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

Which of the following features is essential for a eukaryotic gene to be transcribed and translated?

Accepted Answer

A promoter region upstream of the coding sequence

Question 3

Which of the following statements correctly distinguishes between transcription and translation?

Accepted Answer

Transcription copies the DNA sequence into RNA, while translation converts the RNA sequence into a polypeptide chain.

Question 4

Which of the following is an extension of the central dogma that is utilized by retroviruses such as HIV?

Accepted Answer

Reverse transcription ($$RNA \rightarrow DNA)$$

Question 5

The Meselson and Stahl experiment demonstrated that DNA replication is semi-conservative. Which result from their experiment supported this model?

Accepted Answer

After one round of replication in $$^{14}N$$ medium, all DNA had intermediate density between $$^{15}N$$ and $$^{14}N.$$

Question 6

During DNA replication, which enzyme is responsible for synthesizing short RNA primers required for DNA polymerase to begin synthesis?

Accepted Answer

Primase

Question 7

Why is DNA polymerase unable to replicate the very ends of linear chromosomes, and how is this problem solved in eukaryotic cells?

Accepted Answer

DNA polymerase requires a primer and cannot fill in the gap left after primer removal; telomerase extends the 3' end using an RNA template.

Question 8

Which of the following best describes the chemical reaction that occurs during DNA polymerization?

Accepted Answer

A phosphodiester bond forms between the 3' hydroxyl group of the growing DNA strand and the 5' phosphate of the incoming nucleotide, releasing pyrophosphate ($$PP_i).$$

Question 9

A patient is found to have a mutation in the gene encoding DNA ligase. Which of the following processes would be most directly affected?

Accepted Answer

Joining of Okazaki fragments on the lagging strand during DNA replication

Question 10

Which of the following statements about telomerase is TRUE?

Accepted Answer

Telomerase is active in germline cells and some cancer cells, but not in most somatic cells.

Question 11

Which of the following best explains why transitions are more common than transversions in DNA mutations?

Accepted Answer

Transitions involve substitution of a purine for another purine or a pyrimidine for another pyrimidine, which causes less structural distortion of the DNA helix.

Question 12

A mutation in a proto-oncogene is most likely to result in which of the following?

Accepted Answer

A gain-of-function mutation that promotes uncontrolled cell division

Question 13

In the context of the 'two-hit' model for cancer development, which of the following is TRUE?

Accepted Answer

Both alleles of a tumor suppressor gene must be inactivated for cancer to develop.

Question 14

During transcription in prokaryotes, what is the role of the sigma factor?

Accepted Answer

It helps RNA polymerase recognize and bind to the promoter region to initiate transcription.

Question 15

Which of the following is a key difference between transcription initiation in eukaryotes and prokaryotes?

Accepted Answer

Eukaryotes require multiple transcription factors and a TATA box, while prokaryotes use a sigma factor.

Question 16

Which of the following correctly matches a feature of eukaryotic mRNA processing with its function?

Accepted Answer

Addition of a 5' cap protects mRNA from degradation and assists in ribosome binding.

Question 17

Alternative splicing is important because it:

Accepted Answer

Allows a single gene to produce multiple protein isoforms.

Question 18

During translation, which site of the ribosome does the incoming aminoacyl-tRNA first bind?

Accepted Answer

A-site

Question 19

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

Accepted Answer

It is degenerate, meaning that multiple codons can specify the same amino acid.

Question 20

A mutation shifts the reading frame of a gene by deleting one nucleotide. What is the likely consequence for the resulting protein?

Accepted Answer

A frameshift mutation will alter all downstream amino acids, likely resulting in a nonfunctional protein.

Study Guide: Central Dogma, DNA Replication, Mutation, Transcription, RNA Processing, Translation, and Genetic Code

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