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Biology 438 > lecture 1.7 > Flashcards

lecture 1.7 Flashcards

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1
Q

What are the reproductive strategies of Eukaryotic microbes

A

asexual or sexual

haploid or diploid

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2
Q

What are the reproductibe strategies of Bacteria/Archaea

A

haploid
binary fission, budding, filamentous, depending on species
replicate and segregate the genome prior to division

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3
Q

How do most bacteria divide?

A

binary fission

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4
Q

What are the processes functioning during binary fission?

A

DNA replication and partition

cytokinesis

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5
Q

terminus=

A

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

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6
Q

replisome=

A

group of proteins needed for DNA synthesis

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7
Q

origin=

A

site at which replication begins

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8
Q

describe DNA replication of bacteria

A

Most bacterial chromosomes are circular
Single origin of replication
DNA replication proceeds in both directions from the origin
Origins move to opposite ends of the cell
hits terminus and stops

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9
Q

septation=

A

formation of cross walls between daughter cells

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10
Q

List the steps for septation

A

selection of site for septum formation
assembly of Z ring
linkage of Z ring to plasma membrane (cell wall)
assembly of cell wall synthesizing machinery
constriction of cell and septum formation

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11
Q

What is protein FtsZ?

A

tubulin homologue, found in most bacteria and archaea

polymerization forms Z ring, filaments of meshwork

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12
Q

What does MinCDE system do

A

limits the Z ring to the center of the cell

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13
Q

Describe how the MinCDE system works

A

MinC, MinD, MinE oscillate from one side of cell to other
link Z ring to cell membrane
Z ring constricts and cell wall synthesis of septal wall

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14
Q

What are the three protiens of the MinCDE system?

A

MinC, MinD, MinE

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15
Q

what determines cell growth AND cell shape?

A

peptidoglycan synthesis in bacteria

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16
Q

Penicillin Binding Protiens (PBPs)=

A

link peptidoglycan strands and catalyze controlled degradation for new growth

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17
Q

Autolsyins=

A

PBP enzymes that degrade peptidoglycan and site new units added

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18
Q

Describe Cocci divisome

A

new peptidoglycan forms only at the central septum

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19
Q

How does the cocci divisome work

A

FtsZ determines site of cell wall growth
FtsZ may recruit PBPs for synthesis of septum
only at the central septum

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20
Q

How do rods grow and seperate

A

elongate prior to septation

MreB determines cell diameter and elongation as Z ring forms in center

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21
Q

What happens in the call wall in stage one of cell growth of cocci

A

spherical cells build peptidoglycan only at the midcell. One daughter cell will have an old cell wall hemisphere and one will have a new cell wall hemisphere

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22
Q

What happens in the cell wall of stage one of cell growth in rods?

A

During growth, prior to division, new cell wall is made along the sides of the cell but not at the poles. The placement is thought to be determined by the position of MreB homologues

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23
Q

What happens in the cell wall in stage two of cell growth of cocci

A

FtsZ polymerization forms a Z ring and new cell wall growth is confined to the midcell

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24
Q

What happens in the cell wall of stage two in cell growth of rods?

