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Microbiology Test 1 > Chapter 3 - PPT > Flashcards

Chapter 3 - PPT Flashcards

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1
Q

What is morphology?

A

Cell shape

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2
Q

What are the 3 major cell morphologies?

A

Coccus (pl. cocci): spherical or ovoid
Rod: cylindrical shape
Spirillum: spiral shape
Cells with unusual shapes

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3
Q

Coccus

A

Spherical or ovoid

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4
Q

Rod

A

Cylindrical shape

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5
Q

Spirillum

A

Spiral Shape

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6
Q

Why is morphology considered a poor predictor?

A

Does NOT predict physiology, ecology, phylogeny, etc. of organism
Bacteria and Archaea morphologies look identical but inherent differences

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7
Q

What are some possible selective forces leading to morphology?

A

Optimization for nutrient uptake
Surface-to-volume ratio
Motility

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8
Q

Bacteria and Archea cells size

A

Range: 0.2 µm to > 700 µm
Most: 0.5 and 4.0 µm wide and <15 µm long
Average: rod 1 x 2 µm
Smallest: M. pneumoniae 0.2 µm
Largest: T. namibiensis 750 µm

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9
Q

Eukaryotic cell size

A

Range: 10 to >200 µm in diameter

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10
Q

Advantages to being small?

A
  1. Small cells have more surface area relative to cell volume than large
  2. Support greater nutrient exchange per unit cell volume
    Tend to grow faster
    Support larger population
  3. Advantages to being small
    More rapid rate of evolution
    Faster growth rate
    Mutations have stronger effect
    Smaller genome, usually haploid
    Ability to adapt rapidly to changing environment
    Ability to exploit new habitats
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11
Q

Lower limit to house essentials?

A

~0.15 µm

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12
Q

What is the limiting factor for largeness?

A

Nutrient uptake

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13
Q

Cytoplasmic membrane Bacteria and Archaea:

A

Thin structure that surrounds the cell
6–8 nm thick
Vital barrier separating cytoplasm from environment
Highly selective permeable barrier
enables concentration of specific metabolites and excretion of waste products
Little protection from osmotic lysis

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14
Q

Composition of Membranes

A

General structure is phospholipid bilayer
Contain both hydrophobic and hydrophilic components

Different chemical forms - Variation in the groups attached to the glycerol backbone
Fatty acids point inward to form hydrophobic environment
Hydrophilic portions remain exposed to external environment or the cytoplasm

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15
Q

What is a phospholipid?

What is the round part?

What is the squigly part?

A
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16
Q

Membrane Proteins

What are the parts?

A

Hydrophobic region and hydrophilic region(s)
Hydrophobic spans the membrane
Hydrophilic region(s) extend to exterior and/or interior
Exterior example: substrate binding or transport
Interior example: energy-yielding reactions

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17
Q

Integral membrane proteins

A

Firmly embedded in the membrane

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18
Q

Anchored Proteins

A

Anchored and extramembrane regions

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19
Q

Peripheral Membrane Proteins

A

Not embedded but firmly associated

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20
Q

Picture

  1. Transmembrane proteins
  2. Peripheral membrane proteins
  3. Phospholipid bilayer
  4. Integral membrane proteins
A
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21
Q

Bacteral and Eukarya Membrans

A

Ester linkages in phospholipids, only
Fatty acids, only
Straight carbon chain, only
Bilayer, only

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22
Q

Archaea Cytoplasmic membrane

A

Ether linkages in phospholipids
Lack fatty acids, have repeating isoprenes instead
Major lipids: glycerol diethers (20C) and teraethers (40C)
Side chains and/or rings (ex: cyclohexyl)
Can exist as lipid monolayers, bilayers, or mixture

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23
Q

Which is Bacteria and Eukarya?

Which is Archaea?

A

Left is Archaea

Right is Bacteria

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24
Q

Considering the backbone linkages what is the difference between Bacteria and Eukarya, vs Archaea?

