Question 1

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

The unidirectional flow of genetic information from DNA to RNA to protein.

Question 2

During transcription, which enzyme is responsible for synthesizing RNA from a DNA template?

Accepted Answer

RNA polymerase

Question 3

A mutation changes the DNA sequence 5'-ATG-3' (coding strand) to 5'-ATA-3'. What is the effect on the protein sequence, given that AUG codes for methionine and AUA codes for isoleucine?

Accepted Answer

A missense mutation; methionine is replaced by isoleucine.

Question 4

Which of the following modifications occurs to eukaryotic pre-mRNA before it becomes mature mRNA?

Accepted Answer

Addition of a 5' cap and a poly-A tail

Question 5

Given the DNA template strand 3'-TACGGTACG-5', what is the corresponding mRNA sequence?

Accepted Answer

5'-AUGCCAUGC-3'

Question 6

Which of the following statements about the genetic code is correct?

Accepted Answer

It is redundant, meaning multiple codons can code for the same amino acid.

Question 7

Which type of RNA carries amino acids to the ribosome during translation?

Accepted Answer

tRNA

Question 8

A ribosome has three tRNA binding sites. Which site holds the tRNA carrying the growing polypeptide chain?

Accepted Answer

P-site

Question 9

Which of the following mutations is most likely to result in a nonfunctional protein if it occurs near the start of the coding sequence?

Accepted Answer

A deletion of one nucleotide

Question 10

What is the function of the release factor during translation?

Accepted Answer

It binds to the stop codon in the A site in place of a tRNA.

Question 11

Which of the following is a reversible post-translational modification that can activate or deactivate a protein?

Accepted Answer

Phosphorylation

Question 12

Which of the following sequences of nucleotides in the template strand of DNA would code for the polypeptide sequence Phe–Leu–Ile–Val?

Accepted Answer

3'-AAA-GAA-TAA-CAA-5'

Question 13

Which of the following processes occurs in eukaryotic gene expression but not in prokaryotic gene expression?

Accepted Answer

RNA splicing

Question 14

A section of DNA has this base sequence: AGCGTTACCGT. A mutation in this DNA strand results in this base sequence: AGGCGTTACCGT. What type of mutation does this change represent?

Accepted Answer

Frameshift mutation

Question 15

Which of the following statements about transcription in eukaryotes is true?

Accepted Answer

Transcription factors are required for RNA polymerase to bind to the promoter.

Question 16

What is the correct order of events during the elongation phase of translation?

Accepted Answer

A charged tRNA enters the A site, a peptide bond is formed, the polypeptide is transferred to the tRNA in the A site, and the ribosome shifts.

Question 17

Which of the following properties is NOT shared by RNA polymerase and DNA polymerase?

Accepted Answer

Can initiate strand synthesis

Question 18

A nonsense mutation:

Accepted Answer

Causes synthesis of a polypeptide chain to be terminated prematurely.

Question 19

Which of the following statements about ribosomes is true?

Accepted Answer

Several ribosomes can translate the same mRNA simultaneously.

Question 20

Which of the following best explains why a single base substitution is LEAST likely to be deleterious when the change results in replacement of a codon specifying an amino acid with a redundant codon specifying the same amino acid?

Accepted Answer

The amino acid sequence of the protein remains unchanged.

Gene Expression: From DNA to Protein

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