Lecture 2.4

Question 1

List some differences between gram + and gram - bacteria

Answer 1

1. Gram+ have a lot more peptidoglycan outside the cell with no outer membrane, contains lipoteichoic and teichoic acids
2. Gram- have an outer membrane with LPS

Question 2

What part of the bacteria does not induce an inflammatory response?

Answer 2

Capsule (usually polysaccarides)

Question 3

Where does peptidoglycan crosslinking occur and what drug splits the crosslinking

Answer 3

outside the cell/penicillin

Question 4

Describe the construction of the peptidoglycan layer in bacteria

Answer 4

UDP-NAM binds to 5 linked peptides (last two being l and d alanine, which is inhibited by cycloserine)–> UDP-NAM binds to bactophenol which has one phosphate itself–>bactophenol-PP-NAM reacts with UDP-NAG–>bactophenol-pp-NAM-NAG is carried to the outside of the membrane–> NAM-NAG crosslink with existing peptidoglycan (inhibited by vancomycin)–> Bactophenol loses one phosphate and goes back inside the membrane

Question 5

What are the components of an LPS

Answer 5

1. O side chain (variable)
2. Core polysaccharide
3. Lipid A (endotoxin, causes inflammation)

Question 6

What are the unique structures on the outside of a Gram + cell and where are they anchored

Answer 6

1. Teichoic acids anchored to peptidoglycan
2. Lipoteichoic acid anchored to cell membrane
   (Both cause inflammation)

Question 7

How can polysaccharide bacterial capsules be visualized

Answer 7

Quellung reaction (swelling)

Question 8

These bacterial structures play a role in adherence to mucosal surfaces and can be involved with conjugation, usually cover gram- bacteria

Answer 8

Pili

Question 9

What are the three classification of bacteria according to their flagella (flagella are immunogenic)

Answer 9

Polar flagella, peritrichous, monotrichous

Question 10

What powers flagella movement in bacteria?

Answer 10

H+ gradient (256 H+ must move into the cell membrane from the periplasmic space for one turn)

Question 11

In what stage of bacterial growth are most bacteria in?

Answer 11

Stationary

Question 12

At what point in the spore growth cycle confers irreversibility?

Answer 12

Cortex formation

Question 13

What are the four chemicals that bacteria require in order to survive?

Answer 13

Phosphate, sulfur, ammonia (NH3), a carbon source

Question 14

What do aerobic bacteria have that prevents harmful effects of oxidation?

Answer 14

SOD, catalase

Question 15

What do aerotolerant bacteria have that make them semi able to resist the effects of oxidation?

Answer 15

SOD

Question 16

What element is essential for the life of the bacteria?

Answer 16

Iron (Fe2+ confers energy, Fe3+ acts as a terminal electron acceptor)

Question 17

What do some bacteria have that overcomes the fact that humans have very little circulating iron (due to binding to ferritin, transferritin, hemin, lactoferrin)

Answer 17

Siderophores, high affinity for iron

Question 18

How do bacteria survive without oxygen?

Answer 18

Embden meyerhof pathway (EMP), basically the glycolytic pathway, produces two ATP (EDP only produces one ATP because only on pyruvate is made)