Question 1

Which component of the bacterial cell wall is primarily responsible for its structural strength and is targeted by antibiotics such as penicillin?

Accepted Answer

Peptidoglycan

Question 2

A Gram-positive bacterium is exposed to lysozyme. What is the most likely biochemical effect on its cell wall?

Accepted Answer

Lysozyme hydrolyzes the MurNAc–GlcNAc bond in peptidoglycan

Question 3

Which bacterial structure is most directly involved in horizontal gene transfer via conjugation?

Accepted Answer

Pilus

Question 4

What is the main difference in peptidoglycan cross-linking between Gram-positive and Gram-negative bacteria?

Accepted Answer

Gram-positive bacteria use pentaglycine bridges, Gram-negative use direct cross-links

Question 5

A bacterium is observed to have a single circular chromosome and several small circular DNA molecules carrying antibiotic resistance genes. What are these small DNA molecules called?

Accepted Answer

Plasmids

Question 6

Which of the following equations best describes the relationship between surface area (SA) and volume (V) for a spherical bacterium (coccus) with diameter $$d$$?

Accepted Answer

$$SA = \pi d^2$, V$$ = \frac{\pi $$d^3$$}{6}$$

Question 7

During peptidoglycan synthesis, which enzyme is responsible for flipping Lipid II from the cytoplasmic side to the extracellular side of the membrane?

Accepted Answer

MurJ

Question 8

Which bacterial arrangement is described as cube-like groups of eight cocci?

Accepted Answer

Packets

Question 9

A patient is infected with a bacterium that forms endospores. Which genera are most likely responsible for the infection?

Accepted Answer

Bacillus and Clostridium

Question 10

Which process allows bacteria to acquire new DNA from their environment, rather than from another cell or a virus?

Accepted Answer

Transformation

Question 11

What is the primary function of the bacterial capsule?

Accepted Answer

Protection from immune cells

Question 12

Which of the following best describes the composition of bacterial peptidoglycan?

Accepted Answer

N-acetylglucosamine, N-acetylmuramic acid, and peptide chains

Question 13

A Gram-negative bacterium is more resistant to antibiotics that target peptidoglycan. Which structural feature contributes most to this resistance?

Accepted Answer

Presence of an outer membrane

Question 14

Which bacterial shape is described as a long, flexible corkscrew and moves by twisting?

Accepted Answer

Spirochete

Question 15

What is the main function of bacterial ribosomes?

Accepted Answer

Protein synthesis

Question 16

Which equation best represents the relationship between surface area (SA) and volume (V) for a rod-shaped bacterium (bacillus) with diameter $$d$$ and length $$l$$?

Accepted Answer

$$SA = \pi d l + 2 \pi \frac{d^2$}{4}$$, $$V = \pi \frac{d^2$}{4} l$$

Question 17

Which of the following is NOT a mechanism of horizontal gene transfer in bacteria?

Accepted Answer

Binary fission

Question 18

Which enzyme complex is responsible for polymerizing glycan strands during peptidoglycan synthesis?

Accepted Answer

GT51 polymerase (aPBP complex)

Question 19

A bacterium with a high surface area to volume ratio is likely to:

Accepted Answer

Be more efficient at exchanging materials with its environment

Question 20

Which bacterial cell wall component is absent in Archaea, but present in Bacteria?

Accepted Answer

Peptidoglycan

Bacterial Cell Structure and Cell Wall Infection Science: Study Notes

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