Topic 6.8: Biotechnology

Restriction Enzymes

• Produced by bacteria to protect themselves from invading viral DNA

• Act like scissors, cutting double stranded DNA at specific sequences

• Creates sticky ends or blunt ends

Restriction Enzyme Endoculeases

Enzymes recognize specific 4-8 bp sequences

• Some enzymes cut in a staggered fashion - “sticky ends”

• Some enzymes cut in a direct fashion - “blunt”

Origins of Restriction Enzymes

Discovered in bacteria, restrict the growth of bateriophage by cutting the viral DNA and rendering them harmless

Gel Electrophoresis

• Technique used to separate DNA fragments according to their size

• DNA fragments are negatively charged so they move towards the positive electrode

Polymerase Chain Reaction

Method used to make several copies of a specific DNA segment.

• Segments of DNA are amplified, creating large samples to analyze DNA when small samples are initially available

Bacterial Transformation

• Process of horizontal gene transfer where some bacteria take up foreign genetic material (naked DNA) from environment

• Introduces DNA to bacterial cells

• Only happens at specific times

• Can be incorporated into bacterial chromosome or in the cytosol (plasmid)

• Used to make medicine, modify food, or amplify DNA

Tag DNA Polymerase

Not denatured at 72 degrees C and still functional

Survive because of specialized enzymes that survive high temperatures.

Plasmids

• Small, circular DNA molecules, vehicle for transferring recombinant genes to a new host

• Serve as a vector

• Replicate independently of the chromosome