Genetic Fingerprinting

Question 1

What are variable number tandem repeats?

Answer 1

Repeating DNA base sequences that are non-coding.

Question 2

Why can VNRTs be used for genetic fingerprinting?

Answer 2

The number of VNRTS and the position in the genome differs between organisms.

Question 3

Describe the process of genetic fingerprinting.

Answer 3

1. Extract the DNA from the sample.
2. Amplify the DNA using the PCR system.
3. Use specific restriction endonucleases to cut the DNA into fragments. The enzymes must be cut at the start and end of the VNTR regions.
4. The DNA fragments will be different lengths depending on the number of VNTRs present. This means you can separate the DNA fragments using gel electrophoresis.
5. Treat the DNA to be single-stranded and expose the bases.
6. Add fluorescent DNA probes that are complementary to the VNTRs so they hybridise with the VNTRs.
7. View under UV light to visualise the bonds.
8. The more similar the pattern of the VNTRs in the DNA of the organisms tested the more closely related the organisms are.

Question 4

What are the uses of genetic fingerprinting in forensics?

Answer 4

The DNA in the blood found at a crime scene can be compared with the DNA of the suspects. If the genetic fingerprints match then the suspect was at the crime scene.

Question 5

What are the uses of genetic fingerprinting in medicine?

Answer 5

Some VNTR patterns are associated with certain genetic disorders and diseases and genetic fingerprinting can be used to identify them in a patient’s DNA.

Question 6

What are the uses of genetic fingerprinting in animal and plant breding?

Answer 6

Breeding between close relatives can increase the risk of genetic disorders in animals and plants. Genetic fingerprinting and the comparison of VNTRs can be used to see if two organisms are closely related.