Question 1

Which of the following best describes a polymorphism in the context of genetics?

Accepted Answer

A variation of gene or marker sequence present in $$\u003e1\% of $$the population.

Question 2

A restriction enzyme recognizes the sequence $$5'	ext{-}AGATCT	ext{-}3'$$ and cuts at this site. If a mutation removes one of these sites in a gene, what would be the effect on the DNA fragments after digestion and gel electrophoresis?

Accepted Answer

The DNA will have fewer fragments, and the remaining fragments will be larger.

Question 3

In the mouse RFLP gel (third image), what genotype corresponds to a single 380 bp band?

Accepted Answer

Homozygous for the bent tail allele ($$tt)$$

Question 4

A PCR reaction requires which of the following components?

Accepted Answer

DNA template, primers, dNTPs, and Taq polymerase

Question 5

In the PRL gene gel (sixth image), which cow(s) would have the greatest milk production?

Accepted Answer

Cow(s) with genotype $$MM$$

Question 6

If individual 5 (genotype $$Dd) $$mates with individual 8 ($$dd) in $$the fourth gel image, what proportion of their children will be affected by the autosomal recessive disorder?

Accepted Answer

$$50\%$$ will be affected ($$dd)$$

Question 7

Which of the following best describes the principle behind gel electrophoresis?

Accepted Answer

DNA fragments are separated by size as they migrate through an agarose gel.

Question 8

In the BRCA-1 pedigree and gel (ninth image), what is the most likely genotype of individual III-1 based on the RFLP analysis?

Accepted Answer

Heterozygous ($$Bb)$$

Question 9

Which of the following statements about RFLP analysis is correct?

Accepted Answer

RFLP analysis detects specific DNA restriction fragment patterns in DNA samples.

Question 10

A crime scene DNA sample matches the RFLP pattern of Suspect B (last image). What does this suggest?

Accepted Answer

Suspect B is likely to have committed the crime.

Question 11

If a restriction enzyme site is lost due to a SNP, what is the most likely outcome in a PCR-RFLP analysis?

Accepted Answer

The PCR product will not be cut, resulting in a single larger band.

Question 12

Which of the following is NOT required for a successful PCR reaction?

Accepted Answer

Restriction enzyme

Question 13

In the context of the PRL gene, what is the expected band pattern for a cow with genotype $$Mm$$ after HaeIII digestion?

Accepted Answer

One 700 bp band and two bands at 400 bp and 300 bp

Question 14

A baby is suspected of having congenital lactose intolerance. If the PCR-RFLP gel shows only one BglII site, what does this indicate?

Accepted Answer

The baby is homozygous for the lactose intolerance allele.

Question 15

Which of the following best describes a haplotype?

Accepted Answer

A group of alleles inherited together from a single parent.

Question 16

If a mouse is heterozygous for the bent tail allele ($$Tt$$), what bands will appear on the gel after HindIII digestion?

Accepted Answer

Bands at 380 bp, 270 bp, and 110 bp

Question 17

Which of the following is a plausible explanation for why you would never see only the 700 bp fragment in the PRL gene gel (sixth image) if there are no new mutations?

Accepted Answer

Because the 700 bp fragment is only present in the homozygous B form ($$mm$$), and the primers amplify both alleles.

Question 18

Which of the following best describes the function of Taq polymerase in PCR?

Accepted Answer

It synthesizes new DNA strands from the template at high temperatures.

Question 19

In the BRCA-1 gene diagram (eighth image), what is the size of the PCR fragment amplified from the mutant allele before digestion?

Accepted Answer

$$1.9\ 	ext{kb}$$

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