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CMMB 343 > CMMB 343 midterm 1 > Flashcards

CMMB 343 midterm 1 Flashcards

1
Q

what are some problems for cells at low temp?

A

proteins, membrane, DNA, RNA all too rigid

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2
Q

what are some solutions to low temp problems for cells?

A

increase membrane fluidity, decrease RNA stability (less GC), increase flexibility of enzymes

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3
Q

Almost all cultured ?? are sulfur or hydrogen-oxidizing.

A

hyperthermophiles

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4
Q

what is different between Archaea membranes and Eukarya/Bacteria membranes?

A

Archaea have isoprene chains and are bound to ether linkages while E/B have fatty acid tails bound with ester linkages

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5
Q

what are the major functions of cell membrane?

A
  1. Cell’s permeability barrier
  2. Anchors key proteins
  3. Major role in energy conservation and consumption
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6
Q

how many bacteria cells are there in 1 g of soil? what % of biomass do they account for on Earth?

A

1,000,000,000

20-50%

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7
Q

Conan the bacterium

A
  • Deinococcus radiodurans
  • most radiation resistant organism (>1000 times dose that will kill humans)
  • multiple copies of its genome, switches which one is in use while others repair
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8
Q

Louis Pastuer

A
  • Discovered that alcoholic fermentation was a biologically mediated process
    – Disproved theory of spontaneous generation
    – Led to the development of aseptic technique
    – Developed early vaccines (rabies)
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9
Q

Robert Koch

A

– Demonstrated the link between
microbes and infectious diseases (CAUSATIVE AGENTS of anthrax and tuberculosis)
– Koch’s postulates
– Developed techniques (solid media) for obtaining pure cultures of microbes, some still used today (1st to use agar plates)
– Awarded Nobel Prize for Physiology and Medicine in 1905

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10
Q

Sergei Winogradsky

A
  • father of microbio
  • W column
  • proposed chemolithotrophy (oxidation of inorganic compounds to get energy, autotrophy - carbon from CO2)
  • linked specific bacteria to specific biogeochemical transformations (N and S cycles)
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10
Q

Koch’s postulates

A

a set of criteria for proving that a given microorganism causes a disease

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11
Q

W. column: what gradients exist?

A

bottom-up = sulfide concentration (highest at bottom)

top-down = oxyfgen concentration (highest at top, more areboic bacteria - cyanobacteria at very top layer)

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12
Q

father of bacterial taxonomy? what did the OG taxonomy include?

A

Ferdinand Cohn

4 groups based on shape: cocci, rod, sphere, filamentous

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13
Q

chemolithotroph

A

energy source = inorganic chemicals (H2, H2S, NH4+, etc)

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14
Q

chemoorganotroph

A

energy source = organic chemicals (sugars, proteins, etc)

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15
Q

heterotroph

A

carbon source = organic chemicals

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16
Q

autotroph

A

c source = CO2

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17
Q

early tree of life made by? based on?

A

Haeckel, based on belief that evolution strives towards higher complexity

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18
Q

Universal tree of life: newest version

A

by Carl Woese who used DNA not just morphology, used ribosomal RNA since every living thing has ribosomes

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19
Q

why is important to include sucrose in cell suspensions?

A

sucrose lowers the water activity of the cell suspension, preventing too much water from leaving the cells causing lysis

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20
Q

if the water activity is higher inside the cell than in the solution, what will happen?

A

water moves out of cell

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21
Q

what is the salt-in strategy?

A
  • cells will accumulate KCl
  • cheaper method energetically
  • salts damage enzymes tho
  • mostly Archaea
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22
Q

what is the compatible solutes strategy?

A
  • accumulate organic solutes (the cells make them)
  • more expensive
  • Bacteria and Eukarya
  • no damage to enzymes
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23
Q

plasmolysis

A

cell shrivels from negative pressure from water leaving the cell, cell wall is ripped off

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24
Q

water moves from areas of ? water activity to ? water acitivity

A

high to low water activity (aw)

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25
Q

high solute content = ? aw

A

low water activity

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26
Q

aerobes

A

need O2 for respiration

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27
Q

microaerophiles

A

need O2, but at low levels (less than atmospheric levels), have some enzymes that are damaged by O2

28
Q

facultative anaerobes

A

can respire O2, but don’t require it

29
Q

aerotolerant anaerobes

A

don’t respire O2, but are NOT damaged by it (has no effect on them)

30
Q

obligate anaerobes

A

don’t respire O2 and ARE damaged by it (highly sensitive)

31
Q

what is something that can be used to determine which of the 5 oxygen related species and organism is?

A

thioglycolate broth

a complex medium that separates microbes based on O2 requirements

32
Q

why is oxygen toxic?

