Question 1

Which of the following best describes the function of the wobble position in the genetic code?

Accepted Answer

It allows tRNAs to recognize multiple codons for the same amino acid, increasing translation efficiency.

Question 2

A mutation changes the sixth codon of the β-globin gene from GAG to GTG. What is the consequence of this mutation?

Accepted Answer

Glutamic acid is replaced by valine, causing hemoglobin molecules to aggregate and leading to sickle cell disease.

Question 3

Which equation represents the dehydration reaction that forms a peptide bond between two amino acids?

Accepted Answer

$$\mathrm{R{-}CH(NH_2$){-}COOH} + \mathrm{R'{-}CH(NH_2$){-}COOH} \rightarrow \mathrm{R{-}CH(NH_2$){-}CONH{-}CH(R'){COOH}} + \mathrm{H_2O}$$

Question 4

Which of the following is a key difference between bacterial and eukaryotic translation initiation?

Accepted Answer

Bacterial mRNAs use the Shine–Dalgarno sequence to position the ribosome, while eukaryotic mRNAs use the Kozak sequence and a 5' cap.

Question 5

Which post-translational modification tags proteins for degradation by the proteasome?

Accepted Answer

Ubiquitination

Question 6

A protein destined for secretion from a eukaryotic cell is most likely to contain which of the following?

Accepted Answer

An N-terminal signal sequence recognized by the signal recognition particle (SRP)

Question 7

Which of the following statements about tRNA is correct?

Accepted Answer

tRNAs undergo extensive post-transcriptional modifications, including base modifications, trimming, and addition of a CCA tail.

Question 8

Which of the following best explains the effect of an insertion mutation in an mRNA sequence?

Accepted Answer

It can cause a frameshift, altering the reading frame and potentially introducing premature stop codons, resulting in a truncated protein.

Question 9

Which of the following is NOT a function of post-translational modifications?

Accepted Answer

Directing ribosome assembly on mRNA

Question 10

Which equation represents the energy requirement for aminoacyl-tRNA synthetase activity?

Accepted Answer

$$\mathrm{ATP} \rightarrow \mathrm{AMP} + 2\,\mathrm{P_i}$$

Question 11

Which of the following best describes the role of the ribosome during translation?

Accepted Answer

It provides sites for mRNA binding and catalyzes peptide bond formation between amino acids.

Question 12

Which of the following is a consequence of the degeneracy of the genetic code?

Accepted Answer

Multiple codons can specify the same amino acid, reducing the impact of some mutations.

Question 13

Which of the following is a function of protein domains?

Accepted Answer

They impart distinct functional capabilities, such as DNA binding, ligand binding, or protein-protein interaction.

Question 14

Which of the following is true regarding ribosomal DNA (rDNA) in humans?

Accepted Answer

rDNA genes are organized in clusters on the short arms of acrocentric chromosomes and are separated by noncoding spacer DNA.

Question 15

Which of the following best describes the process of translation elongation in bacteria?

Accepted Answer

Charged tRNAs enter the A site, peptide bonds form, and the ribosome translocates along the mRNA, repeating the cycle until a stop codon is reached.

Question 16

Which of the following is a real-world consequence of abnormal protein folding due to environmental conditions?

Accepted Answer

Proteins may become dysfunctional, leading to diseases such as cystic fibrosis or Alzheimer's.

Question 17

Which of the following best explains the role of the Kozak sequence in eukaryotic translation?

Accepted Answer

It helps the ribosome recognize the correct start codon, increasing translation initiation efficiency.

Question 18

Which of the following is a function of the poly-A tail in eukaryotic mRNA?

Accepted Answer

It plays a role in translation initiation and mRNA stability.

Question 19

Which of the following best describes the effect of K48-linked polyubiquitination?

Accepted Answer

It targets proteins for degradation by the proteasome.

Translation and Post-Translational Modifications in Genetics

Study Guide - Practice Questions