A
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25
Descibe the image:
Lipid Monolayer of an Archaea Ether linkage C40
26
Label 1. Glycerophosphates 2. Membrane Protein 3. Fatty acid chain
1. Head (blue) 2. Brown 3. Orange
27
Permeability Barrier
Prevents leakage of solutes in or out of cell Transport polar and charged molecules Transport proteins accumulate solutes against the concentration gradient
28
Functions of the Cytoplasmic Membrane
1. Permeability Barrier 2. Protein Anchor 3. Energy conservation (proton motor force)
29
What are the 3 major classes of Transport systems?
Simple Transport Group Translocation ABC
30
What are the 3 possibel transport events?
Uniporters Symporters Antiporters
31
Uniporter
transport in one direction across the membrane
32
Symporters
function as co-transporters
33
Antiporters
transport a molecule across the membrane while simultaneously transporting another molecule in the opposite direction
34
Label
Yellow - Uniport Red - Symport Blue - Anitport
35
Why have a cell wall?
Cells must withstand pressure and prevent lysis (bursting) Pressure due to osmotic differences ~ 2 atm (~ car tire) Confer shape and rigidity
36
Peptidoglycan
Rigid layer that provides strength to cell wall Polysaccharide composed of: (N-acetylglucosamine and N-acetylmuramic acid Amino acids Lysine or diaminopimelic acid (DAP)) Repeating unit: glycan tetraether Cross-linked and arranged differently in gram-negative bacteria and gram-positive bacteria
37
The Cell Wall of Bacteria: Gram Positive and Gram Negative
38
Picture Gram Positive Bacteria 1. Chemical layers 2. general strucutre 3. Gram staining results
39
% cell wall peptidoglycan G+
Can contain up to 90% peptidoglycan
40
Teichoic acids/Lipoteichoic acids.
Common to have teichoic acids (acidic substances) embedded in the cell wall Lipoteichoic acids: teichoic acids covalently bound to membrane lipids
41
Gram Positive Cell Wall 1. Teichoic acid/Lipoteichoic acid 2. Wall assoiciated protein 3. Membrane bound protein 4. Peptidoglycan 5. Cytoplasmic membrane
1. orange long squiggles 2. upper blobs 3. lower blobs 4. lined up top 5. lower balls and squiggles
42
Picture Gram negative bacteria 1. chemical layers 2. general 3. gram stain results
43
Gram negative bacteria: Outer membrane General description
Total cell wall contains ~10% peptidoglycan Most of cell wall composed of outer membrane aka lipopolysaccharide [LPS] layer Core polysaccharide and O-polysaccharide LPS replaces most phospholipids in outer half of outer membrane Endotoxin: the toxic (intestinal) component of LPS
44
Gram negative Bacteria 1. Outer membrane 2. Periplasm 3. Cytoplasmic Membane 4. Cell wall 5. Polysaccharide/lipopolysaccharides 6. Porin 7. Peptidoglycan
1. outer memebrane 2. Periplasm - space between membrane layers and peptidoglycan 3. cytoplasmic membrane 4. well wall - outer membrane and peptidoglycan 6. porin- passage through outer layer 7. peptidoglycan
45
Porins
channels for movement of hydrophilic low-molecular weight substances
46
Periplasm:
space located between cytoplasmic and outer membranes ~15 nm wide Contents have gel-like consistency Houses many proteins
47
Cell walls of Archaea
NO peptidoglycan Typically NO outer membrane Variety of chemistries including polysaccharides, proteins, and glycoproteins Pseudomurein Polysaccharide similar to peptidoglycan Composed of N-acetylglucosamine and N-acetyltalosaminuronic acid Found in cell walls of certain methanogenic Archaea Some Archaea lack pseudomurein Array of other polysaccharides and compounds
48
Pseudomurein
Polysaccharide similar to peptidoglycan Composed of N-acetylglucosamine and N-acetyltalosaminuronic acid Found in cell walls of cSome Archaea lack pseudomurein Array of other polysaccharides and compoundsertain methanogenic Archaea
49
S-Layers
Most common cell wall type among Archaea Consist of protein or glycoprotein Paracrystalline structure Interlocking molecules with ordered appearance Variety of symmetries Hexagonal, tetragonal, trimeric, etc.
50
What is this?
S-Layers
51
Capsules and Slime Layers General descriptions: What are they? Why?
Polysaccharide layers May be thick or thin, rigid or flexible Assist in attachment to surfaces Protect against phagocytosis Resist desiccation
52
Slime Layers
Looser matrix does not exclude India ink Loosely attached to cell wall
53
Capsules
Tight matrix excludes India ink Adhere firmly to the cell wall
54
Biofilm
