Genetic Engineering

Genetic Engineering

• Genetic Engineering:

The development and application procedures, and technologies that allow you to directly manipulate an organisms DNA

• We can manipulate DNA and genes

to alter organisms or make them

produce a product we need.

Genetic Engineering (g.e)

1. It is the process of inserting genes of interest into

specific organisms for either a medical or scientific

benefit.

2. Gene therapy is the process of inserting a missing

gene into an organism.

3. Bacteria are often used as the factories to produce a

protein from a cloned gene. This has led to the

production of human insulin,GH & erythropoietin..etc.

4. The gene must be cloned into an expression vector,

usually a plasmid with special features that allows it

to be transcribed & translated in a host cell.

Genetic Engineering in

Agriculture 1. Disease resistance e.g. corn & cotton

2. Nitrogen fixation

3. Frost-free plants e.g. strawberries & potatoes

4. Tomatoes with a long shelf life deactivating the

gene in tomato which produce ethylene.

5. Increased milk production giving cows bovine

somatotropin (BST) “growth hormone”….

6. Good predator attraction strawberry gene on

mustard plants produces a chemical attractant for

predator mites that eat the herbivorous spider

mites.

Fig. 13-18, p.349

Transgenic tomato plant : Recombinant DNA methods have produced plants

that resist defoliation by caterpillars, with longer shelf life.

• Genetic engineering: Changing the DNA in

living organisms to create something new.

• This organisms are called Genetically

Modified Organism (GMO)

• Example:

• Bacteria that produce human insulin

• Genetically Modified organism are called

transgenic organism; since genes are

transferred from one organism to another.

Some genetic engineering techniques are

as follows:

1. Artificial selection

2. Cloning

3. Gene splicing

4. Gel electrophoresis: analyzing DNA

1. Artificial selection: breeders choose which

organism to mate to produce offspring with

desired traits.

• They cannot control what genes are passed.

• When they get offspring with the desired traits,

maintain them.

Three types of artificial selection:

A. Selective breeding

B. Hybridization

C. Inbreeding

A. Selective breeding: when animals with

desired characteristics are mated to

produce offspring with those desired traits.

• Passing of important genes to next

generation.

• Example: Champion race horses, cows

with tender meat, large juicy oranges on a

tree.

• Examples of selective breeding:

• Angus cows are bred to

increase muscle mass so that we get more meat,

• Egg-Laying Hen-produces more eggs than the average hen

• Selective breeding occurs when you choose the

best male and female to breed.

• This allows you to fine tune and control the

traits

• The offspring or babies will then have the best

traits.

• Then you continue to breed those organism

with the best traits, those traits will be

maintained.

Selective Breeding

• Selective Breeding: allowing only those organisms with desired characteristics to reproduce.

– How could you use selective breeding to develop dogs with more intelligence?

– Selective breeding takes advantage of natural genetic variation (the trait must already exist in the population)

2 Methods of selective breeding

1. Hybridization: crossing dissimilar individuals together to get the best of both organisms

Ex: Killer Bees – While attempting to create a bee that produces more honey in tropical climates scientist bred a European honey bee with a African honey bee.

2. Inbreeding: the continued breeding of individuals with similar characteristic Ex: Purebred Dog Breeds – dog breeds are created by

breeding individuals with similar characteristics to ensure that the combination of traits will be passed on to the next generation.

Selective Breeding

• B. Hybridizations: two individuals with unlike

characteristics are crossed to produce the best in both

organisms.

• Example: Luther Burbank created a disease resistant

potato called the Burbank potato.

• He crossed a disease resistant plant with one that had

a large food producing capacity.

• Result: disease resistant plant that makes a lot of

potatoes.

Other Examples of hybridization:

1. Liger: lion and tiger mix

2. Grape + apple= grapple. The fruit

tastes like grapes and looks like apple.

C. Inbreeding breeding of organism that

genetically similar to maintain desired traits.

• Dogs breeds are kept pure this way.

• Its how a Doberman remains a Doberman.

• It keeps each breed unique from others.

• Risk: since both have the same genes, the

chance that a baby will get a recessive

genetic disorder is high.

• Risks: blindness, joint deformities.

Selective Breeding • In order for selective

breeding to work, you need a wide variation of genetic traits.

– Explain you cannot use selective breeding to create a monkey that glows in the dark?

• How do new traits get introduced into a population?

– Induce mutations to develop new traits in a population

(Mutations are the ultimate source of genetic traits)

Limitations of selective breeding and mutations:

–Selective breeding requires traits already exists in a population – we can not make new traits.

–Mutations are unpredictable and will not create the exact traits that we want. (most mutations are harmful to the organism)

Selective Breeding

• Variation: difference between individuals of a species.

• The differences are in the genes but we see the physical differences.

• For example: Some humans have blond hair and some have brown. This is a variation among humans.

• Inbreeding decreases variations.

2. Cloning: creating an organism that is an

exact genetic copy of another.

• There are human clones in our school.

• Identical twins are naturally created clones.

• Eggs are haploid

• Haploid: half the

chromosomes, 23 in

humans

• Body cells are diploid:

• Diploid: two sets of

chromosomes, one from

mother and one set from

father 46 in humans.

