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Microbiology > Lecture 2 > Flashcards

Lecture 2 Flashcards

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Biology 101 flashcards
1
Q

gram positive cell walls contain a thick peptidoglycan layer along with one or both of the following structures that provide elasticity and stability

A
  • wall teichoic acids (WTA)
    • anchored to peptidoglycan
  • lipoteichoic acids (LTA)
    • anchored to cell membrane
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2
Q

wall teichoic acids (WTA) and lipoteichoic acids (LTA) are anchored to what

A
  • WTA: peptidoglycan
  • LTA: cell membrane
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3
Q

WTA and LTA have what two main functions that increase the virulence of gram positive organisms

A
  • adhesins
    • adherence to host cells is the first step in the invasion process
  • inititate endotoxin-like activites when released
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4
Q

acid fast cells contain what structure that keeps the immune system from recognizing them?

A

mycolic acid layer

  • gives organism a waxy coat
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5
Q

acid fast cells contain what structure that are embedded in the mycolic acid layer and allow passage of small hydrophilic molecules

A

tetrameric porins

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6
Q

acid fast organisms should be stained using?

A
  • acid fast stain
    • uses carbol fuchsin (primary stain)
    • methylene blue (counterstain)
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7
Q

what are the clinically important acid fast organisms?

A
  • mycobacterium
  • nocardia
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8
Q

flagellum have what three major components?

A
  • filament
  • hook
  • basal body
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9
Q

filament portion of flagellum contains what antigen?

A

H antigen

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10
Q

function of basal body of flagellum

A

anchors flagellum in the cell wall and cell membrane

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11
Q

function of bacterial pili

A
  • have adhesins that promote adherence to other bacteria or to host cells
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12
Q

what are the two main types of pili

A
  • common pili = fimbriae
  • sex pili
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13
Q

common pili (fimbriae) are composed of subunits. The tips of these subunits contain adhesins, and many of these adhesins are ?

A
  • pilin subunits
  • adhesins are lectins
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14
Q

function of lectins?

A

adhesins that bind to sugars

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15
Q

what is the polysaccharide layer outside the bacterial cell wall called? What antigen is in this structure?

A
  • Glycocalyx
  • K antigen
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16
Q

glycocalyx comes in what two forms?

A
  1. capsule: rigid, closely surrounds cell
  2. slime layer: loose, more diffuse
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17
Q

nucelar region (Nucleoid) of a bacteria contain what structures?

A
  • NO nuclear membrane
  • contains primarily DNA but also RNA and protein
  • most bacteria have one single, circular chromosome
  • some bacteria have plasmids
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18
Q

plasmids encode for information

A
  • ancillary (non-essential)
  • genes that encode Abx resistance, heavy metal resistance, toxins
  • increase virulence
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19
Q

bacteria ribosomes are what? and contain what subunits?

A
  • 70S
  • 30S + 50S
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20
Q

what are inclusions/inclusion bodies?

A

collective term for various granules, vesicles, and vacuoles within cytoplasm

  • function as storage depots
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21
Q

what do volutin granules store

A

storage form of polymers of inorganic polyphosphate

22
Q

what do glycogen granules store

A

polymers of a-D-glucose

23
Q

what do PHB granules store

A

chains of B-hydrobutyric acid

24
Q

describe endospores

A
  • resting stage allowing an organism to survive harsh environmental conditions; often triggered due to nutrient depletion
  • NOT a reproductive function for bacteria
25
Q

endospores contain what that keep it hidden from immune system

A
  • calcium bound to dipicolinic acid
  • keratin spore coat
26
Q

what are clinically relevant genera that produce endospores

A
  • bacillus
  • clostridrium
    • both are gram positive
27
Q

sex pili are present on which types of bacteria

A

gram negative only

28
Q

bacteria replicate via what mechanism

A

binary fission

  • produces two genetically identical cells
29
Q

in a liquid culture, most bacteria have a typical growth curve with what 4 phases

A
  • Lag phase
  • exponential phase
  • stationary phase
  • decline
30
Q

describe measuing bacterial growth using optical density

A
  • more cells in culture -> more absorbance of light
  • measures all cells in culture (viable and non-viable)
31
Q

describe measuring bacterial growth using colony-forming unit

A
  • dilute culture and plate -> each colony from 1 cell
  • measures viable cells
32
Q

lag phase

A
  • no cell division
  • increase in biomass
  • length depends on nutrients available and condition of inoculum
33
Q

log phase (exponential phase)

A
  • exponential growth
  • rapid cell division
  • primary metabolites
  • pathogens produce virulence factors
34
Q

stationary phase

A
  • supplies of energy and nutrients exhausted
  • resources renewed by cell death
  • death = division
  • zero population growth
35
Q

death, decline phase

A
  • insufficient resources for growth
  • exponential cell death
36
Q

first step to determining what an organism is?

A

isolate an organism in pure culture

  • streaking plates with a wire loop
37
Q

differentiate between defined and complex media

A
  • defined media: known quantities of each component, narrower range of growth
  • complex media: some components not chemically defined, broader range of growth
38
Q

enriched media

A
  • complex + growth factors
    • used for growing fastidious organisms
39
Q

selective media

A

select against unwanted organisms

40
Q

differential media

A
  • differentiates between organisms
  • contains components that result in a visible change (color of colony, formation of precipitate)
41
Q

MacConkey agar contains what

A
  • Lactose
  • bile salts and crystal violet inhibit gram +
  • differential and selective
42
Q

chocolate agar contains what?

A

lysed red blood cells (enriched medium)

43
Q

Haemophilus and Neisseria are fastidious organisms and require what to be added to medium

A

Hemin and NAD

44
Q

differentiate between obligate and facultative bacteria

A
  • obligate: limited to a narrow range of a given environmental parameter
  • facultative: capable of surviving in different conditions
45
Q

most pathogenic bacteria survive in what temperature?

A
  • Mesophiles: range 12-42 C, optimum 30-37 C
46
Q

most pathogens exist in what pH

A
  • Neutrophile 5.5-8.5 pH
47
Q

why do obligate/strict anaerobes not survive in oxygenated environments

A

do not have enzymes for ROS produced during metabolism

48
Q

list enzymes that aerobic and facultative bacteria have to counteract ROS

A
  • superoxide dismutase
  • catalase
  • peroxidase
49
Q

capnophiles

A

require high CO2 levels

50
Q

halophiles

A

need high salt

51
Q

osmophiles

A

need high osmolarity/sugar

Microbiology (8 decks)

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