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Micro : Unit 1 > Chapter 7: Bacterial and Archaeal Growth > Flashcards

Chapter 7: Bacterial and Archaeal Growth Flashcards

1
Q

What’s the process in which most bacteria and archaea reproduce and what are the steps of this process?

A

Binary fission - reproduction of a cell by division into two approximately equal parts the binary fission of protozoans

  1. Cell elongation
    (enlargement) – cell wall,
    plasma membrane, and
    volume → increase
  2. Chromosome is
    replicated and separated
  3. Cross wall (septum) is
    formed, which splits cell
    into → two daughter
    cells
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2
Q

Bacterial Cell Cycle

A

• Cell cycle is sequence
of events from the
formation of a new cell
through the → next
cell division

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3
Q

What are the three phases of the cell cycle?

A
  1. Growth period after cell
    division
    • Similar to G1
  2. Chromosome replicates
    and partitions
    • Similar to S phase and mitosis
  3. Septum forms and two separate daughter cells are created
    • Cytokinesis
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4
Q

Most bacterial have one ____
chromosome

A

circular

• Single origin of replication – site
at which replication → begins

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5
Q

origin of replication

A

site at which replication → begins

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6
Q

Terminus

A

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

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7
Q

Replisome

A

group of proteins needed for → DNA synthesis

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8
Q

DNA replication proceeds…

A

In both directions (bidirectionally) from the origin

• Origins move to opposite ends of the cell

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9
Q

There are three parts to the partitioning system:

A

The ParA, Par B, and ParC.

-ParA and ParB protein act like the eukaryotic →
centromere

-ParS are regions on the chromosome near the origin of replication

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10
Q

ParB then ParA proteins bind onto the ParS sites

A

• Creates the → partition complex
• ParB and ParA pull the chromosomes by the ParS sites to the opposite poles of the cell

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11
Q

Cytokinesis

A

occur after cell
division when two daughter
cells are created

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12
Q

Septation

A

formation of
cross walls between
daughter cells

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13
Q

Cytokinesis

A

• Selection of site for septum formation
• Assembly of Z ring (composed of protein
FtsZ)
• Assembly of cell wall synthesizing
machinery
• Constriction of cell and septum formation

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14
Q

The Growth Curve

A

• Observed when microorganisms are grown in → batch
culture
Closed culture with a single → batch of medium
• Usually plotted as logarithm of → cell number vs. time
• Has five distinct phases

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15
Q

Lag phase

A

time after microbes have been introduced to
fresh medium
• There is no increase in → cell numbers
• During this time cells are either too old or low on ATP and other factors necessary for reproduction
• New factors have to be made to reproduce and cells
need time to recover from their transfer

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16
Q

Exponential (log) phase

A

microbes are growing and
dividing at the → maximum rate possible
• Based on genetics, the medium used, and
environmental conditions

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17
Q

Stationary phase

A

common in a closed batch system, cell
population will eventually slows and the growth curve is →horizontal
• Population numbers depend on available nutrients and the type of→ microbe

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18
Q

Possible reasons for stationary phase:

A

• Nutrient limitation
• Limited oxygen availability
• Toxic waste accumulation
• Critical population density reached

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19
Q

Death phase

A

the number of viable cells declines because
of cells dying at a constant rate
• Debate as to why this occurs
• Nutrient deprivation or buildup of waste

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20
Q

Viable but nonculturable (VBNC)

A

cell response to
starving, temporarily unable to grow
• Once conditions improve cells will begin to →grow
again

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21
Q

Programmed cell death

A

part of the microbial population
is genetically programmed to die after growth stops
• Sacrificing themselves to benefit the population

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22
Q

Long-term stationary phase

A

(extended stationary phase)–
after a time of death the population → remains constant
• Microbial population evolves to use nutrients that are
available and tolerate → toxins

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23
Q

Generation (doubling) time

A

Time required for the population to
double in size
• Varies depending on species of
microorganism and environmental
conditions
• Range from 10 minutes for some
bacteria to days for some eukaryotes

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24
Q

Hypotonic solution

A

(lower osmotic concentration)
• Water enters the cell
• Cell swells and may burst (plasmoptysis)

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25
Q

Hypertonic

A

(higher osmotic concentration)
• Water leaves the cell
• Membrane shrinks from cell wall (plasmolysis)

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26
Q

• To reduce osmotic concentration of cytoplasm in
hypotonic solutions:

A

Mechanosensitive (MS) channels in plasma membrane
allow solutes to → leave

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27
Q

To increase their internal osmotic
concentration in hypertonic solutions:

A

• Increase internal solute
concentration with
(Osmoprotectants) compatible
solutes
• Solutes compatible with metabolism
and growth

28
Q

Halophiles

A

require 1.5 % of NaCl or
above

29
Q

Halotolerant

A

can grow in high salt
concentrations but do not require it
(up to 10%)
• Staphylococci

30
Q

Osmotolerant

A

able to grow in a wide
variety of water or osmotic
concentrations

31
Q

Extreme halophiles

A

require salt
concentrations of >10%

Extremely high concentrations of →
potassium
• Cell wall, proteins, and plasma
membrane require high salt to maintain
stability and activity