• This picture represents gene splicing.

• However, DNA is much smaller.

• Its done with high tech lab equipment since

DNA, is too small to hold or see without a

microscope.

The red piece the woman

is holding is an insulin

gene from a human

being. It is being

combined with DNA from

a bacteria.

Creates recombinant

DNA, something that has

never existed before.

Benefits:

• Insulin is cheaper

• There are no side

effects because it

is human insulin.

• We once used pig

insulin but there

are side effects

and it is more

expensive.

How is gene splicing done?

1. A restriction enzyme cuts the insulin gene out of the human DNA.

2. A plasmid is removed from a bacteria and cut with a restriction enzyme

3. The human gene is place into the bacteria

plasmid

4. The plasmid is placed back into the bacteria.

• The cell now has directions (DNA) to make

insulin.

• That's exactly what it does.

• Its human insulin, bacteria do not make insulin

on their own.

Plasmid with

insulin gene

• This is called transformation: when a gene

from one organism is transferred to different

organism.

• The organisms that have DNA transferred to

them are called transgenic organisms.

• trans: means different,

• genic: refers to genes

• Genetic engineering has given rise to a new

technological field called biotechnology

(technology of life).

1. Transgenic (GMO) animals: genes inserted

into animals so they produce what humans

need.

• Why?: A way to improve the food supply:

A. Transgenic cows: gene inserted to

increase milk production.

B. Spider goat: gene from spider inserted

into goat.

• Goats makes silk of the spider web in their

milk.

• Flexible, stronger than steel. Used in

bullet proof jackets.

C. Glow-in-the-dark

cats

• Scientist used a

virus to insert DNA

from jellyfish

• The gene made the

cat produce a

fluorescent protein

in its fur.

2. Transgenic bacteria: gene inserted into

bacteria so they produce things humans

need.

• For example: insulin and clotting factors in

blood are now made by bacteria.

3. Transgenic plants: plants are given genes

so they meet human needs.

A. Transgenic corn: given a gene so corn

produces a natural pesticide.

Now they don’t have to be sprayed with

cancer causing pesticides.

• 25% of all corn is like this.

B. Venomous cabbage

• Gene from a scorpion tails

inserted into cabbage.

• Cabbage now produces

that chemical.

• Why? Limit pesticide use

while still preventing

insects from damaging

crops.

• Corporations state the

toxin is modified so it isn’t

harmful to humans.

C. Banana vaccines

• Virus is injected into a banana, the virus DNA becomes part of the plant.

• As the plant grows, it produces the virus proteins — but not the disease part of the virus.

• When people eat a bite, their immune systems creates antibodies to fight the disease — just like a traditional vaccine

• Vaccines for hepatitis and cholera

Medicinal eggs

• British scientists have created a breed

of genetically modified hens that

produce cancer-fighting medicines in

their eggs. The animals have had

human genes added to their DNA so

that human proteins are secreted into

the whites of their eggs, along with

complex medicinal proteins similar to

drugs used to treat skin cancer and

other diseases.

• What exactly do these disease-fighting

eggscontain? The hens lay eggs that

have miR24, a molecule with potential

for treating malignant melanoma and

arthritis, and human interferon b-1a,

an antiviral drug that resembles

modern treatments for multiple

sclerosis.

Fast-growing salmon

• genetically modified

salmon grows twice

as fast as the

conventional variety

— the photo shows

two same-age

salmon with the

genetically altered

one in the rear.

• A virus is often used to deliver DNA.

• In the movie “I Am Legend,” A healthy gene was inserted into a virus.

• The virus invaded the cancer cells and inserts the healthy gene to cure cancer.

• Worked at first but the virus mutated and became deadly.

• This is being attempted in real life.

• Gene therapy: when disease causing

genes are cut out and good gene are

inserted.

• Restriction enzymes are used to cut out

bad genes.

• Viruses are used to insert good genes.

• Not approved for human use yet.

• Some possible side effects.

4. Gel electrophoresis: a

technique used to compare

DNA from two or more

organisms.

Why compare DNA:

1. Find your baby’s daddy

2. Who committed a crime.

3. How closely species are

related.

How is electrophoresis done?

A. The DNA is cut into fragments with a restriction enzyme.

B. The cut DNA is then put into the wells of a machine filled with gel.

• The gel is spongy and the DNA squeezes through the pores.

C. The machine is plugged in and the

fragments get separated based on their size.

• The smaller fragments move further than the

large.

• Electrophoresis

results

Separation of DNA based on

size of fragments.

Final result of electrophoresis

• Electricity provides the energy

• Why does DNA move?

• DNA has a negative charge.

• When the machine is plugged it, its moves towards

the positive pole created by the electricity

electrophoresis

Your DNA is so unique its considered to be a

DNA fingerprint.

Gel electrophoresis will separate your DNA

differently from anyone else.

Nova: who done it http://www.pbs.org/wgbh/nova/sheppard/analyze.html

http://www.teachersdomain.org/asset/tdc02_i

nt_creatednafp2/