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Flashcards in lecture 1.7 Deck (78):
1

What are the reproductive strategies of Eukaryotic microbes

asexual or sexual
haploid or diploid

2

What are the reproductibe strategies of Bacteria/Archaea

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

3

How do most bacteria divide?

binary fission

4

What are the processes functioning during binary fission?

DNA replication and partition
cytokinesis

5

terminus=

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

6

replisome=

group of proteins needed for DNA synthesis

7

origin=

site at which replication begins

8

describe DNA replication of bacteria

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

9

septation=

formation of cross walls between daughter cells

10

List the steps for septation

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

11

What is protein FtsZ?

tubulin homologue, found in most bacteria and archaea
polymerization forms Z ring, filaments of meshwork

12

What does MinCDE system do

limits the Z ring to the center of the cell

13

Describe how the MinCDE system works

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

14

What are the three protiens of the MinCDE system?

MinC, MinD, MinE

15

what determines cell growth AND cell shape?

peptidoglycan synthesis in bacteria

16

Penicillin Binding Protiens (PBPs)=

link peptidoglycan strands and catalyze controlled degradation for new growth

17

Autolsyins=

PBP enzymes that degrade peptidoglycan and site new units added

18

Describe Cocci divisome

new peptidoglycan forms only at the central septum

19

How does the cocci divisome work

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

20

How do rods grow and seperate

elongate prior to septation
MreB determines cell diameter and elongation as Z ring forms in center

21

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

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

22

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

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

23

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

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

24

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

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

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