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Hilary Term 1 > Prokaryotic Cell Structure and Function > Flashcards

Prokaryotic Cell Structure and Function Flashcards

1
Q

Describe the primary function of the cell membrane

A

permeability barrier between the cellular contents and the extraenous evironment, preventing leakage

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2
Q

Describe secondary function of the cell membrane

A

transportation of cellular inputs and outputs, such as nutrients, or toxic metabolic products, respectively

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3
Q

Describe tertiary function of the cell membrane

A

provides a protein achor, for which proteins can capitalise in order to fufill their repsective transportative, bioenergetic and chemotactic functions

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4
Q

Describe a function of cell membranes specific to unicellular organisms

A

energy conservation, as the site of generation and dissipation of the proton motive force in respiration

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5
Q

Describe the generalities of unicellular cell wall

A

composed of peptidoglycan (murein)

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6
Q

Describe peptidoglycan

A
  • aka murein
  • glycan tetrapeptide composed of repeating amino suagrs of N-acetylglucosamine and N-acetylmuramic acid, L-alanine, L-lysine, D-glutamic acid, diaminopimelic acid (DAP) and D-alanine
  • contains a lysozyme-sensitive glycosidic bond
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7
Q

Describe the characteristics of a Gram positive cell wall in bacteria

A
  • much thicker peptidoglycan layer (taking up to 90% of the cell wall’s composition) arranged in cross-linked cables
  • variable glycine interbridge between D-alanine and L-lysine
  • various protruding acid components
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8
Q

List some of the protruding acid components of Gram positive cell walls in bacteria

A
  • teichoic acid (glycerol or ribitol-phopsphate)
  • lipoteichoic acid
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9
Q

Describe the cell wall of Staphylococcus aureus

A
  • Gram-positive
  • interbridge is 5 glycine residues long
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10
Q

Describe the characteristics of a Gram-negative bacterial cell wall

A
  • outer membrane
  • peptide crosslinker between DAP and D-Alanine
  • components are made up of Lipid A , Core polysaccharide and O-specific polysaccharide segments
  • as necessitated by the presence of two membranes, there is periplasm space in between
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11
Q

Describe Lipid A

A

a non-glycerol-lipid saccharide of glucosamine phosphate

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12
Q

Describe Lipopolysachharides

A
  • endotoxins
  • result in sicknesses such as diarrhoea
  • eg. Lipid A
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13
Q

Describe the periplasm space

A
  • site for enzyme and protein binding
  • contains porins
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14
Q

What are porins (in the periplasm space of Gram negative bacterial cell walls)

A

protein trimers that form solute pores

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15
Q

Describe cell walls of Methanobacterial archaea

A
  • Pseudomurein compound
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16
Q

Describe Psuedomurein

A
  • lysozyme insensitive bond (B1,3; as opposed to B1,4)
  • N-Acetyltalosaminuronic acid element
  • retains its N-acetylglucosamine component and peptide crosslinkers
  • most commonly arranged in S-layer
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17
Q

Describe the polysaccharide capsule

A
  • outside the murein cell wall
  • extensive and strongly attached slime layer
  • can be perceived under staining with India ink
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18
Q

List the motile elements of bacteria outside of the cell wall

A
  • flagella
  • fimbriae
  • pilli
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19
Q

What are fimbriae?

A

very short protein filaments

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20
Q

What is the archaeal equivalent of a pillus?

A
  • the Hami
  • microscopic grappling hook, intended for the functional of cell attachment into a biofilm
  • for nutrient acquisition in benthic arenas
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21
Q

Describe the bacterial cell membrane

A
  • 6-8nm in diameter
  • phospholipid bilayer
  • both integral and peripheral membrane proteins that complete a variety of functions
  • strengthened by hopanoid, not sterol compounds
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22
Q

Describe the archaeal cell membrane

A
  • can be unilayered as well as bilyarered
  • ether, rather than ester bonds, joining the glycerophopshate groups to their fatty acid chains
  • contain proteinous elements
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23
Q

Describe the fatty acid chains of archaeal cell membranes

A

composed of isopropene-derived compounds

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24
Q

Describe the isopropene-derived compounds that make up the fatty acid chains of archaeal cell membranes

A
  • phytanyl
  • biphytanyl
  • sometimes crenarchaeol, in unilayered membranes
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25
Q

Describe the functions of the pills

A
  • HGT
  • transfer attenuated viruses from bacteria to bacteria to aid immunity
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26
Q

Describe storage polymers in bacterial cells

A
  • polyhydroxybutyrate
  • polyphosphate
  • elemental sulfure storage granules
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27
Q

Describe polyhydroxybutyrate in bacterial cells

A
  • acetyl-coA derived storage polymer
  • carbon storage
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28
Q

Describe polyphosphate in bacterial cells

A
  • ATP-derived storage polymer
  • phosphorus and energy storage
  • can produce ATP on hydrolysis
29
Q

Describe elemental sulfur storage granules in bacterial cells

A

found in purple photosynthetic S bacteria

30
Q

Describe B & C magnetosomes

A
  • cell membrane structure
  • found in magnetotactic bacteria
  • detect the magnetic pole of the Earth, allowing vertical bacteria migration down to lower oxygen concentrations
31
Q

How can magnetosomes detect the magnetic pole of the Earth?

