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