A

exposure to O2 yeilds toxic byproducts:
- superoxide (O2-)
- hydrogen peroxide (H2O2)
- hydroxyl radical (OH.) which is the WORST

33
Q

what do these do?
1. catalase
2. peroxidase
3. superoxide dismutase
4. superoxide dismutase/catalse combo
5. superoxide reductase

A
  1. 2H2O2 –> 2H20 + O2
    (gets rid of hyd peroxide)
  2. H2O2 + NADH –> 2H20
    (rid of hyd peroxide)
  3. 2 O2- –> H2O2
    (rid of superoxide, but makes hydrogen peroxide, now need 1 or 2)
  4. 4O2- –> 2H2O + 3O2
  5. reduces O2- to H2O2, oxidizes rubredoxin in process
34
Q

gram positive cell

A
  • thick peptidoglycan cell wall
  • one (innner) membrane
  • purple on gram stain
35
Q

gram-negative cell

A
  • outer membrane
  • periplasm (contains thin peptidoglycan cell wall)
  • cytoplasmic (inner) membrane
  • pink/red on gram stain
36
Q

True or false: Membranes do not allow the passage of ions, sugars or amino acids (large or strongly polar molecules). These must be transported.

A

true

37
Q

are saturated or unsaturated fatty acid tails preferred for psychrophiles?

A

unsaturated, the double bonds in the tails don’t pack as tightly, make the membrane more flexible which is needed in colder temps

38
Q

thermophiles prefer (saturated/unsaturated) fatty acid tails in their membranes?

A

saturated

39
Q

?? lipids lack fatty acids, but have isoprenes instead

A

Archaeal

40
Q

? can exist as lipid monolayers, bilayers, or mix of both

A

archaeal membranes

41
Q

why are monolayers beneficial to certain Archaea?

A

less membrane fluidity, can survive in hotter temps (thermophiles)

42
Q

are ether or ester linkages more stable?

A

ether (Archaea)

43
Q

explain the 3 transport protein mechanisms

A
  1. simple transport: transmembrane transport protein
  2. group translocation: series of proteins
  3. ABC system: 3 components, bing protein, ATP-hydrolyzing protein, transmembrane prot
44
Q

most ? are Gram neg

A

bacteria (not Bacteria)

45
Q

gram neg or pos are often pathogens?

A

GRAM POS

46
Q

are g - or + better halophiles? why?

A

gram pos cells are better halophiles, have and increased internal pressure,

47
Q

do gram neg or pos cells have crosslinks btw DAP and D-alanine carboxyls on adjacent glycan strands

A

gram-negative

48
Q

teichoic acids only found in? what do they do?

A

the peptide wall of gram-positive cells

they are antigenic (kill bacteria), maintain cell shape and porosity of wall, capture cations (Ca2+, Mg2+), phosphate reservoir, regulate cell wall turnover (autolysins)

49
Q

periplasm

A

space btw cytoplasmic and outer membranes in gram neg

50
Q

what 3 keys structures make up Lipopolysaccharides?

A
  • O-specific polysaccharide
  • core polysaccharide
  • Lipid A (endotoxin)
51
Q

the cell wall and membrane together make up?

A

cell envelope

52
Q

What is transglycosylase role in peptidoglycan synthesis?

A

Peptidoglycan synthesis requires two activities: transglycosylase (TG) to polymerize the glycan chains and transpeptidase (TP) to catalyze peptide cross-linking between two adjacent glycan chains.

53
Q

how come penicillin can be used in humans to target bacteria?

A

eukaryotes don’t have peptidoglycan, but bacteria do and autolysin activity continues causing autolysis of bacteria cell

54
Q

what does penicillin do?

A

inhibits transpeptidase activity - leads to cell death

55
Q

beta-lactamase

A

provides bacterial cells with antibiotic resistance (ex it becomes resistant to penicillin)

56
Q

what can freely pass through the cytoplasmic membrane?

A

dissolved O2 and simple alcohols

57
Q

LPS (Lipopolysaccharides are unique to?

A

outer membrane of gram neg bacteria

58
Q

bacterial cells that move can only sense a gradient by identifying ? changes and NOT ? differences `

A

they sense temporal changes

NOT spatial changes

cuz they r small

59
Q

in general prokaryotes or eukaryotes grow in higher temps?

A

prokaryotes

60
Q

are phototrophic or non phototrophic organisms able to grow at higher temps?

A

NON-PHOTOTROPHIC

61
Q

peptide INTERBRIDGE is present in?

A

gram pos Bacteria

62
Q

the presence of diglycerol tetraethers in some archaea indicate what kind of cell membrane?

A

monolayer

63
Q

The person who described the “wee animalcules” was

A

Antoni van Leuuwenhook

64
Q

_______ are charged molecules that are partially responsible for the ________ charge of the Gram-positive bacterial cell surface.

A

teichoic acids

negative

65
Q

Which of the following is an example of a cultured marine chemoorganotrophic bacterium that contains proteorhodopsin and is a member of the SAR11 clade?

A

pelagibacter

66
Q

what is ANI and what is it most commonly used for?

A

average nucleotide identity, used for genome sequencing

67
Q

what inhibits the FtsZ ring?

A

MinCD

68
Q

endospores are only in gram ?

A

positive

CMMB 343 (3 decks)

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