Recombinant DNA

1. Identify

• Identify locattion, base sequence

2. Isolation

• Isolate gene by restriction enzyme to cut DNA at restriction site to produce sticky ends and allow DNA molecules pair up and join together

3. insertion

4. insertion

5. Selection

6. Culture

7. Induce

8. Extract and purify

Polymerase chain reaction

Denaturation

• 95°C denatures DNA double helix separates into two single strands

Primer annealing

• 55°C primers with complementary bases anneal to the single strand DNA

Extension

• 72°C DNA polymerase joins complementary free nucleotides to primers accordingly to extend DNA molecule

DNA fingerprinting

Variable tandem repeats

• number of repeats varies geratly among individuals
• different lengths of repeats in different individuals
• repeats extracted using restriction enzyme
• gel electrophoresis: separates DNA fragments with differnt lenght
• denaturation of DNA fragments and transfer to membrane
• radioactive DNA probes
• DNA fingerprints on X ray film

STR
repeats shorter
amplified with PCR

Microorganisms

bacteriophages: infect bacteria

1. bacteriophaes attach to host cell and inject its DNA with gene of interest into the host cell
2. gene of interest integrates into bacterial chromosome

Plants

agrobacterium contains tumour inducing plasmid
plasmid carries gene of interest into plant cell and integrate with plant dna
select transformed cells on agar plate with nutrients and herbicide
Animals

Microinjection

fine pipette to inject

may damage ovum

Benefits of genetic engineering

• Science: way to study organisms at molecular level
• medical advancements
• solve food shortages and improve food quality
• environment

Cons

• antibiotic resistance
• allergies
• unknown effects on health
• genetic pollution

Cloning

Micropropagation

Embryo splitting

Pros of cloning

• preserve desirable characteristics of parent
• rapid reproduction
• endangered species
• biological factories to produce pharmaceutical products/ useful chemicals

Plants

• free of pathogens
• require less space

Animals

• animal clones for studying diseases and testing drugs
• provide stem cells for research and medical

Cons

Plants

• high cost of tissue culture
• lack of genetic variations, less adaptable to environmental changes

Animals

• low success rate and high cost
• age faster and have shorter lifespan