Question 1

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

Accepted Answer

Information flows from DNA to RNA to protein.

Question 2

During DNA replication in bacteria, which enzyme is primarily responsible for synthesizing the majority of the new DNA strand?

Accepted Answer

DNA polymerase III

Question 3

Which of the following is a key difference between bacterial and eukaryotic genomes?

Accepted Answer

Bacterial genomes are typically circular and have a single origin of replication, while eukaryotic genomes are linear and have multiple origins of replication.

Question 4

What is the function of single-strand binding proteins during DNA replication?

Accepted Answer

They stabilize unwound DNA strands to prevent them from re-annealing.

Question 5

A researcher is looking for the origin of replication (oriC) in a bacterial genome. Which feature should they look for?

Accepted Answer

A region with DnaA binding sites and a high proportion of A=T base pairs.

Question 6

Which of the following best explains why DNA replication proceeds in the 5' to 3' direction?

Accepted Answer

DNA polymerase requires a free 3'-OH group to add new nucleotides.

Question 7

Which enzyme is responsible for removing RNA primers and replacing them with DNA during bacterial DNA replication?

Accepted Answer

DNA polymerase I

Question 8

In the context of bacterial cell walls, what is the primary function of peptidoglycan?

Accepted Answer

It provides structural strength and determines cell shape.

Question 9

Which of the following statements about plasmids is correct?

Accepted Answer

Plasmids are extrachromosomal DNA elements that often carry antibiotic resistance genes.

Question 10

A mutation in the gene encoding DNA ligase would most directly affect which process during DNA replication?

Accepted Answer

Joining Okazaki fragments on the lagging strand.

Question 11

Which of the following best describes the structure of peptidoglycan in bacterial cell walls?

Accepted Answer

A mesh-like polymer of sugars and amino acids with glycosidic bonds and peptide crosslinks.

Question 12

Which component of the Gram-negative bacterial cell envelope is often toxic to animals and is known as an endotoxin?

Accepted Answer

Lipid A of the lipopolysaccharide (LPS) layer

Question 13

A scientist is comparing the genomes of E. coli and humans. Which of the following is true?

Accepted Answer

The human genome is much larger, with approximately 3200 Mbp and ~20,000 genes, compared to E. coli's 4.64 Mbp and fewer genes.

Question 14

Which of the following best explains why the origin of replication (oriC) in bacteria is rich in A=T base pairs?

Accepted Answer

A=T base pairs have two hydrogen bonds, making them easier to separate than G≡C base pairs.

Question 15

Which of the following is NOT a function of the bacterial S-layer?

Accepted Answer

Energy production via ATP synthesis.

Question 16

During DNA replication, which of the following equations best represents the addition of a nucleotide to the growing DNA strand?

Accepted Answer

$$(DNA)_{(n)} + dNTP \rightarrow (DNA)_{(n+1)} + PP_i$$

Question 17

Which of the following statements about Okazaki fragments is correct?

Accepted Answer

They are short DNA fragments synthesized on the lagging strand during DNA replication.

Question 18

A patient is infected with a Gram-negative bacterium. Which cell envelope component is most likely to trigger a strong immune response?

Accepted Answer

Lipopolysaccharide (LPS) layer

Question 19

Which of the following best describes the role of primase during DNA replication?

Accepted Answer

It synthesizes short RNA primers needed for DNA polymerase to begin synthesis.

Question 20

Which of the following is a correct statement about the directionality of DNA synthesis?

Accepted Answer

DNA synthesis occurs in the 5' to 3' direction on both the leading and lagging strands.

Cell Biology II: DNA Structure, Function, and Replication in Microbiology

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