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 changes the DNA sequence from $$	ext{TAC} to$$ $$	ext{TAA} in $$the coding strand. What is the effect on the resulting protein, using the standard genetic code?

Accepted Answer

The start codon is replaced by a stop codon, likely truncating the protein.

Question 3

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

Accepted Answer

The genetic code is overlapping, so one nucleotide can be part of multiple codons.

Question 4

In prokaryotic transcription, what is the function of the sigma factor?

Accepted Answer

It binds to the promoter to help RNA polymerase recognize where to start transcription.

Question 5

Which of the following is a direct result of alternative splicing in eukaryotes?

Accepted Answer

A single gene can produce multiple protein isoforms.

Question 6

During transcriptional elongation, which direction is the RNA transcript synthesized?

Accepted Answer

5’ to 3’

Question 7

Which of the following modifications is added to the 5’ end of eukaryotic mRNA to protect it from degradation and assist in translation initiation?

Accepted Answer

7-methylguanosine cap

Question 8

A scientist discovers a mitochondrial gene in humans where the codon UGA codes for tryptophan instead of a stop signal. What does this illustrate?

Accepted Answer

There are exceptions to the universal genetic code.

Question 9

Which of the following best explains why DNA is not directly used for protein synthesis in the cytoplasm?

Accepted Answer

DNA must remain in the nucleus to protect the genetic information and allow for multiple RNA copies to be made as needed.

Question 10

Which of the following is NOT a function of tRNA?

Accepted Answer

Encoding the sequence that the ribosome will translate into a polypeptide.

Question 11

A mutation in the promoter region of a gene most likely affects which stage of transcription?

Accepted Answer

Initiation

Question 12

Which of the following best describes the process of Rho-independent (intrinsic) termination in prokaryotic transcription?

Accepted Answer

A hairpin loop followed by a U-rich sequence causes RNA polymerase to pause and the RNA-DNA hybrid to dissociate.

Question 13

Which of the following is a real-world example of RNA editing in humans?

Accepted Answer

A cytosine in the Apolipoprotein B mRNA is changed to uracil, creating a premature stop codon in the intestine.

Question 14

Which of the following statements about eukaryotic RNA polymerases is correct?

Accepted Answer

RNA polymerase II transcribes all structural genes and some snRNAs.

Question 15

Which of the following chromatin modifications would most likely enhance gene expression?

Accepted Answer

Acetylation of histones, reducing their positive charge and loosening DNA-histone interaction.

Question 16

A eukaryotic pre-mRNA is processed to mature mRNA by all of the following EXCEPT:

Accepted Answer

Removal of exons.

Question 17

Which of the following best explains the role of the Shine-Dalgarno sequence in prokaryotic mRNA?

Accepted Answer

It is the site where the ribosome binds to initiate translation.

Question 18

If a mutation causes the loss of function of the TFIIH complex in eukaryotes, which process would be most directly affected?

Accepted Answer

Formation of the open complex during transcription initiation.

Question 19

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

Accepted Answer

Multiple codons can code for the same amino acid.

Question 20

Which of the following best describes the relationship between the coding strand of DNA and the mRNA transcript?

Accepted Answer

The mRNA is identical to the coding strand except that uracil (U) replaces thymine (T).

Genetic Code and Transcription: Structure, Function, and Regulation

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