Thick layer of cells (“multicellular”) Exopolysacharies play key role in biofilm development
55
Fimbriae
Filamentous protein structures Enable organisms to: Stick to surfaces Form pellicles Form biofilms
56
Pili
Filamentous protein structures Typically longer than fimbriae Less pili per cell than fimbriae Assist in surface attachment Facilitate genetic exchange during conjugation Type IV pili involved in twitching motility (gliding Can conduct electricity
57
Sporulation
Complex series of events Genetically directed
58
Cell Inculsions
Store reservoirs in cellular inclusions When there is an excess Store for later use Storing in inclusion reduces osmotic stress vs. in cytoplasm
59
Gas Vessicles
Confer buoyancy in planktonic cells Live a floating existence within water column Spindle-shaped, gas-filled structures Hollow yet rigid Made of protein Gas vesicle impermeable to water Vary from few to hundreds per cell Bacteria and Archea, but not in Eukarya
60
Polyphosphates
Accumulations of inorganic phosphate
61
Sulfur globules:
Composed of elemental sulfur Sulfur oxidizers utilize Periplasm
62
Magnetosomes:
magnetic storage inclusions Iron mineral magnetite – Fe3O4 Can provide orientation – magnetotaxis
63
Endospores
Highly differentiated cells resistant to heat, harsh chemicals, and radiation “Dormant” stage of bacterial life cycle Ideal for dispersal via wind, water, or animal gut Only present in some gram-positive bacteria
64
Endospore Structure
Structurally complex Contains dipicolinic acid Enriched in Ca2+ Core contains small acid-soluble proteins (SASPs)
65
Stages in Endospore formation
66
Dormant Cells The scout model
Evolutionary defense mechanism RANDOMLY drives individual bacteria into and out of dormancy Bacterial safe as dormant A tiny fraction will randomly wake up into activity, and unwittingly “scout” the environment Perish or propagate
67
Flagellum
structure that assists in swimming Different arrangements: peritrichous, polar, lophotrichous, amphitrichous (two poles) Helical in shape
68
What are the different Fagella types
A. Polar B. Lophotrichous c. Amphitrichous d. Peritrichous
69
Baterial Flagella
Consists of several components Filament composed of single type of flagellin Move by rotation – rotary motor Energy required for rotation comes from proton motive force ~1000 protons translocated per rotation Gram negative: L ring, P ring, MS ring, C ring Gram positive: P ring, MS ring, C ring
70
Gram ?
Gram Negative
71
How do they decide where to go? Flagella movement in Bacteria?
Bacterial flagella increase or decrease rotational speed in relation to strength of the proton motive force Differences in swimming motions Peritrichously flagellated cells move slowly in a straight line Polarly flagellated cells move more rapidly and typically spin around
72
Tumble turn methods for Petrichously and polarly faalgellated prokaryotes
73
Archael Flagella
Archaeal Flagella Smaller diameter than Bacteria 10-13 nm vs 15-20 nm Lack central channel Great diversity of flagellin proteins Amino acid sequence of flagellin proteins show no phylogentic relationship to Bacterial More similar to type IV pili Powered by ATP instead of protons Flagellin added at base during synthesis
74
Picture an Archaeal Flagella
75
Eukaryote Flagella
A bundle of nine fused pairs of microtubule doublets surrounding two central single microtubules: “9+2” Axoneme Basal body base (kinetosome) is the microtuble organizing center Flagellum encased within cell’s plasma membrane Powered by ATP
76
What is this?
Eukaryote Flagella
77
Gliding Motility
Flagella-independent motility Movement typically occurs along long axis of cell Requires “surface” contact Various mechanisms Excretion of polysaccharide slime Type IV pili Gliding-specific proteins Others unknown PILI PULL
78
Gliding Motility, How it's done Image
79
Taxis
directed movement in response to chemical or physical gradients
80
Chemotaxis
Directed movement in response to chemicals
81
Phototaxis
Directed movement in response to light
82
Aerotaxis
Directed movement in response to oxygen
83
Osmotaxis
Directed movement in response to ionic Strength
84
Hydrotaxis
directed movement in response to water
85
Hydrotaxis
Directed movement in response to water
86
Magnetotaxis
Directed movement in response to earths magnetic field
87
Picture the difference between run and tumble behavior with and without an attractant
88

Microbiology Test 1 (6 decks)

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