3.4.8 Genetic fingerprinting

Question 1

What is genetic fingerprinting?

Answer 1

• Analysis of DNA (entire genome)

- Creates a pattern of DNA that is unique to individuals (different sized DNA fragments)

Question 2

4 uses of genetic fingerprinting

Answer 2

• Determining genetic relationships e.g. paternity testing
• Determining genetic variability in a population (the more similar the banding patterns, the less variation in population)
• Prevents in-breeding in animals and plants after determining genetic variability in population
• Crime scene investigations

Question 3

What does VNTR stand for and what are they?

Answer 3

Variable number Tandem Repeats

• non coding DNA base sequences which repeat next to each other
• number of times the sequences repeat vary form person to person

Question 4

Why do VNTRs mean there is a wide range of variations between individuals?

Answer 4

VNTRs accumulate mutations without it affecting function of a gene, no number of repeats is selected for or against because they have no evolutionary impact (spliced out)

probability of two individuals having the same VNTRs is very low (pretty much impossible)

Question 5

6 stages of genetic fingerprinting

Answer 5

• Obtaining a sample
• Amplify the DNA
• Digest the DNA
• Separate the fragments
• Hybridsation / identification
• Analysis

Question 6

Isolation of VNTRs

Answer 6

• DNA sample obtained
• Amplified using PCR
• DNA cut into the wanted VNTR sequences using multiple restriction enzymes - this isolates only the VNTRs from DNA

Question 7

Identifying the VNTRs

Answer 7

• H bonds in DNA are broken (heating/ adding alkaline solution)
• DNA probes (with a label) specific to the VNTRs are added and they hybridise to the VNTRs by complementary base pairing

Question 8

How are fragments separated?

Answer 8

• separated by gel electrophoresis

- different length fragments travel different distances