Question 1

Which of the following is a major function of the cytoplasmic membrane in microbial cells?

Accepted Answer

Selective permeability

Question 2

What is the structural difference between the phospholipids in Bacteria/Eukarya and those in Archaea?

Accepted Answer

Bacteria/Eukarya have ester linkages; Archaea have ether linkages

Question 3

Which equation best represents the accumulation of solutes against a concentration gradient by transport proteins?

Accepted Answer

$$ \Delta G = RT \ln \left( \frac{[C]_{in}}{[C]_{out}} \right) $$

Question 4

Which of the following is NOT a component of the Gram-negative bacterial cell envelope?

Accepted Answer

Thick peptidoglycan layer

Question 5

A patient is infected with a bacterium that is resistant to lysozyme and penicillin. Which cell wall structure is most likely present?

Accepted Answer

Pseudomurein

Question 6

Which of the following statements about S-layers is TRUE?

Accepted Answer

S-layers provide strength and protection from lysis

Question 7

Which transport system involves chemical modification of the transported substance?

Accepted Answer

Group translocation

Question 8

Which of the following is a toxic component of the Gram-negative outer membrane?

Accepted Answer

Lipid A

Question 9

Which of the following best describes the function of porins in the outer membrane?

Accepted Answer

Form channels for entrance and exit of solutes

Question 10

Which of the following cell envelope structures is found in Mycoplasmas?

Accepted Answer

Tough cytoplasmic membrane containing sterols

Question 11

Which of the following is a function of membrane proteins in the cytoplasmic membrane?

Accepted Answer

Energy metabolism

Question 12

Which of the following statements about Gram-positive cell walls is correct?

Accepted Answer

They have a thick peptidoglycan layer stabilized by peptide cross-links

Question 13

Which of the following is destroyed by lysozyme in human secretions?

Accepted Answer

Peptidoglycan

Question 14

Which of the following is true about the proton motive force?

Accepted Answer

It is generated by the cytoplasmic membrane and used for energy conservation

Question 15

Which of the following is a correct description of the hydrophobic and hydrophilic regions in the phospholipid bilayer?

Accepted Answer

Hydrophilic head groups face the external environment or cytoplasm

Question 16

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

Accepted Answer

DNA replication

Question 17

Which of the following best explains why penicillin is effective against Gram-positive bacteria?

Accepted Answer

It blocks the formation of peptide cross-links in peptidoglycan

Question 18

Which of the following is true about the periplasmic space in Gram-negative bacteria?

Accepted Answer

It houses many extracellular proteins

Question 19

Which of the following is a distinguishing feature of archaeal cell walls compared to bacterial cell walls?

Accepted Answer

Presence of S-layer as the main structural component

Question 20

A researcher isolates a microorganism with a cell envelope consisting only of a tough cytoplasmic membrane containing sterols. Which organism is most likely being studied?

Accepted Answer

Mycoplasma

Microbial Cell Structure and Function: The Cell Envelope

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