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microbio > lecture 2&3 > Flashcards

lecture 2&3 Flashcards

1
Q

what does Cooci look like? Bacilli? Vibros, spirilla, spirochetes, and pleomorphic?

A

Vibrios - curved/comma shaped
Spirilla - rigid spiral-shaped
Spirochetes - flexible spiral-shaped
Pleomorphic - organisms that are variable in shape
Cocci - single or arranged spheres
Bacilli - rods

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2
Q

what is the purpose of the different shapes of bacteria?

A

protective mechanisms or aid infection

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3
Q

what are three common bacterial features, and what does each do?

A
  • Cell envelope - plasma membrane and surrounding layers external to it
  • plasma membrane - innermost and selectively permeable membrane and interacts with external environment
  • cell wall - maintain shapes, protects cells from toxic materials and osmotic lysis
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4
Q

Bacterial lipids:

A
  • The plasma membrane - made up of amphipathic lipids
  • Hopaniods - hydrophobic molecules similar to cholesterol (impacts fluidity and shape and forms functional microdomains for protein assembly)
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5
Q

what does the cross-linking mean for peptidoglycan and what are the two types?
- what does it alternate?

A
  • The stands have a helical shape and are crosslinked for strength
  • Direct cross-link - between amino and carboxyl groups
  • Indirect cross link - peptide interbridge may form
  • NAG and NAM - alternating sugars
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6
Q

what color does gram-positive stain?
- what kind of membrane?
- peptidoglycan?
- may contain?

A
  • purple
  • primarily composed of peptidoglycan
  • has teichoic acids
  • periplasm (between the plasma membrane and cell wall) and a few proteins
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7
Q

what are teichoic acids?

A
  • negatively charged
  • These make sure to maintain the cell envelope
  • Protect from environmental substances
  • May bind to host cells to initiate infection
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8
Q

gram negative
- stain?
- peptidoglycan?
- OM?

A
  • pink or red
  • thin layer of peptidoglycan surrounded by an outer-membrane composed of lipids, lipoproteins and lipopolysaccharides
  • no teichoic acids
  • outer membrane outside thin peptidoglycan, connected to peptidoglycan by brauns liporprotins
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9
Q

LPS - lipospolysaccarides

A
  • contribute to a negative charge on the surface
  • Helps stabilize the outer membrane
  • Host defense protection
  • Acts as endotoxin
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10
Q

what are the the component that make the ooutside of the cell wall?

A

capsules
slime layers
S layer
bacterial cytoplasm

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11
Q

what are capsules?

A
  • like a jacket
  • Are well organized and cannot be easily removed from the cell
  • Usually composed of polysaccharides
  • Protective function - resistant to phagocytosis, protects from desiccation, and excludes viruses and detergent
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12
Q

what are slime layers?

A
  • Similar to capsules but they diffuse, unorganised, and easily removed
  • May facilitate motility
  • Cheap version (like vasleine instead of jacket)
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13
Q

S (surface layer)

A
  • Regularly structures self-assembling layers of protein or glycoprotein
  • Protect from ion/pH fluctuations, osmotic stress, enzymes, predation, host defense - these are only in cells with extreme environments
  • Maintains shape and rigidity
  • Promotes adhesion to surface
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14
Q

intracytoplasmic membranes

A
  • plasma membrane in-foldings
  • observed in photosynthetic bacteria and high respiratory activity
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15
Q

bacterial cytoskelton

A
  • Protein filaments that participate in cell division, localize proteins, and maintain cell shape
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16
Q

gas vacuoles

A

Involved in bacterial movement
Provide buoyancy to aquatic bacteria
Made of aggregates of hollow, cylindrical gas vesicles

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17
Q

ribsomes?

A

Complex protein/RNA structure that have Sites of protein synthesis ( 70s)

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18
Q

Nucleoid

A

Usually not membrane-bound
- Usually 1 closed circular ds DNA molecule/chromosome
- supercoiling and nucliode proteins aid in folding and structures

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19
Q

plasmid

A

Small, closed, circular, independent DNA molecules
Carry genes that can confer a selective advantage in some situations

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20
Q

what are the three external structures? purpose?

A
  • fuction in protection, attachment to surfaces , HGT, cell movement
  • fimbriae/pili
  • sex pilli
  • flagella
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21
Q

what are fimbira/pili?

A

Short thin hair-like, protein appendages
Can mediate attachment to surfaces, motility, and DNA uptake

22
Q

sex pili?

A

Longer, thicker, less numerous
Required for conjugation
More defined hollow and produces genetic variation

23
Q

Flagella
function and what it looks like?

A
  • Threadlike, locomotor appendage extending outward from the plasma membrane and cell wall
  • motility, attachment to surface, virulence factor (causes disease)
24
Q

what are the three parts of the bacterial flagella?

