topic 4.4: genetic engineering and biotechnology
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Topic 4.4: Genetic engineering and biotechnology. Assessment Statements. 4.4.1 Outline the use of polymerase chain reactions (PCR) to copy and amplify minute quantities of DNA - PowerPoint PPT PresentationTRANSCRIPT
TOPIC 4.4: GENETIC
ENGINEERING AND
BIOTECHNOLOGY
ASSESSMENT STATEMENTS 4.4.1 Outline the use of polymerase chain reactions (PCR) to copy and amplify
minute quantities of DNA 4.4.2 State that, in gel electrophoresis, fragments of DNA move in an electric field
and are separated according to their size 4.4.3 State that gel electrophoresis of DNA is used in DNA profiling 4.4.4 Describe the application of DNA profiling to determine paternity and also in
forensic investigations 4.4.5 Analyze DNA profiles to draw conclusions about paternity or forensic
investigations 4.4.6 Outline three outcomes of the sequencing of the complete human genome 4.4.7 State that, when genes are transferred between species, the amino acid
sequence of polypeptides translated from them is unchanged because the genetic code is universal
4.4.8 Outline a basic technique used for gene transfer involving plasmids, a hose cell (bacterium, yeast, or other cell), restriction enzymes (endonucleases) and DNA ligase
4.4.9 State two examples of the current uses of genetically modified crops or animals
4.4.10 Discuss the potential benefits and possible harmful effects of one example of genetic modification
4.4.11 Define clone 4.4.12 Outline a technique for cloning using differentiated animal cells 4.4.13 Discuss the ethical issues of therapeutic cloning in humans
EXPLORING DNA DNA is at the very core of what gives
animals and plants their uniqueness New discoveries in genetic techniques
include:Copying DNA (PCR)DNA revealing owner’s id (DNA Profiling)Mapping DNA (Human Genome Project)Cutting and pasting genes (gene transfer)Cloning cells and animals
EXPLORING DNA These new techniques offer new hope
for:Treatment and vaccinesCreating new plantsFree or convicting people
POLYMERASE CHAIN REACTION PCR is a laboratory technique which
takes very small quantity of DNA and copies all the nucleic acids in it to make millions of copies of the DNASolves a very simple problem-not enough
DNA to analyzehttp://
www.dnalc.org/resources/animations/pcr.html
http://learn.genetics.utah.edu/content/labs/pcr/
GEL ELECTROPHORESIS This laboratory technique is
used to separate fragments of DNA in an effort to identify its origin Enzymes are used to chop up
the long filament of DNA into varying sized fragments
DNA fragments are placed into small wells (holes) in the gel which are aligned along one end
The gel is exposed to an electric current (positive on one side and negative on the other)
GEL ELECTROPHORESIS The effect is that the
biggest , heaviest, and least charged particles do not move easily through the gel
Smallest, least massive and most charged particles pass through the gel to the other side with little difficulty
In the endThe fragments leave a banded pattern of DNA
http://learn.genetics.utah.edu/content/labs/gel/
https://www.msu.edu/~russellr/portfolio/electrophoresis/electrophoresis.html
DNA PROFILING The process of matching an unknown
sample of DNA with a known sample to see if they correspond is call DNA profilingAKA DNA fingerprinting
If, after separation by gel electrophoresis, the:Pattern of bands formed by two samples
of DNA fragments are identical, it means that both most certainly came from the same individual
Patterns are similar, it means that the two individuals are most probably related
DNA PROFILING Applications of DNA profiling
Paternity suitsMatch DNA to suspectDetermine how closely related species are
to each otherDetermine evolution
HOW DNA PROFILES ARE ANALYZED Look at page 102
HUMAN GENOME PROJECT 1990-started an international
cooperative venture-Human Genome ProjectGoal: sequence the complete human
genome 2003-annouced they succeeded the
projectScientist are working on deciphering which
sequences represent genes and which do what
With genome libraries of genetic diseases, doctors can find out exactly where to look if they think one of their patients might possess a disease-carrying allele
HUMAN GENOME PROJECT Other Advantages:
Produce new medications, Steps: Find beneficial molecules which are produced
naturally in healthy people Find out which gene controls the synthesis of a
desirable molecule Copy that gene and use it as instructions to
synthesize the molecule in a laboratory Distribute the beneficial molecule as a new treatment
By comparing the genetic makeup of populations around the world, countless details could be revealed about ancestries and how humans migrated and mixed their genes with other populations over time
GENE TRANSFER The technique of taking a gene out of
one organism and placing it in another organism is a genetic engineering procedure called gene transfer It is possible to transfer any species genes
into another species makeup Example: proteins used by fish to resist the icy
temperature of arctic waters are now produced by the modified tomatoes to make them more resistant to cold
Example: corn, genetically engineered to produce toxins that kill the bugs which attack it (take protein from Bacillus thuringiensis)
CUTTING AND PASTING DNA The scissors used for cutting base
sequences are called restriction enzymesRestriction enzymes called endonucleases
find and recognize a specific sequence of base pairs along the DNA molecule (4 or 6 sets of base pairs)
The endonucleases cut the DNA at the specific points If both the beginning and the end of a gene are
cut, the gene is released and can be removed from the donor organisms
CUTTING AND PASTING DNA For pasting genes, the enzyme used is
