the cell is growing and preparing for replication
◦S (Synthesis) Phase: duplication of genetic material
◦G2 (Second Gap) Phase: cell begins final prep for cell division
INTERPHASE
The chromosomes in the nucleus form a mass of thread like structures called CHROMATIN
The replication of chromosomes results in a pair of SISTER CHROMATIDS
INTERPHASE
The process by which a cell divides the genetic material in its nucleus into two identical nuclei
Used for: Growth Reproduction Repair
MITOSIS
There are four phases of mitosis: PROPHASE METAPHASE ANAPHASE TELOPHASE
PHASES OF MITOSIS
Chromosomes shorten and thicken
Centrioles move to opposite poles of the cell
Spindle fibres form Nuclear membrane starts to dissolve
PROPHASE
Spindle fibres move to align the chromosomes
Chromosomes are lined up at the equator of the cell
METAPHASE
The chromosomes move to opposite poles of the cell
The chromosomes are pulled by their centromeres
ANAPHASE
Chromosomes are at opposite poles and start to unwind
Spindle fibres start to dissolve
Nuclear membranes reform
TELOPHASE
The process in which a cell divides its cytoplasm in to two new INDENTICAL daughter cells
The same number and type of chromosomes in each cell
CYTOKINESIS
The process of producing one individual that is genetically identical to another using a single cell or tissue
EXAMPLES: “Dolly” the sheep Genetically Modified Organisms Pharmaceutical products
CLONING
Cancer is occurs when cells divide uncontrollably
There are two kinds of cancer tumors: BENIGN: the cancer cells are not capable of spreading
MALIGNANT: the cancer cells are capable of spreading
CANCER