ch 4 archaeal cell structure Flashcards

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1
Q

gram-positive cell walls

A
  • composed primarily of peptidoglycan
  • may also contain teichoic acids
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2
Q

teichoic acids

A
  • polymers of glycerol
  • help maintain cell envelope
  • protect from environmental substances
  • may bind to host cells to initiate infection
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3
Q

gram-negative cell wall

A
  • thin layer of peptidoglycan surrounded by an outer membrane
  • outer membrane composed of lipids, lipoproteins, and lipopolysaccharides
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4
Q

cell envelope

A

the plasma membrane and any layers external to it

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5
Q

archaeal cell envelope

A

usually cell wall, S-layers, capsules, and slime layer

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6
Q

archaeal membrane

A

monolayer structure
- composed of unique lipid
change the fluidity and permeability of membranes
- branched chain hydrocarbons attached to glycerol by ether linkages

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7
Q

S-layer

A

can be up to 70nm thick
tether to the plasma membrane
resembles a protein canopy from the side or a geometric pattern on the top
can have carbohydrates for stabilization

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8
Q

nanotubes/nanopods

A

arrays of plasma membrane vesicles enclosed in the S-layer
- cargo packed within includes cytoplasmic contents, proteins, and nucleic acids
- thought to be important for intracellular gene transfer in thermophiles to protect DNA from denaturing in high temps

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9
Q

nutrient uptake in archaea

A
  • passive and facilitated diffusion
  • active transport (primary and secondary)
  • phosphoenolpyruvate: sugar phosphotransferase system (PTS) group translocation mechanism
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10
Q

ribosomes in archaea

A

same size as bacterial ribosomes
70S constructed of a 50S and 30S subunit
rRNA molecules similar in size to bacteria but nucleotide sequence differs
protein composition differs
- archaeal ribosomes have more r-proteins
- archaeal ribosomes more similar to eukarya
intrinsic resistance to tetracyclines and macrolides

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11
Q

nucleoid in archaea

A
  • usually not membrane bound
  • some evidence for polyploidy (bacteria are monoploid)
  • circular DS DNA that is supercoiled to fit
  • have histones - organize chromosomes into nucleosomes similar to eukaryotes
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12
Q

pili

A

composed of pilin proteins made in cytoplasm then anchor to a protein complex in the plasma membrane

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13
Q

cannulae

A

specialized archaeal pili
hollow, tubelike structures observed on the surface of thermophilic archaea
- function unknown, but daughter cells arising from a round of cell division remain connected to each other by cannulae

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14
Q

hami

A

specialized archaeal pili
resemble tiny grappling hooks
may function to attach cells to surfaces
seen in biofilm communities

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15
Q

archaella

A

archaeal flagella
thinner than bacterial flagella
have multiple proteins
filament is solid
rotation powered by ATP hydrolysis instead of proton motive force
direction moves cell forward or backwards
no runs and tumbles

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16
Q

methanogens

A

archaea that produce methane

17
Q

S-layer functions

A

in gram-negatives, adheres to outer membrane
in gram-positive, associated with peptidoglycan
protect from ion and pH fluctuations, osmotic stress, enzymes and predation
maintains shape and rigidity
promotes adhesion to surfaces
protects from host defenses
potential use in nanotechnology