genetic fingerprinting

Question 1

give 3 characteristics of a variable number tandem repeat (VNTR)

Answer 1

• non coding
• inherited from parents
• unique in all except twins

Question 2

give the name for VNTR’s

Answer 2

variable number tandem repeat

Question 3

what are the 5 stages of genetic fingerprinting

Answer 3

1. extraction
2. digestion
3. separation
4. hybridisation
5. development

Question 4

what happens during the extraction stage in DNA fingerprinting

Answer 4

extract DNA from the sample

Question 5

what happens during the digestion stage in DNA fingerprinting

Answer 5

restriction endonucleases cuts DNA into fragments

Question 6

what happens during the separation stage during genetic fingerprinting

Answer 6

separate fragments using gel electrophoresis and transfer from gel to nylon membrane

Question 7

what happens during the hybridisation stage in DNA fingerprinting

Answer 7

add DNA probes to label DNA fragments

Question 8

what do you do after the hybridisation stage (adding the probes)

Answer 8

wash the DNA

Question 9

what happens during the development stage in DNA fingerprinting

Answer 9

nylon membrane with DNA fragments place on x ray films, development of the film reveals dark bands where the probes have attached

Question 10

explain the technique of gel electrophoresis

Answer 10

• Used to separate DNA fragments in size order
• DNA fragments on agar gel with voltage across it
• negatively charged DNA moves towards the anode (positive)
• larger fragments the slower the movement
• therefore less distance travelled in a fixed time
• separate strands using alkali
• apply nylon membrane
• fragments labelled with DNA probe
• determine final position on gel by applying x ray film over the gel
• radioactivity from the DNA exposes the film and maps the fragments