32
Q

Halophiles and osmophiles use ___________ to
synthesize or obtain molecules from their environment

A

compatible solutes

• Keep the osmotic concentration of the cell isotonic to
the cells habitat
• So the plasma membrane is always firmly pressed
against the → cell wall

33
Q

pH

A

is the measurement of the acidity of a solution
(hydrogen ion (H+) concentration)

34
Q

Acidophiles

A

optimum growth is between pH → 0 to
5.5
• Archaea, fungi, and photosynthetic protists

35
Q

Neutrophiles

A

optimum growth is between pH → 5.5-
8.0
• Most bacteria

36
Q

Alkaliphiles

A

optimum growth is between pH → 8 to 11.5
• All three domains, wide range, marine microbes

37
Q

Most microbes maintain an internal pH at

A

neutral

• Plasma membranes are impermeable to → protons (H+)
• Exchange potassium for protons

38
Q

Acidic tolerance response when external pH is → too low

A

• Pump protons out of the cell (ATPase enzyme)
• Some synthesize acid and heat shock proteins that
protect proteins from → denaturation

39
Q

Many microorganisms change the pH of their habitat by
producing __________

A

acidic or basic→ waste products

40
Q

Can microorganisms regulate their internal
temperature?

A

no

41
Q

Enzymes have optimal temperature at which they function
optimally

A

• High temperatures may inhibit enzyme functioning and
be lethal

42
Q

Organisms exhibit distinct cardinal growth temperatures.

What are cardinal growth temperatures?

A

• Minimal
• Maximal
• Optimal

43
Q

Psychrophiles

A

0C to 20C

44
Q

Psychrotrophs (phychrotolerant)

A

0C to 35C

Arctic or Antarctic habitats • Cause spoilage in
refrigerator temperatures

45
Q

Mesophiles

A

20C to 45C

• Human pathogens

46
Q

Thermophiles

A

45C to 85C

47
Q

Hyperthermophiles

A

85C to 100C
• Composts, haystacks, hot
water lines, and hot
springs

48
Q

Protein structure stabilized by a variety of means

A

• More hydrogen bonds
• Larger amounts of amino acids (proline)
• Chaperones help stabilize and fold proteins

49
Q

Histone-like proteins…..

A

stabilize DNA

50
Q

Membrane stabilized by variety of means

A

• More saturated fatty acids, more branched, and higher
molecular weight lipids
• Increases melting points of membrane lipids

51
Q

Growth in presence of different oxygen concentrations
depends on a microbe’s metabolic processes:

A

• Electron transport chains (ETC)
• Final electron acceptor is → oxygen

52
Q

Growth in presence of different oxygen concentrations
depends on a microbe’s metabolic processes:

A

• Electron transport chains (ETC)
• Final electron acceptor is → oxygen

53
Q

Obligate aerobes

A

dependent on oxygen from the
atmosphere (21.5%) for growth
• Most multicellular organisms

54
Q

Obligate anaerobe

A

oxygen is toxic, do not need it for
metabolism

55
Q

Microaerophiles

A

damaged by atmospheric oxygen (need
2-10% for growth)

56
Q

Facultative anaerobes

A

do not require oxygen for
growth…but grow better in its → presence

57
Q

Aerotolerant anaerobes

A

grow well with or without oxygen

58
Q

Oxygen is reduced to….

A

reactive oxygen species (ROS) –
toxic oxygen products
• Superoxide radical
• Hydrogen peroxide

59
Q

Aerobes produce protective enzymes that protect them
from ROS

A

• Superoxide dismutase (SOD)
• Catalase

60
Q

Strict anaerobic microbes lack or have very low quantities
of →

A

SOD or catalase

• These microbes cannot → tolerate O2
• Anaerobes must be grown without O2

61
Q

Microbial environments:

A

• Are complex and constantly → changing
• Expose a microorganism to overlapping gradients of
nutrients and environmental factors

62
Q

Microbes have evolved many responses to starvation and
environmental stress:

A

• Morphological changes (endospore formation)
• Enter stationary phase of growth curve
• Can use cellular components as → nutrients
• Numerous genes and proteins that help
• Viable but not culturable → state

63
Q

Where do most microbes grow?

A

Most microbes grow attached to surfaces rather than free
floating

• These attached microbes are members of complex, slime
enclosed communities called a → biofilm

64
Q

biofilm

A

complex, slime
enclosed communities

• Biofilms are everywhere in nature
• Can be formed on any conditioned surface

65
Q

Microbes reversibly attach to conditioned surface and
release polysaccharides, proteins, and DNA to form the

A

extracellular polymeric substance (EPS)

66
Q

Additional polymers are produced as microbes ____
and biofilm → ______

A

reproduce ; matures

67
Q

The EPS and change in attached organisms’ physiology
protect

A

microbes from harmful agents

• When formed on medical devices, such as implants,
serious infections can result
• Organism sloughing can contaminate water above biofilm
in a drinking water systems

Micro : Unit 1 (8 decks)

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