A

Because the contain iron magnetite

32
Q

Describe gas vacuoles in bacterial cells

A
  • allow bacteria to undergo density adjustments
  • allowing vertical migration through water columns
33
Q

Describe the flagellum

A
  • 4 ring structure, hook and helical fiament
  • L ring; P ring; MS ring and the C ring
  • can take many structures
34
Q

Describe the flagella L ring

A

found within the LPS segment of the cell wall

35
Q

Describe the flagella P ring

A

found in the peptidoglycan

36
Q

Describe the flagella MS ring

A

in the membrane

37
Q

Describe the flagella C ring

A

in the cytoplasm

38
Q

Describe the flagella structure found in Salmonella and Escherichia coli bacteria

A

the radial peritrichous

39
Q

Describe potential flagella forms

A
  • radial peritrichous
  • lateral polar
  • singular tuft-like lophotrichous
  • double tuft-like amphitricous
40
Q

Describe the primary function of flagella

A

motility – rotation of the flagellum can result in both bidirectional (reversing) and unidirection (cessation) movement

41
Q

How is flagella rotation achieved?

A

Mot proteins receives energy from chemiosmotic proton flow, allowing rotation of the entire basal body

42
Q

What are the motor proteins referred to as

A
  • Mot
  • a stator
43
Q

Describe flagellum assembly

A
  • must grow outwards from the bacterial cytoplasmic base
  • from the MS and C rings, to the Mot proteins, to the P ring, L ring, early hook, Capped late hook, the hook-filament junction and finally the filament itself
  • during assembly flagellin can migrate through the core of the flagellum, allowing assembly of the tip and the filament
44
Q

Describe flagellin

A

proteinous monomer

45
Q

Describe the core of the flagellum

A

hollow

46
Q

Describe the archaeal flagellum equivalent

A
  • archaellum
  • half the width of a bacterial flagellum
  • uses ATP to rotate
47
Q

Describe archaellum assembly

A

FlI and FlaX external and FlaJ rotary motor proteins, which roatte the filament

48
Q

Describe the archaellum filament

A

protrudes from the S-layer membrane

49
Q

Describe the secondary function of flagella and archaella

A
  • faciliation of chemotaxis
  • walking is biased by chemical gradients over time
50
Q

Describe the method of walking in flagella and archaella

A
  • random in three dimensions
  • both running and tumbling
51
Q

Describe the flagella of Spirochaetes Treponema pallidum and Borrellia burgdorferi

A

rigid endoflagella inside the flexible outer sheath, in the periplasm space

52
Q

Describe the structure of endoflagella

A

attached to one end of the protoplasmic cylinder

53
Q

Describe the protoplasmic cylinder

A

generally helical

54
Q

Describe endoflagella rotation

A
  • directly results in sheath rotation
  • corkscrew action
  • allows for crossing of bodily mucus membranes
55
Q

What is the contrivance of endoflagella

A

crossing of bodily mucus membranes of supreme importance to pathogenic, parasitic bacteria

56
Q

Describe gliding motility in bacteria and archaea

A

slime, or pilli-mediated pulling forces

57
Q

Describe gliding motility in Flavobacterium johnsoniae

A
  • gliding proteins released from the cell surface
  • pulling force in antithesis to the cell motion
  • requires a proton motive force
58
Q

Describe swarming behaviours in bacteria

A
  • mediated via the pilli
  • when bacteria exist on surfaces
59
Q

Describe retractile spores in bacteria

A
  • thermo-, osmo- and chemical resilience
  • death will only occur at typically 121 degrees Celsius
60
Q

Describe the structure of bacterial retractile spores

A
  • exosporium outside the spore coat, itself outside of the core wall
  • inside of this is the cortex and finally the DNA
61
Q

Describe the physiology of bacterial retractile spores

A
  • very little water
  • internal pH is one unit lower than that of its parent vegetative cell
62
Q

Why do bacterial retractile spores exhibit slightly acidic pH

A
  • high volume of constituent dipicolonic acid
  • small acid soluble spore proteins
63
Q

Describe the formation of bacterial retractile spores

A
  • during germination of a vegetative cell
  • assymetric cell division of vegetative cells post-growth is the commitment to sporulation Stage I
64
Q

Describe Stage II of bacterial retractile sporulation

A
  • pre-endospore forms within the vegetative mother cell
  • cell becomes septated
65
Q

Describe Stage III of bacterial retractile sporulation

A
  • endospore becomes engulfed
  • cell is now sporulating cell
66
Q

Describe Stage IV of bacterial retractile sporulation

A
  • formation and differentiation of the cortex, cell wall and cytoplasmic membrane
67
Q

Describe Stage V of bacterial retractile sporulation

A
  • formation of the spore coat
  • uptake of calcium ions, SASps and the dipicolinic acid
  • gives the spore its lower pH
68
Q

Describe Stage VI of bacterial retractile sporulation

A

results in maturation

69
Q

Describe Stage VII of bacterial retractile sporulation

A

results in cell lysis, and mature endospore release

Hilary Term 1 (61 decks)

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