7. Prokaryotic Cell Structures & Functions

Which is (are) true concerning the cell wall of prokaryotes?

Peptidoglycan is made up of:

The NAG and NAM molecules of peptidoglycan are connected by a:

The glycan chains of adjacent peptidoglycan molecules are connected by:

The Gram stain works because of differences in the ________ of bacteria.

Answer the following questions using the diagrams provided, which represent cross sections of bacterial cell walls.

a. Which diagram represents a gram-positive bacterium? How can you tell? <IMAGE>

b. Explain how the Gram stain works to distinguish these two types of cell walls.

c. Why does penicillin have no effect on most gram-negative cells?

d. How do essential molecules enter cells through each wall?

e. Which cell wall is toxic to humans?

If you Gram-stained the bacteria that live in the human intestine, you would expect to find mostly

a. gram-positive cocci.

b. gram-negative rods.

c. gram-positive, endospore-forming rods.

d. gram-negative, nitrogen-fixing bacteria.

e. all of the above.

Bacteria cell walls tend to contain:

a. Peptidoglycan.

b. Lipid bilayers.

c. Cholesterol.

d. Pseudomurein.

e. Flagellin.

Which of the following statements is true?

a. The cell walls of bacteria are composed of peptidoglycan.

b. Peptidoglycan is a fatty acid.

c. Gram-positive bacterial walls have a relatively thin layer of peptidoglycan anchored to the cytoplasmic membrane by teichoic acids.

d. Peptidoglycan is found mainly in the cell walls of fungi, algae, and plants.

For each of the following statements that is true, write “true” in the blank. For each statement that is false, write the word(s) that should be substituted for the underlined word(s) to make the statement correct.

__________ Chlamydias have peptidoglycan cell walls.

The presence of mycolic acid in the cell wall characterizes __________ .

a. Corynebacterium

b. Listeria

c. Nocardia

d. Mycobacterium

The peptidoglycan molecule is responsible for the: