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Veterinary Microbiology > Microbial Growth > Flashcards

Microbial Growth Flashcards

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Biology 101 flashcards
1
Q

what is the bacterial cell cycle?

A

the sequence of events from the formation of a new cell through the next cell division

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2
Q

how do bacteria replicate?

A

through binary fission

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3
Q

what are the 3 phases of the bacterial cell cycle?

A
  1. period of growth after the cell is born
  2. chromosome replication and partitioning
  3. cytokenesis
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4
Q

what are the 5 stages of binary fission?

A
  1. cell at early phase of life cycle
  2. chromosome replication; prep for division by enlarging cell wall, plasma membrane, and overall volume
  3. septum grows inward as chromosomes move toward opposite ends of cell; distribute cytoplasmic components
  4. septum synthesized completely through cell center, creating two separate cell chambers
  5. division
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5
Q

describe most bacterial chromosomes

A

singular, circular chromosome

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6
Q

how many replication origins do bacteria have?

A

just one

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7
Q

what is the single origin of replication in a bacterial cell?

A

site at which replication begins

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8
Q

what is the terminus in bacterial cells?

A

site at which replication is terminated, located opposite of the origin

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9
Q

what is the replisome of bacterial cells?

A

group of proteins needed for DNA synthesis

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10
Q

in what direction does DNA synthesis proceed?

A

in BOTH directions from the origin of replication

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11
Q

where do the origins of replication move to in microbial replication?

A

opposite ends of cell

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12
Q

what is septation also known as?

A

cytokinesis

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13
Q

when does septation begin?

A

when the z ring forms

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14
Q

describe septation in terms of the Z ring and MinCD

A

MinCD is a protein that oscillates back and forth across the bacteral cell, and keep the Z ring from forming until the cell is long enough that it takes too much time to go from one end of the cell to another, thus allowing the Z ring to form one the cell is ready for septation

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15
Q

what is septation?

A

formation of the cross wall between two daughter cells

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16
Q

what are the 4 steps of septation?

A
  1. selection of site for septum formation
  2. assembly of Z ring
  3. assembly of cell-wall synthesizing machinery
  4. constriction of cell and septum formation
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17
Q

what protein is the Z ring composed of?

A

FtsZ

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18
Q

what part of the bacterial life cycle do a lot of antibiotics target?

A

cell growth and division

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19
Q

what is important to take away from the super complex process of septation?

A

that you can attack steps along the way to treat infection

20
Q

when does Z ring formation occur?

A

after replication of genetic material

21
Q

is FtsZ the only protein involved in Z ring formation?

A

no there are others involved, but don’t worry about it

22
Q

what must be synthesized as cells divide?

A

peptidoglycan!!

23
Q

what is cellular growth?

A

increase in cellular constituents

24
Q

what 2 things could cellular growth result in?

A
  1. increase in cell number

2. increase in cell size

25
Q

what does cellular growth refer to?

A

population growth rather than growth of individual cells

26
Q

when is the microbial growth curve observed?

A

when microorganisms are cultivated in batch culture

27
Q

how is the microbial growth curve plotted?

A

as the logarithm of cell number versus time

28
Q

what are the 5 distinct phases of the microbial growth curve?

A
  1. lag phase
  2. log phase
  3. stationary phase
  4. death phase
  5. long-term stationary phase
29
Q

what happens in the lag phase of microbial growth curve?

A

cell is synthesizing new components

30
Q

give two reasons why the cell would need to synthesize new components in the lag phase of the microbial growth curve

A
  1. to replenish spent material

2. to adapt to new medium or other conditions

31
Q

how long is the lag phase?

A

varies in length, can be very short or even absent

32
Q

what is the log phase of the microbial growth curve also called?

A

exponential phase

33
Q

describe rate of growth in the log phase of the microbial growth curve

A

constant and maxmal

34
Q

describe the microbial population in the log phase of the microbial growth curve

A

uniform in terms of chemical and physical properties

35
Q

describe the stationary phase of the microbial growth curve

A

closed system population growth eventually ceases; total number of viable cells remains constant

36
Q

what cancels out during the stationary phase of the microbial growth curve?

A

cell death = cell growth

37
Q

what may happen to the population in the stationary phase of the microbial growth curve?

A

population may cease to divide, but remain metabolically active

38
Q

what are the 4 possible reasons for the stationary phase of the microbial growth curve?

A
  1. nutrient limitation
  2. limited oxygen availability
  3. toxic waste accumulation
  4. critical population density reached
39
Q

what is the stationary phase of the microbial growth curve also called?

A

holding pattern/plateau

40
Q

what is the death phase of the microbial growth curve?

A

when the number of viable cells declines exponentially, with cells dying at a constant rate

41
Q

what happens during the death phase of the microbial growth curve in terms of the environment?

A

detrimental environmental changes cause irreparable harm to the cells

42
Q

list and describe 2 hypotheses for why the death phase occurs

A
  1. cells are viable but not culturable (VBNC): cells alive, but dormant, capable of new growth when conditions are right
  2. programmed cell death: fraction of the population genetically programmed to die (commit suicide)
43
Q

what happens in the long-term stationary phase of the microbial growth curve?

A

bacterial population continually evolves

44
Q

what is the long-term stationary phase of the microbial growth curve marked by?

A

successive waves of genetically distinct variants

45
Q

what occurs during the long-term stationary phase of the microbial growth curve?

A

natural selection

Veterinary Microbiology (11 decks)

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