Lecture 3- Peptidoglycan Synthesis And Eukaryotic Cell Structure

Question 1

How does the antibiotic vancomycin inhibit peptidoglycan synthesis?

Answer 1

It blocks the formation of D-Ala-D-Ala

Question 2

How does the antibiotic penicillin interfere with peptidoglycan synthesis?

Answer 2

It inhibits the transpeptidation reaction

Question 3

How does the antibiotic bacitracin inhibit peptidoglycan synthesis?

Answer 3

It blocks the dephosphorylation of bactoprenol pyrophosphate

Question 4

Gram-positive bacteria stain what color?

Answer 4

Purple

Question 5

Gram-negative bacteria stain what color?

Answer 5

Pink

Question 6

When doing a gram stain what is the primary stain used?

Answer 6

Crystal violet (in combination with iodine)

Question 7

What is the purpose of iodine being added to the primary stain?

Answer 7

It acts as a mordant to enhance the crystal violet staining

Question 8

When doing a gram stain what would you use for a counter stain?

Answer 8

Safranin

Question 9

Name three characteristics of a gram-positive cell wall.

Answer 9

• 2-ring basal body
• It is disrupted by lysozyme
• it is penicillin sensitive

Question 10

Name three characteristics of a gram-negative cell wall.

Answer 10

• 4-ring basal body
• Endotoxins
• It is tetracycline sensitive

Question 11

What does acid fast staining refer to?

Answer 11

Acid-fast stain is a differential stain used to identify acid-fast organisms such as members of the genus Mycobacterium. Acid-fast organisms are characterized by wax-like, nearly impermeable cell walls; they contain mycolic acid and large amounts of fatty acids, waxes, and complex.

Question 12

Acid-fast cells resist ______________ with acid alcohol?

Answer 12

Decolorization

Question 13

The basis for acid-fast staining is a waxy cell wall composed of __________ __________?

Answer 13

Mycolic acids

Question 14

Acid-fast staining methods use what lipid soluble stain?

Answer 14

Carbolfuchsin

Question 15

T/F: Acid fast cells often abnormal Gram stain results?

Answer 15

True

Question 16

Why is acid fast staining of importance?

Answer 16

It is important for identifying bacteria in the the genus Mycobacterium, which can be pathogenic, such as M. leprae and M. tuberculosis

It is also important because it can be used to identify opportunistic pathogens of the actinomycete genus Nocardia and oocysts of cocci dial parasites, such as cryptosporidium and Isospora

Question 17

Acid-fast bacteria stain what color?

Answer 17

Red

Question 18

Non-acid-fast bacteria stain what color?

Answer 18

Blue

Question 19

These organisms lack cell walls and contain sterols in their plasma membrane?

Answer 19

Mycoplasmas

Question 20

These organisms either lack a cell wall OR contain a wall made of pseudomurein

Answer 20

Archaea

Question 21

How does the antibiotic Vancomycin interfere with peptidoglycan synthesis?

Answer 21

It inhibits transpeptidation by binding to D-Ala-D-Ala