A

Rod-shaped daughter cells are formed with one new pole and one old pole

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25
extremophiles=
grow under harsh conditions that would kill most other organisms
26
osmotolerant=
able to grow over wide ranges of water activity or osmotic concentration
27
halophile=
requires high levels of sodium chloride, usually above about 0.2 M, to grow grow optimally in the presence of NaCl or other salts at a concentration above about 0.2M
28
Acidophile=
growth optimum between pH 0-5,5
29
Neutrophile=
growth optimum between pH 5.5-8.0
30
Alkaliphile=
growth optimum between pH8.0-11.5
31
Psychrophile=
grows at 0C and has an optimum growth temperature of 15C or lower
32
Psychrotroph=
Can grow at 0-7C, has an optimum between 20 and 30C and a maximum around 35C
33
Mesophile=
has growth optimum between 20 and 45C
34
Thermophile=
Can grow at 55C or higher optimum often between 55-65C
35
Hyperthermophile=
has an optimum between 85 and about 113C
36
Obligate aerobe=
competely dependent on atmospheric O2 for growth
37
Facultative anaerobe=
Does not require O2 for growth but grows better in its presence
38
Aerotolerant anaerobe=
grows equally well in the presences or absence of 02
39
Obligate anaerobe=
does not tolerate O2 and dies in its presence
40
Microaerophile=
required O2 levels between 2-10% for growth and is damaged by atmospheric O2 levels (20%)
41
Piezophile (barophile)=
growth more rapid at high hydrostatic pressures
42
What happens in a hypotonic solution (lower osmotic concentration)
water enters the cell | cell swells may burst
43
What happens in a hypertonic solution (higher osmotic concentration)
water leaves the cell | membrane shrinks from the cell wall (plasmolysis) may occur
44
How do cells respond to hypotonic medium
Reduce osmotic concentration of cytoplasm | mechanosensitive (MS) channels in plasma membrane allow solutes to leave
45
How do cells respond to hypertonic medium
Increase internal solute concentration with compatible solutes to increase their internal osmotic concentration solutes that are accumulated are compatible with metabolism and growth
46
Halophiles=
grow optimally in the presence of NaCl or other salts at a concentration above about 0.2M
47
extreme halophiles=
require salt concentrations of 2M and 6.2M cytoplasm has extremely high concentrations (up to 6 M) of KCl cell wall, proteins, and plasma membrane require high salt to maintain stability and activity
48
Acidophiles=
growth optimum between pH 0 and pH 5.5
49
Neutrophiles=
growth optimum between pH 5.5 and pH 7
50
Alkaliphiles (alkalophiles)=
growth optimum between pH 8.5 and pH 11.5
51
How do most microbes maintain an internal pH near neutrality?
the plasma membrane is impermeable to proton | exchange potassium for protons
52
How do cells response to acid/acidic conditions?
pump protons out of the cell | some synthesize acid and heat shock proteins that protect proteins
53
How do microorganisms change the pH of their habitat
by producing acidic or basic waste products
54
How does temperature effect growth?
cannot regulate their internal temperature Enzymes have optimal temperature at which they function optimally and high temperatures may inhibit enzyme functioning and be lethal Organisms exhibit distinct cardinal growth temperatures: minimal, maximal, and optimal
55
Psychrophiles=
0 C to 20 C
56
Psychrotrophs=
0 C to 35 C
57
Mesophiles=
20 C to 45 C
58
Thermophiles=
55 C to 85 C
59
Hyperthermophiles=
85 C to 113 C
60
How are protein structures stabilized differently
more H bonds more proline chaperones
61
What are the various ways a membrane can be stabilized
``` more saturated, more branched and higher molecular weight lipids ether linkages (archaeal membranes) ```
62
What stabilizes DNA
Histone-like proteins
63
Aerobe=
grows in presence of atmospheric oxygen (O2) which is 20% O2
64
Obligate aerobe=
requires O2
65
Anerobe=
grows in the absence of O2
66
Obligate anaerobe=
usually killed in presence of O2
67
Microaerophiles=
requires 2–10% O2
68
Facultative anaerobes=
do not require O2 but grow better in its presence
69
Aerotolerant anaerobes=
grow with or without O2
70
What is the basis for oxygen sensitivies?
Oxygen easily reduced to toxic reactive oxygen species (ROS) | Aerobes produce protective enzymes
71
What are some toxic reactive oxygen species
superoxide radical: O2- hydrogen peroxide: H2O2 hydroxyl radical: HO-
72
What are some examples of protective enzymes that aerobes produce?
superoxide dismutase (SOD) catalase peroxidase
73
What do all strict anaerobic microorganisms lack/very low quanities of?
superoxide dismutase | catalase
74
Barotolerant=
adversely affected by increased pressure, but not as severely as nontolerant organisms
75
Barophilic (peizophilic) organisms=
require or grow more rapidly in the presence of increased pressure change membrane fatty acids to adapt to high pressures
76
How do Barophilic (peizophilic) organisms adapt to high pressures
change membrane fatty acids
77
Describe UV radiation on cells
causes formation of thymine dimers in DNA requires direct exposure on microbial surface DNA damage can be repaired by several repair mechanisms
78
What do carotenoid pigments do
protect many light-exposed microorganisms from photooxidation

Biology 438 (13 decks)

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