Genetic Engineering

• Genetic Engineering is the process of making changes in the DNA code of living organisms.

• Genetic Engineering and DNA Technology can be used to – Cure diseases– Treat genetic disorders– Improve food crops– Produce vaccines and

other useful drugs

Genetic Engineering Includes

• Selective Breeding & Crossbreeding

• Recombinant DNA

• Transgenic Organisms

• PCR

• DNA Fingerprinting

• Gel Electrophoresis

• Cloning

Selective Breeding

• Breed only those plants or animals with desirable traits

• People have been using selective breeding for 1000’s of years with farm crops and domesticated animals.

Hybridization (Crossbreeding)

• Producing new organisms by the mating individuals of different breeds, varieties, or species Male Donkey + Female Horse = Mule

Recombinant DNA

• rDNA has been artificially created

– DNA from two or more sources is recombined into a single molecule

• To create rDNA, scientists use restriction enzymes to cut DNA in precise locations

• Restriction enzymes create “sticky ends” that allow the DNA to bind to another piece of DNA with the same sticky ends

Recombinant Bacteria1. Remove a Plasmid

– A plasmid is a small circular piece of DNA found in bacteria

2. Cut the Bacterial DNA with restriction enzymes

3. Cut the desired gene from another organism’s DNA with restriction enzymes

4. Combine the cut pieces of DNA together and insert them into bacteria.

5. Reproduce the recombinant bacteria.

6. The foreign genes will be expressed in the bacteria.

Recombinant Bacteria

Benefits of Recombinant Bacteria

1. Bacteria can make human insulin or human growth hormone.

1. Bacteria can be engineered to “eat” oil spills.

Transgenic Organisms

• The genetic code is universal, therefore it is possible to make organisms that are transgenic

• Transgenic organisms contain genes from other species

• They are also called GMO’s – Genetically Modified Organisms

This tobacco plant glows in the dark because scientists gave it the gene that causes fireflies to glow

Transgenic Plants

• Disease-resistant and insect-resistant crops

• Hardier fruit

• 70-75% of food in supermarket is genetically modified.

Transgenic Animals

• Mice – used to study human immune system

• Chickens – more resistant to infections

• Cows – increase milk supply and leaner meat

• Goats, sheep and pigs – produce human proteins in their milk

Polymerase Chain ReactionPCR

• PCR is a fast and inexpensive technique used to amplify (copy) small amounts of DNA1. Heat the DNA so it “unzips”.2. Add the complementary nitrogenous bases.3. Allow DNA to cool so the complementary

strands can “zip” together.

DNA Fingerprinting

• A technique used by scientists to distinguish between individuals of the same species using only samples of their DNA

• Unless they are identical twins, individual organisms all have unique DNA.

• The chemical structure of the DNA may be the same (A, T, C & G), but the order of the base pairs is different

DNA Fingerprinting Process

• First, DNA must be obained from blood, bodily fluids, hair roots, skin, or elsewhere

• After the DNA is isolated, it is amplified using PCR• Then the DNA is treated with restriction enzymes

– Cut the DNA at specific sequences

• This results in different sized fragments• These fragments are separated, based on size,

using a process called Gel Electrophoresis

Gel Electrophoresis

• DNA fragments are separated as they migrate through an agarose gel matrix

• This size-based separation occurs when an electric current is applied to the gel

Gel Electrophoresis

• DNA is a negatively charged molecule, so it will move toward the positive end of the chamber

• The smaller fragments will move faster and farther than the larger fragments

Gel Electrophoresis Steps1. “Cut” DNA sample with restriction enzymes.

2. Run the DNA fragments through a gel.

3. Bands will form in the gel.

4. Everyone’s DNA bands are unique and can be used to identify a person.

DNA Fingerprinting

• DNA fingerprinting can show which individuals are the parents of specific children

– A child’s DNA fragments must be inherited from his or her biological parents

DNA Fingerprinting

• DNA fingerprinting can also be used to help solve crimes

Cloning

• Cloning is the creation of an organism that is an exact genetic copy of another– Their DNA is identical

• Produced by asexual reproduction– Mitosis

Cloning

• Dolly the sheep was the first animal to be successfully cloned in 1997

• There were 277 failures before this nuclear transfer technique succeeded