CGE: Genetic Fingerprinting

Question 1

Variable Number Tandem Repeats

Answer 1

Base sequences that don’t code for proteins and repeat to next to each other over and over.

Question 2

Genetic fingerprinting

Answer 2

Comparing the number of times a VNTR sequence is repeated at different places in an individual’s genomes.

Question 3

Why is the probability of two individuals having the same genetic fingerprint low?

Answer 3

The chance of two individuals have the same number of VNTRs at each place they’re found in the DNA is very low.

Question 4

Describe how a genetic fingerprint is produced:

Answer 4

• Sample of DNA is obtained.
• PCR is used to make many copies of DNA areas that contain the VNTRs - primers are used to amplify the whole repeat as they bind to either side.
• DNA fragment left corresponds to the number of repeats a person has at each specific position.
• Fluorescent tag is added to all DNA fragments.
• DNA fragments under electrophoresis.
• Viewed under bands of UV light - genetic fingerprint.
• Two genetic fingerprints are compared.

Question 5

Describe the process of electrophoresis:

Answer 5

1. DNA mixture is placed into a well in a slab of gel and covered in a buffer solution that conducts electricity.
2. Electrical current is passed through the gel.
3. DNA fragments are negatively charged and so move towards the positive electrode at farends of gel.
4. Small DNA fragments move faster and travel further, so DNA fragments separate according to size.

Question 6

What are the two main uses of genetic fingerprinting?

Answer 6

• Determining genetic relationships - VNTR base sequences are inherited.
• Determining genetic variability within a population - greater the number of bands that don’t match, the more gentically varied the population.

Question 7

Describe how PCR could be used in forensic science:

Question 8

How can genetic fingerprints be used in medical diagnosis?

Answer 8

• Used to diagnose genetic disorders and cancer.
• Useful when the specific mutation isn’t know or there are several mutations that could have caused the disorder, as it identifies a broder, altered genetic pattern.

Question 9

How can genetic fingerprinting be used in animal and plant breeding?

Answer 9

• Used to prevent inbreeding + identify how closely related individuals are.
• Reduces the risk of genetic disorders leading to health, productivity and reproductive problems.