Bacterial Structures

Question 1

Name 3 commonly known bacterial species which are spirochetes in shape.

Answer 1

Borrelia, Treponema, Leptospira

Question 2

Which is the smallest bacteria?

Answer 2

Mycoplasma (they don’t have cell walls but contain STEROLS rather)

Question 3

Lysozymes are enzymes found in the saliva capable of killing bacteria by what mechanism?

Answer 3

Cleaving the BETA 1-4 LINKAGE in bacterial cell wall

Question 4

These are proteins in the outer membrane of gram negative bacteria that act as channel for essential substances such as sugars, amino acids and where some antimicrobial drugs like beta-lactams passes through.

Answer 4

PORINS

Question 5

Which substance is UNIQUE to the cellwall of GRAM NEGATIVE bacteria?

Answer 5

LPS (Lipopolysaccharide aka ENDOTOXIN)

Question 6

ALL Gram (+) bacteria have no ENDOTOXIN EXCEPT?

Answer 6

Listeria moncytogenes

Question 7

These substance confer elasticity, porosity and tensile strength to the cell wall and is unique to Gram (+) bacteria.

Answer 7

Teichoic Acid

Question 8

What are the 4 STEPS in the GRAM STAINING procedure?

Answer 8

Priamary Stain (Crystal Violet) Mordant (Iodine) Decolorizer (Acetone/Alcohol) Counterstain (Safranin)

Question 9

What are the important components of ENDOTOXIN?

Answer 9

Lipid A = Causes almost all the toxicity ; O antigen = stimulates IL-1 and TNF-alpha production

Question 10

Which are the two OBLIGATE INTRACELLULAR bacteria?

Answer 10

Rickettsiae; Chalmydia

Question 11

What is the stain used for Legionella?

Answer 11

Silver Stain

Question 12

Which stainingtechnique is usedto identifychromosomal materialorDNAin cell specimens?

Answer 12

Feulgen Stain

Question 13

Beta-lactamases which are necessary for penicillin resistance in some gram negative bacteria are found in which portion of the bacteria?

Answer 13

Periplasm

Question 14

The capsule of almost all bacteria are composed of POLYSACCHARIDE except?

Answer 14

Bacillus anthracis (composed of polypedtide of D-Glutamate)

Question 15

Which substance confers heat resistance to SPORES?

Answer 15

dipicolinic acid

Question 16

Give two bacterial species which produce spore.

Answer 16

Bacillus and Clostridium

Question 17

Most bacteria have LPS in their cell wall as the endotoxin. Which 2 bacteria have LOS instead?

Answer 17

Neisseria, Haemophilus

Question 18

Which bacteria are not seen in Gram Staining? What are the alternative techniques used?

Answer 18

Mycobacteria (Acid fast); Spirochetres (Dark field microscopy); Legionella (Silver Stain); Rickettsiae (Giemsa/tissue stain); Chlamydia (inclusion bodies)

Question 19

Whats are the ribosomal subunits of bacteria?

Answer 19

30s (acted upon by Tetracycline and Aminoglycoside); 50s (Lincosamide, Chloramphenicol, Macrolides)