$$TI = \frac{\text{toxic dose}}{\text{effective dose}}$$

Question 1

Which enzyme is responsible for relieving supercoiling tension ahead of the replication fork during DNA replication in prokaryotes?

Accepted Answer

Topoisomerase (gyrase)

Question 2

During DNA replication, the lagging strand is synthesized discontinuously. What are the short fragments called that are produced on this strand?

Accepted Answer

Okazaki fragments

Question 3

In transcription, which of the following best describes the role of the sigma ($$\sigma) $$factor in prokaryotes?

Accepted Answer

It initiates RNA polymerase binding to the promoter

Question 4

Which of the following statements about translation initiation in prokaryotes is correct?

Accepted Answer

The small ribosomal subunit recognizes the Shine-Dalgarno sequence

Question 5

A researcher is testing the effectiveness of a new antibiotic. The minimum concentration that prevents visible bacterial growth is called:

Accepted Answer

Minimum Inhibitory Concentration (MIC)

Question 6

Which of the following is a correct equation for calculating the Therapeutic Index (TI) of a drug?

Accepted Answer

$$TI = \frac{	ext{toxic dose}}{	ext{effective dose}}$$

Question 7

Which of the following antibiotics targets peptidoglycan synthesis in bacteria?

Accepted Answer

Penicillin

Question 8

A mutation disables the lac repressor in E. coli. What is the most likely consequence for the lac operon?

Accepted Answer

The operon will be constitutively expressed, even without lactose

Question 9

Which of the following statements about prokaryotic ribosomes is correct?

Accepted Answer

They are composed of 30S and 50S subunits

Question 10

Which process is most commonly used by bacteria for cell division?

Accepted Answer

Binary fission

Question 11

Which of the following statements about endospores is true?

Accepted Answer

Endospores are resistant structures formed by Bacillus and Clostridium

Question 12

Which of the following is a unique feature of archaeal cell membranes compared to bacterial membranes?

Accepted Answer

Ether-linked lipids

Question 13

Which of the following correctly describes the direction of DNA synthesis during replication?

Accepted Answer

$$5' \rightarrow 3'$$

Question 14

A patient is infected with a Gram-negative bacterium. Which antibiotic class would be LEAST effective due to the outer membrane barrier?

Accepted Answer

Glycopeptides (e.g., vancomycin)

Question 15

Which of the following is a correct sequence of events in prokaryotic transcription termination by the Rho-dependent mechanism?

Accepted Answer

Rho protein binds to a specific RNA sequence, displaces RNA polymerase, and releases the mRNA

Question 16

Which of the following is NOT a function of eukaryotic mRNA processing?

Accepted Answer

Recognition of the Shine-Dalgarno sequence

Question 17

Which of the following best describes the function of the trp operon in E. coli?

Accepted Answer

It is a repressible operon that controls tryptophan biosynthesis

Question 18

Which of the following ribosomal sites is responsible for holding the tRNA carrying the growing polypeptide chain during translation?

Accepted Answer

P site

Question 19

A scientist observes a bacterium dividing by snapping division. Which genus is most likely involved?

Accepted Answer

Corynebacterium

Question 20

Which of the following statements about actinobacteria is correct?

Accepted Answer

They produce geosmin, contributing to the smell of soil

Microbiology Study Guide: DNA Replication, Gene Regulation, Antimicrobial Agents, and Prokaryotic Cell Biology

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