Question 1

Which of the following best describes the degeneracy of the genetic code?

Accepted Answer

A single amino acid can be specified by more than one codon.

Question 2

A mutation changes the codon UAU (tyrosine) to UAA in an mRNA sequence. What type of mutation is this, and what is the likely effect on the protein?

Accepted Answer

Nonsense mutation; results in early termination of translation.

Question 3

Which of the following is the correct tRNA anticodon (written 5' to 3') that would pair with the mRNA codon 5'-AUG-3'?

Accepted Answer

5'-UAC-3'

Question 4

In the presence of the antibiotic streptolydigin, prokaryotic RNA polymerase binds to promoters but cannot polymerize RNA. What is the most likely mechanism by which this antibiotic inhibits transcription?

Accepted Answer

Blocks the catalytic activity of the polymerase

Question 5

A patient with sickle-cell anemia has a single nucleotide change in the HBB gene, resulting in a different amino acid in the hemoglobin protein. What type of mutation is this?

Accepted Answer

Missense mutation

Question 6

Which of the following statements about translation in prokaryotes and eukaryotes is correct?

Accepted Answer

In prokaryotes, translation can begin before transcription is complete.

Question 7

A frameshift mutation occurs when a single nucleotide is inserted into a coding sequence. What is the most likely consequence for the resulting protein?

Accepted Answer

The reading frame is altered, changing all downstream amino acids.

Question 8

Which of the following codons is recognized as a start codon in nearly all organisms?

Accepted Answer

$$\mathrm{AUG}$$

Question 9

A mutation in the aminoacyl tRNA synthetase for valine causes it to attach glycine to tRNA^Val instead of valine. What will happen during translation?

Accepted Answer

Glycine will be incorporated at all valine codons.

Question 10

Which of the following best explains the wobble hypothesis?

Accepted Answer

The third base of the codon is less spatially constrained and can pair with multiple bases.

Question 11

Given the mRNA sequence 5'-AUGGCAAAAAAGUGA-3', what is the resulting amino acid sequence?

Accepted Answer

Met-Ala-Lys-Lys

Question 12

Which of the following is NOT a feature of the genetic code?

Accepted Answer

It is overlapping.

Question 13

Which of the following posttranslational modifications is most likely to affect the function of a protein?

Accepted Answer

Addition of a phosphate group to a serine residue

Question 14

Which of the following best describes the role of ribosomes in translation?

Accepted Answer

They catalyze the formation of peptide bonds between amino acids.

Question 15

Which of the following is a real-world example of the universality of the genetic code?

Accepted Answer

A gene from a jellyfish can be expressed in bacteria to produce green fluorescent protein.

Question 16

Which of the following is a direct result of a nonsense mutation in a gene?

Accepted Answer

A shorter, likely nonfunctional protein is produced.

Question 17

Which of the following is true regarding the initiation of translation in eukaryotes?

Accepted Answer

The ribosome recognizes the Kozak sequence near the start codon.

Question 18

Which of the following best explains why polyribosomes (polysomes) are advantageous for cells?

Accepted Answer

They allow multiple copies of a protein to be synthesized from a single mRNA simultaneously.

Question 19

Which of the following is a property of the primary structure of a protein?

Accepted Answer

The sequence of amino acids in the polypeptide chain

Question 20

A mutation changes the codon GAA (glutamic acid) to GAG (also glutamic acid). What type of mutation is this?

Accepted Answer

Silent mutation

The Genetic Code and Translation: Structure, Function, and Mechanisms

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