called DNA Ligase It recognizes the parts of the base
sequences that are supposed to be clicked together, called sticky ends, and attach them
http://www.dnalc.org/resources/animations/restriction.html
COPYING DNA (DNA CLONING) This is more complex because a host
cell is needed in addition to the cutting and pasting enzymes. (most common- Escherichia coli)Some DNA is found in structures called
plasmids Plasmids are small circles of extra copies of DNA
floating around inside the cell’s cytoplasmTo copy a gene, it must be glued into a plasmid
Plasmid is removed from the host cell and cut open using a restriction endonucleases
COPYING DNA (DNA CLONING) To copy a gene, it must be
glued into a plasmid Plasmid is removed from the
host cell and cut open using a restriction endonucleases
The gene to be copied is placed inside the open plasmidProcess called gene splicing
The plasmid is now called a recombinant plasmid and can be used as a vector, a tool for introducing a new gene into an organism’s genetic makeup
COPYING DNA (DNA CLONING) In the final step needed for copying (or
cloning) the gene.The vector is placed inside the host
bacterium and he bacterium is given its ideal conditions to grow and proliferate. Done by putting the bacterium into a vat of
nutritious liquid kept at a warm temperature Example: Used to make insulin
GENETICALLY MODIFIED ORGANISMS (GMO) Is one that has had an artificial genetic
change using the techniques of genetic engineeringOne of the main reasons is to be more
competitive in food production
GENETICALLY MODIFIED ORGANISMS (GMO) Transgenic plants
Simplest kind of GM food is one in which an undesirable gene is removed
In some cases, another more desirable gene is put in its place.
First Example of GM Food1994-Flavr Savr tomato-genetically
modified to delay the ripening and rotting process
Another tomato-able to grow in high salinity soil
Rice-engineered to produce beta carotene
GENETICALLY MODIFIED ORGANISMS (GMO) Transgenic animals
Haemophilia-Factor IX Using transgenic sheep
IS GENETIC ENGINEERING A GOOD OR A BAD THING Genetic engineering raising many social
or ethical questions
IS GENETIC ENGINEERING A GOOD OR A BAD THING Benefits, promises, and hopes for the future
GM crops will help farmers by improving food production GM crops which produce their own pest-control
substances will be beneficial to the environment because fewer chemical pesticides will be needed
Using GMOs to produce rare proteins for medicines or vaccines could be, in a long run, less costly and produce less pollution than synthesizing such proteins in laboratories
Farmers can be more in control of what crops or livestock they produce (selective breeding)
The multinational companies who make GM plants claim that they will enable farmers in developing nations to help reduce hunger by using pest-resistant crops or GM plants which require less water
IS GENETIC ENGINEERING A GOOD OR A BAD THING No one knows the long-term effects of GMO’s in the
wild There is a danger that the genes could cross species Bt-crops which produces toxins to kill insects could
be harmful to humans. The risks of allergies (may be allergic to one but not
another) Critics are worried that large portions of the human
food supply will be the property of a small number of corporations
High tech solutions are not necessarily better than simpler solutions
A proliferation of genetically modified organisms may lead to a decrease in biodiversity
IS GENETIC ENGINEERING A GOOD OR A BAD THING Clones and cloning
The definition of a clone is a group of genetically identical organisms or a group of cells artificially derived form a single parent In either case, the resulting cells or organisms
were made using laboratory techniques In farming, clones have been made for decades
for regenerating plant material or by allowing an in-vitro fertilized egg or divide to make copies of itself
CLONING USING A DIFFERENTIATED ANIMAL CELL 1996, a sheep by name of Dolly was
bornFirst clone whose genetic material did not
originate from an egg cellThis type of cloning is called reproductive
cloning because it makes an entire individual
CLONING USING A DIFFERENTIATED ANIMAL CELL Steps to create Dolly
First the original donor sheep to be cloned, a somatic cell from the udder was collected and cultured. The nucleus was removed from a cultured cell
An unfertilized egg was collected from another sheep and its nucleus was removed
Using a zap of electrical current, the egg cell and the nucleus form the cultured somatic cell were fused together
The new cell developed in vitro in a similar way to a zygote and started to form an embryo
The embryo was placed in a womb of a surrogate mother sheep
Dolly was born, and was presented to the world as a clone of the original donor sheep
CLONING USING A DIFFERENTIATED ANIMAL CELL Cloning using undifferentiated cells
Therapeutic cloning-simply to make copies of cells Aim is to develop cells which have not yet gone
through the process of differentiationSince the first technique in this area
involved using embryos, the cells are referred to as embryonic stem cells (stem cell research)
ETHICAL ISSUES SURROUNDING THERAPEUTIC CLONING Since therapeutic cloning starts with the
production of human embryos, it raises fundamental issues of right and wrong Is it ethically acceptable to generate a new
human embryo for the sole purpose of medical research
ETHICAL ISSUES SURROUNDING THERAPEUTIC CLONING Major breakthroughs (current research):
Growing skin to repair a serious burnGrowing new heart muscle to repair an
ailing heartGrowing new kidney tissue to rebuild a
failing kidney
Most researchers and medical professionals are against the idea of reproductive cloning in humans