Question 1

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

Accepted Answer

It catalyzes the formation of peptide bonds between amino acids.

Question 2

A mutation changes the third base of a codon from C to U. Which concept explains why this may not change the amino acid specified?

Accepted Answer

Third-base wobble

Question 3

Which amino acid is always the first incorporated into a newly synthesized polypeptide in eukaryotes?

Accepted Answer

Methionine

Question 4

What is the function of the Shine-Dalgarno sequence in bacterial translation?

Accepted Answer

It serves as a binding site for the ribosome to initiate translation.

Question 5

Which of the following best describes a polyribosome?

Accepted Answer

A group of ribosomes translating the same mRNA simultaneously.

Question 6

Which phase of translation involves the recruitment of elongation factor proteins and GTP hydrolysis?

Accepted Answer

Elongation

Question 7

A bacterial cell is observed to have a mutation in the gene encoding IF2. What process would be most directly affected?

Accepted Answer

Ribosome assembly during initiation

Question 8

Which equation correctly represents the formation of a peptide bond between two amino acids?

Accepted Answer

$$\mathrm{Amino\ acid}_1 + \mathrm{Amino\ acid}_2 \rightarrow \mathrm{Dipeptide} + H_2O$$

Question 9

Which of the following is true regarding the genetic code?

Accepted Answer

It is universal, with only a few exceptions in mitochondria and some nuclear DNA.

Question 10

What is the role of aminoacyl-tRNA synthetase in translation?

Accepted Answer

It attaches the correct amino acid to its corresponding tRNA.

Question 11

Which of the following best explains why frameshift mutations can have severe effects on protein function?

Accepted Answer

They alter the reading frame, causing all downstream codons to be misread.

Question 12

Which region of the ribosome is responsible for holding the tRNA to which the growing polypeptide is attached?

Accepted Answer

P site

Question 13

During eukaryotic translation initiation, which sequence is recognized to locate the start codon?

Accepted Answer

Kozak sequence

Question 14

Which of the following amino acids has a nonpolar side chain?

Accepted Answer

Leucine

Question 15

What is the main difference between monocistronic and polycistronic mRNA?

Accepted Answer

Monocistronic mRNA encodes one protein, while polycistronic encodes several.

Question 16

Which of the following is a common posttranslational modification that can activate or inactivate a protein?

Accepted Answer

Phosphorylation

Question 17

A scientist observes that a protein destined for secretion is translated at the rough ER. What sequence is most likely present at the N-terminus of this protein?

Accepted Answer

A signal sequence of 15-20 amino acids

Question 18

Which release factor in bacteria recognizes both UAA and UGA stop codons?

Accepted Answer

RF2

Question 19

Which equation best represents the number of possible codons in the genetic code, given four nucleotide bases and a triplet code?

Accepted Answer

$$4^3 = 64$

Question 20

Which experimental result provided conclusive evidence that the genetic code is nonoverlapping?

Accepted Answer

Single nucleotide changes led to single amino acid changes.

Chapter 9: The Molecular Biology of Translation – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard