Question 1

Which of the following best describes the Central Dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 2

A mutation in the DNA sequence changes a codon from GAG to GTG in the β-globin gene. What is the consequence of this mutation at the protein level, and what disease can it cause?

Accepted Answer

It changes a glutamic acid to a valine, causing sickle cell anemia.

Question 3

Which property of the genetic code allows multiple codons to specify the same amino acid?

Accepted Answer

Redundancy (degeneracy)

Question 4

In prokaryotes, what is the sequence called that helps the ribosome bind to the mRNA and position it correctly for translation initiation?

Accepted Answer

Shine-Dalgarno sequence

Question 5

Which of the following statements about tRNA is FALSE?

Accepted Answer

tRNA molecules are translated into proteins.

Question 6

Which of the following best explains why the genetic code is considered non-overlapping?

Accepted Answer

Each base is part of only one codon and is read only once during translation.

Question 7

A researcher adds a synthetic mRNA composed entirely of repeating UCUCUCUC... to a cell-free translation system. Which of the following polypeptide sequences is most likely to be produced?

Accepted Answer

A polypeptide with alternating serine and leucine residues.

Question 8

Which of the following is the correct order of events during translation elongation in prokaryotes?

Accepted Answer

tRNA binding to A site, peptide bond formation, translocation

Question 9

Which of the following statements about the ribosome is TRUE?

Accepted Answer

The ribosome's peptidyl transferase activity is carried out by rRNA.

Question 10

A mutation causes the insertion of a single nucleotide into a coding sequence. What is the most likely effect on the resulting protein?

Accepted Answer

A frameshift mutation, altering all downstream amino acids.

Question 11

Which of the following best describes the 'wobble' hypothesis in tRNA-codon pairing?

Accepted Answer

The third base of the codon can pair with multiple bases in the anticodon, allowing one tRNA to recognize several codons.

Question 12

Which of the following is NOT a function of the ribosome during translation?

Accepted Answer

Charging tRNAs with their respective amino acids.

Question 13

In eukaryotes, what is the main difference in translation initiation compared to prokaryotes?

Accepted Answer

Eukaryotic ribosomes bind to the 5' cap and scan for the first AUG codon.

Question 14

Which of the following codons is the start codon for translation in most organisms?

Accepted Answer

$$\mathrm{AUG}$$

Question 15

A polypeptide is synthesized with the following sequence: Met-Ser-Gly-Stop. Which mRNA sequence could code for this polypeptide?

Accepted Answer

$$\mathrm{AUG\ UCU\ GGU\ UAA}$$

Question 16

Which of the following best explains why three base insertions or deletions can restore the wild-type phenotype in the Crick and Brenner experiment?

Accepted Answer

The genetic code is triplet, so three insertions or deletions restore the reading frame.

Question 17

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

Accepted Answer

It is ambiguous (each codon codes for more than one amino acid).

Question 18

During translation termination, what recognizes the stop codon in the A site of the ribosome?

Accepted Answer

A release factor protein

Question 19

Which of the following best describes the direction in which the ribosome reads the mRNA during translation?

Accepted Answer

5' to 3'

Question 20

Which of the following is a real-world consequence of a single amino acid substitution in a protein, as seen in sickle cell anemia?

Accepted Answer

Altered hemoglobin structure leads to aggregation and sickling of red blood cells.

Translation: The Molecular Biology of Protein Synthesis

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