Question 1

Which repeating sugar units are found in the peptidoglycan structure of bacterial cell walls?

Accepted Answer

N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)

Question 2

What type of glycosidic linkage connects the repeating units in peptidoglycan?

Accepted Answer

$$\beta-1$$,4 linkage

Question 3

Which molecule provides the cross-links between peptidoglycan polysaccharide chains?

Accepted Answer

Protein (peptide)

Question 4

What is the primary function of peptidoglycan in bacteria?

Accepted Answer

Structural support

Question 5

Which statement best describes the structure of the Gram-negative bacterial cell wall?

Accepted Answer

A thin layer of peptidoglycan with an outer membrane on top

Question 6

Why do Gram-positive bacteria retain the crystal violet stain during Gram staining?

Accepted Answer

They have a thick peptidoglycan layer that traps the stain

Question 7

Which of the following is NOT a characteristic of peptidoglycan?

Accepted Answer

It is branched

Question 8

In a clinical setting, why is it important to distinguish between Gram-positive and Gram-negative bacteria?

Accepted Answer

Gram-negative bacteria have an outer membrane that can affect antibiotic susceptibility

Question 9

Which enzyme is responsible for cleaving the $$\beta-1$$,4 glycosidic bond in peptidoglycan?

Accepted Answer

Lysozyme

Question 10

A mutation prevents the formation of peptide cross-links in a bacterium’s peptidoglycan. What is the most likely consequence?

Accepted Answer

Loss of structural integrity and cell lysis

Question 11

Which of the following best explains why Gram-negative bacteria do not retain the crystal violet stain?

Accepted Answer

Their thin peptidoglycan layer is unable to trap the stain after alcohol wash

Question 12

Which of the following is a correct description of the peptidoglycan structure?

Accepted Answer

Alternating units of N-acetylglucosamine and N-acetylmuramic acid linked by $$\beta-1$$,4 bonds

Question 13

Which of the following antibiotics targets the synthesis of peptidoglycan?

Accepted Answer

Penicillin

Question 14

If a bacterium is Gram-positive, which of the following must be true?

Accepted Answer

It has a thick peptidoglycan layer

Question 15

Which of the following best describes the branching in peptidoglycan?

Accepted Answer

Peptidoglycan is not branched

Question 16

Which of the following is a real-world consequence of peptidoglycan disruption in bacteria?

Accepted Answer

Bacteria lose their shape and may lyse

Question 17

Which of the following statements about the outer membrane in Gram-negative bacteria is correct?

Accepted Answer

It is located above the peptidoglycan layer

Question 18

Which of the following best describes the role of peptide cross-links in peptidoglycan?

Accepted Answer

They provide structural strength and rigidity

Question 19

Which of the following is a direct consequence of the $$\beta-1$$,4 glycosidic linkage in peptidoglycan?

Accepted Answer

Susceptibility to lysozyme

Question 20

A patient is infected with a bacterium that is resistant to penicillin. Which structural feature of the cell wall might explain this resistance?

Accepted Answer

Altered peptide cross-links in peptidoglycan

Peptidoglycan Structure and Function in Bacterial Cell Walls

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