8.5 - Genetic fingerprinting

Question 1

What does VNTR stand for?

Answer 1

variable number of tandem repeats

Question 2

Describe the steps in preparing a DNA sample for genetic fingerprinting

Answer 2

1. Extraction: DNA extracted from sample (can be amplified using PCR if small amount)
2. Digestion: DNA cut into millions of small fragments using restriction endonuclease
3. Separation: fragments separated using gel electrophoresis
4. Separation: gel immersed in alkali to separate double strands, transferred to nylon membrane, DNA fixed to nylon using UV light
5. Hybridisation: radioactive probes added and attach to comp base sequences, any not bound washed off and membrane dried
6. Development: radioactive probes on DNA fragments identified on X-ray film
   (or can be fluorescent)

Question 3

Describe how gel electrophoresis works

Answer 3

• DNA fragments injected into wells
• electric current applied along gel
• shorter fragment = travels further

Question 4

Name 2 uses of DNA profiling

Answer 4

• wildlife protection (detecting illegally traded animals)
• testing food for GM ingredients

Question 5

What is somatic gene therapy?

Answer 5

altering alleles of body cells

Question 6

What is germ line therapy?

Answer 6

altering sex cells