Bac metabolism Lec 4. 4

Question 1

What is pH? Why do I care…?

Answer 1

pH is the absolute value of the exponent of the molar concentration of hydrogen ion in solution. (0-6=acid; 8-14=alkaline) I care because:
1) acidity or alkalinity of an environment
can greatly affect microbial growth
2) Microbes DIFFER in the pH ranges they tolerate

Question 2

most human microbes tolerate what pH?

Answer 2

pH 5-8

Question 3

What is optimum pH? Human blood is what pH?

Answer 3

• optimum is pH 7

* human blood pH 7.35

Question 4

acidophiles love____ envirnment? Ex?

Answer 4

acidic environment

*lactobacilli in oral cavity grow best at pH of 5.5 during glucose load

Question 5

Dental plaque is a localized _____; it’s pH is important for caries development

Answer 5

biofilm

Question 6

Bacteria such as Streptococcus mutans, which are often part of the plaque, have the capacity to produce _______ from sucrose or glucose

Answer 6

lactic acid

Question 7

production of acid in the plaque will cause?

Answer 7

localized demineralization of teeth, in

other words a carious lesion

Question 8

Stephan’s curve demonstrates the ability of oral bacteria to produce?

Answer 8

acid in presence of a glucose

Question 9

What could change the severity of the

Stephan’s curve? (4 specific things)

Answer 9

 Whether or not lactic acid producing
bacteria are present
 How well the bacteria adhere to the
tooth/Can the bacteria produce adherence factors
 Whether or not we produce low or high
concentrations of antibodies to the adherence factors
 The buffering capacity of saliva/the
amount of saliva

Question 10

Xerophiles are microbes that grow in?

Answer 10

very dry environment

Question 11

Explain Xerophiles reaction to water

Answer 11

Water is bad for survival when its amount increases in the environment. To counteract this situation, organisms produce or accumulate intracellular ‘compatible solutes’ that maintain the cell in positive water balance.

Question 12

halophiles grow best in?

Answer 12

low or reduced water

Question 13

extreme halophiles require high levels of what to grow?

Answer 13

salts

Question 14

halotolerant organisms can tolerate?

Answer 14

some reduction in the water activity in their environment, but generally grow best in the absence of the added solute

Question 15

what is generation time?

Answer 15

time for one generation through binary fission

Question 16

binary fission steps?

Answer 16

1) DNA replication
2) cell elongation
3) septum formation
4) completion of septum with formation of distint walls
5) cell separation

Question 17

What protein is key to regulating cell division and chromosome replication? what do they form?

Answer 17

Fts proteins

* Fts proteins interact to form a division apparatus in the cell called the divisome

Question 18

protein FtsZ is composed of? what does it do?

Answer 18

composed of 10,000 polymerized molecules at the divisome

*defines the division plane in prokaryotes and Mre proteins help define cell shape

Question 19

what is FtsI?

Answer 19

a penicillin binding protein required for penicillin action

Question 20

what is FtsA?

Answer 20

an anchor protein

Question 21

Cell wall synthesis is required when the?

Answer 21

bacterial cell is dividing

Question 22

Cell wall synthesis is dependent upon ______ enzyme. Does what?

Answer 22

autolysins-enzymes

*which degrade existing peptidoglycan

Question 23

Mre protein does what?

Answer 23

governs the shape of the organism (spiral or rod)

Question 24

When is the intensity of FtsZ stain is the greatest?

Answer 24

when the nucleiod/DNA is separating at the septum during divisome

Question 25

why is the bacteria so susceptible during cell division?

Answer 25

Bc at the divisome, they have to dissolve the peptidoglycan with endogenous autolysins **THIS is necessary for the bacteria to grow (so exogenous enzymes can use this as a weapon)

Question 26

autolysins are analogous to our?

Answer 26

lysozymes; break beta 1,4 bond of peptidoglycan