28. Genetic Disease Testing

Question 1

Why is PCR used to test diseases within people/animals gene? (2 points)

Answer 1

It distinguishes alleles based on length

PCR is very sensitive to amplify the repeat region of interest

Question 2

What will the gel look like after PCR with a diseased gene vs a normal gene

Answer 2

The diseased gene will have a larger band that runs along the gel.
In diploid organisms there will be two bands (one from maternal, one from paternal)
Diseased genes will be further apart as the restriction enzyme wouldnt have cut the DNA at the area of interest
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Question 3

Why is it important to know if the disease is heterozygous recessive/dominant or homozygous recessive/dominant? 2 points

Answer 3

Animals and humans are diploid so its necessary to know if the carrier is recessive or dominant (hasn’t or has) the disease passing onto offspring.
The longer the disease is running along the gel, the more prominent the disease is.
Punnet square is necessary to see what the probability is of passing on genes
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Question 4

What is the role of restriction enzymes in PCR?

Answer 4

Restriction enzymes find a particular sequence for where the DNA sequence can be cut. They are used to find mutations in the chromosomes to compare normal vs mutated genes.

Question 5

How do restriction enzymes work for genetic disease testing?

Answer 5

The restriction enzymes can cut the DNA on the normal DNA as the specific restriction enzyme cuts the DNA at the particular base sequence (eg ATG) but the mutated base sequence wont be cut (eg ACG) as the particular enzyme dosent cut that sequence
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Question 6

What does RFLP-PCR stand for?

Answer 6

Restriction fragment length polymorphism polymerase chain reaction

Question 7

What is RFLP-PCR?

Answer 7

When restriction enzymes that code for a normal gene (eg ATG) are used to cut the DNA, then the same enzyme is used to cut the mutated gene (eg ACG) in the area of interest (SNP area)
The restriction enzyme won’t cut the mutated gene as it dosent have the base pair matching with the normal gene.
The gel electrophoresis will make a long, thick strand on the gel, indicating a mutation
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Question 8

What is the three step procedure for genetic testing?

Answer 8

1. PCR amplification
2. Restriction enzymes cut the DNA
3. Run DNA on the gel