Bacterial Physiology Flashcards

1
Q

binary fission

A

the way which bacteria reproduce

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2
Q

Does bacteria grow linearly or exponentially?

A

exponential growth

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3
Q

mass of one bacterial cell

A
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4
Q

generation (doubling) time

A

the amount of time required for one bacterium to become two

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5
Q

Typical generation time for medically important bacteria under ideal conditions?

A

20 minutes

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6
Q

Are Mycobacterium notoriously fast or slow replicators?

A

slow - 20 hours to 20 days!

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7
Q

Generation time for Clostridium perfringens?

A

~6 minutes

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8
Q

4 Parts of the Sigmoid Growth Curve

A
  1. Lag phase
  2. Logarithmic phase
  3. Stationary phase
  4. Death/decline phase
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9
Q

Lag phase

A

time for bacteria to adjust to a new environment; maturing but not yet able to divide; synthesis of molecules does occur

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10
Q

Logarithmic phase

A

period characterized by cell doubling (exponential)

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11
Q

Stationary phase

A

growth and death rate are equal here
due to depletion of a necessary nutrient or formation of inhibitory product

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12
Q

Death/Decline phase

A

bacteria die due to too many toxins, lack of nutrients, temperature out of survival range, host immune response, etc.

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13
Q

One (1) Colony on an Agar Plate is a result of how many cell divisions?

A

20-30 cell divisions of a single cell - can be more than a billion bacteria!

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14
Q

Typical optimal pH requirements?

A

between 7.2 and 7.6

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15
Q

Typical optimal temperature requirement for growth of most pathogenic bacteria?

A

37 C

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16
Q

Methods used to control bacterial growth?

A

refrigeration and sterilization by heat

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17
Q

Will heat kill spores?

A

no guarantee, they’re hardy little buggers

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18
Q

psychrophile

A

capable of reproduction at low temperature (10 C)

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19
Q

mesophile

A

grows best in moderate temperature (37 C, majority of microbes)

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20
Q

thermophile

A

grows best at higher than normal temperature (65 C)

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21
Q

hyperthermophile

A

very high thermostability (over 90 C)

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22
Q

heterotroph

A

must ingest biomass to grow, and that biomass can be converted to the essential nutrients of carbon, nitrogen, cofactors, etc.

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23
Q

cyanobacteria

A

able to carry out photosynthesis and can sustain themselves

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24
Q

prototrophs

A

WILD-TYPE bacteria that can synthesize all compounds needed for growth from simple ingredients

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25
Q

auxotrophs

A

mutant bacteria that are unable to synthesize a particular compound (AA, nucleotide, etc) required for its growth

26
Q

fastidious organisms

A

organisms with a complex nutritional requirement and will only grow if cofactors are provided in their diet

27
Q

Minimum nutritional requirements for bacterial replication (4)

A
  1. Water
  2. Carbon
  3. Nitrogen
  4. inorganic salts
28
Q

Water makes up ___% total weight of bacterial cells.

A

80%

29
Q

Components of a Bacterial Cell

A

water, proteins, polysaccharides, lipids, nucleic acids, peptidoglycan, and other low molecular weight compounds

30
Q

Two Types of Growth Factors

A
  1. Essential
  2. Accessory
31
Q

iron

A

an essential growth factor for bacteriar

32
Q

growth factor

A

certain compound in minute quantities for bacterial growth

33
Q

obligate (strict) aerobes

A

require oxygen

34
Q

microaerophiles

A

need oxygen, but poisoned if the levels of oxygen are too high

35
Q

facultative aerobes/anaerobes

A

can switch between energy metabolism pathways depending on the presence or lack of oxygen

36
Q

aerotolerant anaerobes

A

can only generate energy via anaerobic metabolism but can tolerate the presence of oxygen

37
Q

obligate anaerobes

A

oxygen is TOXIC (will kill or inhibit their growth)

38
Q

What type of growth is occurring in each of the following test tubes (choices listed)?

aerobic, facultative, aerotolerant, microaerophilic, anaerobic

A
39
Q

3 Different Methods of Energy Metabolism

A
  1. Aerobic Respiration
  2. Anaerobic Respiration
  3. Fermentation
40
Q

Is any additional ATP made in the fermentation pathway?

A

no - only has the ATP from glycolysis

41
Q

Which method(s) of energy metabolism do not require oxygen?

A

anaerobic respiration and fermentation

42
Q

2 Different Fermentation Pathways

A
  1. Homolactic acid
  2. Alcoholic
43
Q

What is NEVER the final electron receptor in anaerobic respiration?

A

oxygen, of course!

44
Q

4 Subpathways of Cellular Respiration

A
  1. Glycolysis
  2. synthesis of Acetyl-CoA
  3. Krebs Cycle
  4. Electron transport chain
45
Q

Most energy efficient pathway?

A

aerobic respiration

46
Q

ATP produced by Aerobic Respiration

A

38

47
Q

ATP produced by Anaerobic Respiration

A

36 or less (usually less)

48
Q

ATP produced by Fermentation

A

2

49
Q

What enzymes do obligate anaerobes lack (in general)?

A

those which detoxify oxygen species

(superoxide dismutases, catalases, peroxidases)

50
Q

reducing agents

A

components that can be added to sample to allow culture of anaerobes so they may grow in low oxygen conditions

51
Q

Mitsubishi box

A

name brand anaerobic chamber of sorts, does not require reducing agents?

52
Q

sulfhydryl group

A

commonly used reducing agent to take the oxygen away

53
Q

Functions of Reducing Agents in the Medium

A
  1. Absorb oxygen
  2. Reduce H2O2
54
Q

Primary factor in the growth of anaerobes?

A

Redox potential! (Eh)

55
Q

Effect of Oxygen on Redox Potential

A

increase in oxygen increases the redox potential, therefore preventing the growth of anaerobes

56
Q

Reduction

A

gain of electrons

57
Q

Oxidation

A

loss of electrons

58
Q

Nernst Equation

A

just to look at, not to memorize

59
Q

What happens as Eh falls below 150 mvolts?

A

lower redox potential = good reducing environment = promotes growth of anaerobes

60
Q

Eh of Normal Healthy Tissue

A

~ +150 mvolts

61
Q

Conditions which can lower Eh values (4)

A

-Loss of vascular supply to tissue
-Trauma, foreign bodies, pressure from casts
-Acid production by aerobes or facultative
anaerobes
-Tissue necrosis from trauma, infection, or
surgical manipulation

62
Q

Are most anaerobic infections exogenously or endogenously acquired?

A

endogenously - meaning these are related to factors compromising the host like trauma, antibiotic therapy, or underlying illness