8.8 Genetic fingerprinting

Question 1

What are VNTRs?

Answer 1

• Repeating sequences of nucleotides
• Found in non-coding DNA at many sites throughout an organims genome
• Differ between individuals

Question 2

How can genetic fingerprinting be used to analyse DNA fragments?

Answer 2

• Extract DNA and amplify by PCR
• Cut DNA at specific base sequences using restriction enzymes
• Separate DNA fragments using gel electrophoresis
• Transfer to nylon membrane and treat to form single strands with exposed bases
• Add labelled DNA probes with hybridise with complementary VNTRs
• Expose to UV light if fluorescent label used or use autoradiography if radioactive label used

Question 3

How can genetic fingerprinting be used to determine genetic relationships?

Answer 3

• More closely related organisms have more similar VNTRs
• Father should share around 50% of VNTRs with child