Question 1

Which of the following best describes the primary difference between bacterial chromosomes and plasmids?

Accepted Answer

Bacterial chromosomes are circular and contain essential genes, while plasmids are smaller, circular DNA molecules that often carry non-essential genes such as those for antibiotic resistance.

Question 2

During DNA replication in bacteria, why is an RNA primer required?

Accepted Answer

DNA polymerase can only add nucleotides to an existing 3’-OH group, which is provided by the RNA primer.

Question 3

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

Accepted Answer

DNA polymerase I

Question 4

What is the function of the 3’ to 5’ exonuclease activity of DNA polymerase III in bacteria?

Accepted Answer

It removes mismatched bases during DNA replication, providing proofreading capability.

Question 5

Which of the following statements about bacterial transcription is correct?

Accepted Answer

The sigma subunit of RNA polymerase recognizes the promoter and is required for transcription initiation.

Question 6

Which feature distinguishes Rho-independent transcription termination in bacteria?

Accepted Answer

A stem-loop structure forms in the nascent mRNA, causing RNA polymerase to dissociate.

Question 7

Which of the following best explains why DNA polymerase from Thermus aquaticus (Taq) is used in PCR instead of E. coli DNA polymerase?

Accepted Answer

Taq polymerase is stable and active at the high temperatures required for PCR denaturation steps.

Question 8

Which of the following is a key difference between translation initiation in Bacteria and Eukarya?

Accepted Answer

Bacteria use a ribosome binding site (Shine-Dalgarno sequence) and fMet-tRNA, while Eukarya use a 5’ cap and Met-tRNA.

Question 9

Which of the following best describes the role of aminoacyl-tRNA synthetases in translation?

Accepted Answer

They attach the correct amino acid to its corresponding tRNA using ATP.

Question 10

A mutation in the gene encoding a bacterial molecular chaperone such as GroEL would most likely result in which phenotype under heat shock conditions?

Accepted Answer

Increased protein misfolding and aggregation.

Question 11

Which of the following is true regarding the Type III secretion system in pathogenic bacteria?

Accepted Answer

It delivers protein exotoxins directly into host cells using a needle-like structure.

Question 12

Which of the following best explains why supercoiling of bacterial chromosomes is medically important?

Accepted Answer

Drugs that target DNA gyrase, which regulates supercoiling, can inhibit bacterial growth.

Question 13

Which of the following statements about the flow of genetic information in cells is correct?

Accepted Answer

Translation is the process of synthesizing protein from an mRNA template.

Question 14

Which of the following is a function of DNA ligase during DNA replication?

Accepted Answer

Joining Okazaki fragments by forming covalent bonds between adjacent DNA fragments.

Question 15

Which of the following best describes the structure of a bacterial operon?

Accepted Answer

A cluster of genes under the control of a single promoter and terminator, often encoding proteins for a common pathway.

Question 16

Which of the following is a key difference between transcription in Archaea and Bacteria?

Accepted Answer

Archaea use general transcription factors (TBP and TFB) instead of sigma factors for promoter recognition.

Question 17

Which of the following equations correctly represents the energy-releasing reaction during DNA synthesis?

Accepted Answer

$$\mathrm{(dNMP)_n + dNTP \rightarrow (dNMP)_{n+1} + PP_i}$$

Question 18

Which of the following is a real-world consequence of mutations in the genes encoding ribosomal RNA in bacteria?

Accepted Answer

The bacteria may become resistant to antibiotics that target the ribosome, such as aminoglycosides.

Question 19

Which of the following best describes the role of the Shine-Dalgarno sequence in bacterial translation?

Accepted Answer

It helps the ribosome recognize and bind to the start site of mRNA for translation initiation.

Molecular Information Flow and Protein Processing in Microbial Cells Ch 6

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