$$1 \text{ mistake per } 10^9$ \text{ nucleotides copied}$$

Question 1

Which of the following best describes a frameshift mutation and its likely effect on protein synthesis?

Accepted Answer

A mutation that inserts or deletes a nucleotide, shifting the reading frame and usually resulting in a nonfunctional protein.

Question 2

A patient with Marfan syndrome has one mutated and one normal FBN1 allele. This is an example of which genetic phenomenon?

Accepted Answer

Haploinsufficiency

Question 3

Which of the following mutations is most likely to result from exposure to UV light?

Accepted Answer

Thymine dimer formation

Question 4

A DNA sequence changes from 5'-ATG GCA-3' to 5'-ATG TCA-3'. What type of mutation has occurred?

Accepted Answer

Transversion

Question 5

Which of the following best explains why RNA viruses, such as HIV, evolve more rapidly than DNA viruses?

Accepted Answer

RNA viruses lack proofreading mechanisms, leading to higher mutation rates.

Question 6

What is the main consequence of a nonsense mutation in a coding region?

Accepted Answer

The protein is truncated due to a premature stop codon.

Question 7

Which DNA repair mechanism is responsible for correcting mismatches that escape proofreading during DNA replication?

Accepted Answer

Mismatch repair

Question 8

A mutation changes a codon from GAA (Glu) to GAG (Glu). What type of mutation is this?

Accepted Answer

Silent (synonymous) mutation

Question 9

Which of the following best describes the 'wobble' hypothesis in translation?

Accepted Answer

The third base of the codon can pair flexibly with the first base of the tRNA anticodon, allowing one tRNA to recognize multiple codons.

Question 10

Which of the following is a likely outcome of a dominant negative mutation in the p53 tumor suppressor gene?

Accepted Answer

The mutant p53 subunit disrupts the function of the wild-type subunits, leading to loss of tumor suppressor activity.

Question 11

Which of the following equations best represents the error rate of DNA replication with proofreading and mismatch repair?

Accepted Answer

$$1 	ext{ mistake per } 10^9$ 	ext{ nucleotides copied}$$

Question 12

Which of the following best describes a conservative missense mutation?

Accepted Answer

A mutation that changes an amino acid to one with similar properties, often preserving protein function.

Question 13

Which of the following is a real-life example of a disease caused by a dominant mutation due to haploinsufficiency?

Accepted Answer

Marfan syndrome

Question 14

Which of the following mutagens is most likely to cause single-nucleotide insertions or deletions during DNA replication?

Accepted Answer

Intercalating agents

Question 15

A cytosine in DNA undergoes deamination. What is the most likely base pairing that will occur after this event if not repaired?

Accepted Answer

Uracil will pair with adenine

Question 16

Which of the following best explains why a mutation in the third position of a codon often does not change the encoded amino acid?

Accepted Answer

The genetic code is degenerate, and the third position often allows for wobble pairing.

Question 17

Which of the following is a likely effect of phosphorylation of eIF2α during cellular stress?

Accepted Answer

Decreased translation initiation, conserving cellular resources

Question 18

Which of the following best describes the effect of a loss-of-function mutation in a tumor suppressor gene?

Accepted Answer

It results in decreased or absent gene activity, potentially allowing cancer development.

Question 19

Which of the following is a key difference between transitions and transversions?

Accepted Answer

Transitions involve purine-purine or pyrimidine-pyrimidine swaps, while transversions involve purine-pyrimidine swaps.

Mutations and DNA Repair: Mechanisms, Types, and Biological Consequences

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