A

1.) filament /flagellum - extends from cell surface to top
2.) Hook - short flexible segment
3.) Basal body - embedded in cell envelope

25
Q

what is the two-part motor-producing technique?

A
  • Rotor - moving parts, C-ring ring interact with stators and connects to the rod
  • Stator- stationary parts, capture PMF through the membrane to generate torque and drive rotation
26
Q

what are two ways that flagella can move?

A
  • rotates like a propeller
    CCW rotation = forward movement
    CW disrupts run = tumble
27
Q

how can flagella move?

A
  • chemotaxis: movement towards a chemical attraction or away from chemical repellant
  • Chemoreceptors transmit signals throughout the chemosensing system - detect external signals and determine whether it should run or tumble
28
Q

swarming ?

A
  • long collective run togetehr (lot together)
  • Cells move faster than swimmers and have increased resistance to antibiotics
29
Q

what are the three ways that a bacteria will move without using a flagella?

A

1.) twitching - short, jerky movement (cells are in contact with each other and surface)
2.) gliding - smooth movement w/o appendage and slime can help with movement
3.) spirochete motility - flagella is on the inside and windling around cell (flexing and spinning movement)

30
Q

what is a survival stratgey made by a bacteria?

A
  • using endospores in response to nutrient depletion
  • which are resistant to envionrmnetal changes
31
Q

how does archaea cell envelope differ from bacteria?

A
  • some lack cell walls
  • The slime layer is used to mediate cell-to-cell interactions
  • s-layer is standard used
32
Q

The common shape of archaea?

A

-cocci and rod shape

33
Q

what does an archaea membrane look like?

A
  • unique lipids - that are branched chains of hydrocarbons attached to a glycerol by ether linkage
34
Q

what is the difference between archea and bacterias cytoplasm?

A
  • A ribosomes have different nuc sequences so which means the protein composition is different (makes them unaffected by antibiotics attacking ribosomes)
  • more similar to Euk
35
Q

what are the two types of pilli? archaea

A
  • cannulae - hollow tube structure (how daughter cells are connected to each other)
  • hami - looks like a grappling hook (biofilm)
36
Q

three characteristics of Archaea flagella?

A
  • thinner than bacteria - not hollow
  • powered by ATP hydrolysis
  • direction moves the cell forward or backward
37
Q

what is EUK plasma membrane made up of?

A

sphingolipids
sterols
phospholipids (hydrophobic fatty acids)

38
Q

Two types of euk? charachteristics?

A
  • protist and fungi
  • common in ecosystems
  • adapts
  • larger than A and B
  • major human pathogen
39
Q

EUK
cytoskeleton (3 types of filaments)

A
  • helps organize cytoplasm
  • cell shape/motor proteins associated with filaments that guide cell movements
    1. actin - small (helps shape)
    2. microtubules - thin (spindles)
    3. intermediate - flexible and structural
40
Q

EUK flagella and cillia

A
  • long whiplike and move in an undulating fashion
  • short hair-like structures and beat with 2 phases
41
Q

viron?
nucleocapsid

A
  • mature virus particles
  • composed of nucleic acid (DNA or RNA) and a protein coat (capsid)
42
Q

2 broad types of virus?

A
  1. non-evloped (naked)
  2. enveloped - has a lipid membrane
43
Q

viral envelope?

A
  • a flexible membraneous layer of lipids and carbs
  • can have spikes or peplomers on their surface
  • can be used to identify a virus
44
Q

what are the five steps of viral multiplcation?

A

1.) attachment
2.) entry
3.) synthesis
4.) assembly
5.) viron release

45
Q

how does a virus attach and enter?

A
  • ligand attaches to host cell receptor (determines host prefrence)
  • virus genome enters
46
Q

three methods used to release DNA?

A
  • fusion of biral envelope with host cells plasma membrane
  • endocytosis
  • release of nucleic acid
47
Q

what are the two ways virons can be released?

A
  • host cell lysis (non-enveloped)
  • relase by budding (enveloped)
48
Q

virulent phage vs temperate phage

A
  • v - has one reproductive choice (multiplies upon entering and released from host by lyses)
  • T - two reproductive options (reproduces lytically like virulent and will remain in host cell without destroying it)
49
Q

lysogeny

A
  • relationship between temperate phage and host
  • prophage form of the virus that remains within host until unfavorable conditions and will convert into lytic where it will burst out of cell
50
Q

how can viruses by cultivated?

A
  • viruses can not be cultured
  • plaque-forming units (lytic cycle)
51
Q

one step growth curves

A

1.) inoculation - virus binds (decrease)
2.) Eclipse - virion penetrates cells (plateau)
3.) Burst - host cell releases many viral particles (increase)
4.) Burst size - number of virions released per bacterium (plateau)

microbio (5 decks)

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