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BIMM 120 > Week 2 Cell Structure II + Bac/Arc Mole. Basis > Flashcards

Week 2 Cell Structure II + Bac/Arc Mole. Basis Flashcards

1
Q

Cytoplasmic Membrane (Integral membrane proteins and phospholipids)

A
  1. Permeability barrier: no leakage + regulation
  2. Protein anchor: transport, chemotaxis, bioenergetics
  3. Energy conservation: proton motive force (PMF)
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2
Q

Physical effects of biological membranes

A

Fluid phase (liquid-crystalline) –> gel phase UNDER LOW T and HIGH P (poor membrane)
> must prevent FREEZING by changing lipid composition via unsaturated FA
> Saturated: palmitic acid
> Unsaturated: cis-Vaccenic Acid

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3
Q

Bacterial FA

A
  1. S/US and branch-chain acyl moieties (8-22C)
  2. Opposing fatty acyl chain form lipid bilayer
    > **Glycerol-3-Phosphate backbone, ester-linkage
  3. Profiling: extract FA –> derivatize to FA methyl esters –> chromatography or spectrometry
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4
Q

Archaea FA (mono 40C/bilayer 20C)

A
  1. Top to down: phosphate + glycerol –> phytanyl chains with ETHER linkage
  2. Glycerol-3-phosphate backbone
  3. Extremophilic: lipid melts at high T and breakdown/H+ leak at low pH
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5
Q

Surface Structure: Capsules and Slime Layers (GLYCOCALYX)

A
  1. Protein/polysac extending
  2. Capsules: tight matrix, sturdy cell adhesion
  3. Slime Layer: loose (NOT S-layer)
  4. Highly specific and regulated: biofilm attachments, protection from phagocytosis, chemical/desiccation prevention, nutrient absorption
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6
Q

Surface Structure: Fimbriae, Pili and Hami

A
  1. Fimbriae: thin, protein EC filaments (a lot); tight attachment (surface and cell2cell); pathogenesis
  2. Pili: thick, protein EC filaments (sparse)
    > Type I lectins (surface)
    > Type IV twitching
    > DNA conjugation: sex pili
    > Viral receptors
    > Pathogenesis
  3. Hami (Archaea): nano-hooks
    > SM1 euryarchaeota from sulphidic springs
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7
Q

Surface Structure: Flagella

A
  1. Swimming locomotion with stiff protein helix (CCW=F, CW=R/tumble; 300 rot/sec)
  2. Categories:
    > Polar: unidirection (stops and reorients)
    > Peritrichous/lophotrichous: bundle unravels and cell tumbles
  3. Chemotaxis: random or directed movements based on attractant presence (chemoreceptors sense temporal gradients; sense changes in concentration over time)
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8
Q

Surface Structure: Flagella Motor

A
  1. Up to down: LPS, peptidoglycan, basal bodies (fli proteins/motor switch), mot proteins GENERATING TORQUE, cytoplasmic membrane
    > G+ has no L ring/LPS
    > Fli proteins: F/R on signa
    > Proton Turbine Model: H+ translocation via Mot proteins –> electrostatic forces on charges in rotor (MS/C) ring proteins –> spin (1000 H+ or Na+/rot)
  2. Integral flagella:
    > Spirochetes (perplasmic space): Lyme, syphilis
    > Viscous media: polar attachment allows cell to corkscrew via gyration
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9
Q

Inclusions: Carbon Storage Polymers

A
  1. Poly-B-Hydroxybutyrate (polyesters of hydroxy FA) in excess C and nutrient limitation
  2. Hydrocarbon-degrading microbes can store C in wax polymers
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10
Q

Inclusions: Inorganic Ion Storage

A
  1. Polyphosphate (PO4) in limited nutrient; needed for nucleic acid and phsopholipid synthesis; direct ATP making
  2. Sulfur globules (S0): form in periplasm –> when limited becomes further oxidized to SO4
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11
Q

Inclusions: Magnetic Particles

A
  1. G- bacteria (B and Y proteobacteria) only due to AEROTAXIS
  2. Single polar flagellum; aquatic microaerophilic
  3. Produce Fe3S4; has dipole moment
  4. IC Fe3O4 biomineralization: magnetosome membrane within outer and CM
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12
Q

Inclusions: Gas Vesicles

A
  1. Cyanobacteria and planktons

2. Confer buoyancy by decreasing cell density: has interlocking proteins (watertight but gas permeable)

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13
Q

Inclusions: Endospores

A
  1. Survival structure (temp, drying and nutrient)
  2. G+ only (NOT archaea); core dehydration (high heat tolerance); exosporium and spore coat (chemical resilience)
  3. Life cycle: activation, germination and outgrowth
    > vegetative cell develops spore when sensing danger –> spore matures and is germinated when all is good
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14
Q

Biofilms (Mono/multi-species)

A
  1. Surface attachment assisted by pili and fimbriae –> colonization (polysac formation and IC communication) –> development
  2. Adhesive property: resilient to eradication with dense EC matrix as filter –> quorem sensing and response by modulating GE
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15
Q

Similarities in Bac/Arc (oppo of Eukarya)

A
  1. Covalently closed and circular single DNA (rare introns, repressors in promoters)
  2. DNA/reverse gyrase and Restriction enzymes
  3. 70S ribosomes, 16S/23S rRNAs
  4. Operons and Plasmids present (polycistronic mRNA)
  5. No Capping and Poly A
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16
Q

Differences within Bac/Arc

Archaea more similar to Eukarya

A 
1. Bacteria:
> Ester-linked lipids
> Chlorophyll-based photosynthesis
> No histones, no ribosome sensitivity to diphtheria toxin, formylmethionine initiator tRNA, no TF
2. Archaea:
> Ether-linked lipids
> No chlorophyll-based photosynthesis
> Has histones, has sensitivity, methionine initiator tRNA, TF required
17
Q

Bac/Arc DNA Processing

A
  1. DNA gyrase (topoisomerase II): negative DNA supercoils
  2. Reverse gyrase: positive supercoils (bac/arc enhanced thermostability)
    > double-stranded break resealed (ciprofloxacin + novobiocin)
  3. Restriction endonucleases: dsDNA degradation; protection from foreign invaders
18
Q

Bac Transcription: Sigma Factor

A

Proteins required for initiating RNA synthesis
> Mediate RNAP binding to promoter; highly conserved and specific at -10 and -35 (stationary phase growth, N-utilization, iron transport, heat shock, etc)

19
Q

Bac/Arc Transcription: Polycistronic mRNA

A
  1. Often organized into operons (genes coding for proteins colinear on chromosome)
20
Q

Bac/Arc Transcription: Repressor Proteins

A
  1. Gene transcription blocked by proteins binding to promoter –> RNAP doesn’t bind
    > Eukarya bind to distant enhancer regions bound to DNA to prevent transcription
21
Q

Bac/Arc Translation: rRNA Genes (16S/5S/23S)

A
  1. Bac: arranged in operons
  2. Arc: scattered throughout genome
  3. Euk: 5S, 5.8S, 18S, 28S
22
Q

Bac/Arc Translation: 70S ribosomes

A

Two subunits: 30S and 50S
> 30S: 16S rRNA, 21 proteins
> 50S: 5S/23S rRNA, 34 proteins (Azithromycin/Zithromax)

BIMM 120 (8 decks)

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