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[Y1] Introductory Microbiology > Prokaryotic microbes > Flashcards

Prokaryotic microbes Flashcards

1
Q

state 3 key features of prokaryotic cells?

A
  • no define nucleus
  • no membrane bound organelles
  • 70S ribosomes (50S + 30S)
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2
Q

how do prokaryotic cells have a diverse metabolism?

A

enzymes located in cell membrane and cytoplasm

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3
Q

where are the electron transport chain components found?

A

in the plasma membrane

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4
Q

how do prokaryotic cells replicate?

A

only able to replicate asexually (most common is binary fission)

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5
Q

what are the 5 phases of growth in batch culture?

A
  • lag phase (cell synthesizing new components)
  • exponential phase (rate of growth and division is constant and maximal)
  • stationary phase (active cells stop reproducing or reproductive rate is balanced by death rate)
  • death phase
  • long-term stationary phase
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6
Q

give one method used to monitor the cell number

A

Measuring cell mass:
- Measure the optical density of the bacterial culture
- A spectrophotometer is used to pass light of a specific wavelength (~600nm) through microbial suspension
- The higher the cell density, the more light scattered by bacterial cells, less light is transmitted to the detector

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7
Q

how can you count the number of cells?

A
  • Take sample of bacterial culture at each time point
  • Make dilution series and plate out on agar plates
  • Incubate overnight – single cells will grow to form visible colonies on plate
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8
Q

what 3 things do you describe when describing colony morphologies?

A
  • form
  • elevation
  • margin
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9
Q

where do phototrophs get there energy from?

A

sunlight

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10
Q

where do chemotrophs get there energy from?

A

chemicals (inorganic and/or organic chemicals)

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11
Q

where do organotrophs gain electrons from?

A

organic compounds

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12
Q

where do lithotrophs gain electrons from?

A

inorganic compounds

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13
Q

where do autotrophs get there carbon from?

A

use CO2 to make carbon compounds (primary producers)

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14
Q

where do heterotrophs get there carbon from?

A

use organic compounds from their environment

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15
Q

define niche

A

set of environmental conditions in which a species of microbe can replicate

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16
Q

what 7 conditions determin where a microbe can live?

A
  • Nutrient availability
  • Oxygen concentration
  • Temperature
  • pH
  • Light intensity
  • Radiation
  • Solute concentration (osmolarity) & water activity
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17
Q

what are obligated aerobes?

A

requires O2

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18
Q

what are anaerobes?

A

grows in the absence of O2

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19
Q

what are obligated anaerobes?

A

usually killed in the presence of O2

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20
Q

what are microaerophile?

A

requires 2-10% O2

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21
Q

what are facilitated anaeobes?

A

do not require O2 but grow better in its presence

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22
Q

what is temperature range for psychrophiles?

A

0-20 oC

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23
Q

what is the temperature range for psychrotrophs?

A

0-35 oC

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24
Q

what is the temperature range for mesophiles?

A

20-45 oC

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25
Q

what is the temerature range for thermophiles?

A

55-85 oC

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26
Q

what is the temperature range for hyperthermophiles?

A

85-113 oC

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27
Q

where do extremophiles grow?

A

under harsh conditions that would kill most other organisms

28
Q

what are the 5 bacteria cell shapes?

A
  • rod (bacilli)
  • spherical (cocci)
  • spiral (spirilla)
  • corkscrew (spirochaetes)
  • comma (vibrios)
29
Q

what are the 4 arrangements of bacterial cells?

A
  • chain of cocci
  • pair of cocci (diplococci)
  • cluster of cocci
  • chain of bacilli
30
Q

what are the 8 components to a bacterial cells structure? functions?

A
  • capsule (resistance to phagocytes)
  • ribosomes (protein synthesis)
  • cell wall (protection from osmotic stress, maintains shape)
  • cell membrane (selectively permiable barrier)
  • nucleoid (location of genetic material)
  • fimbriae attached to surface, twitching)
  • chromosomes (DNA)
  • flagellum (swimming and swarming motility)
31
Q

how is the DNA found in the nucleoid?

A

Usually 1 closed circular, double-stranded DNA molecule

32
Q

what aid in folding the chromosomes?

A

Supercoiling and nucleoid proteins (different from histones) aid in folding

33
Q

where is extrachromosomal DNA found?

A

found in bacteria, archaea, some fungi

34
Q

what is peptidoglycan?

A

a substance forming the cell walls of many bacteria, consisting of glycosaminoglycan chains interlinked with short peptides.

35
Q

what are the 3 functions of peptidoglycan?

A
  • helps protect cell from osmotic lysis and toxic materials
  • may contribute to pathogenicity
  • rigid structure lying just outside the cell plasma membrane
36
Q

what is the structure of peptidoglycan?

A
  • Mesh-like polymer of identical subunits forming long strands
  • two alternating sugars:
    - N-acetylglucosamine (NAG)
    - N- acetylmuramic acid (NAM)
  • Pentapeptide -alternating D- and L- amino acids
37
Q

what is a gram positive cell wall comprised of?

A
  • Composed primarily of peptidoglycan – thick layer
  • Some Gram-positive bacteria have layer of proteins on surface of peptidoglycan
38
Q

what is a grram negative cell wall comprised of?

A
  • Unusual and more complex
  • Consist of a thin layer of peptidoglycan surrounded by an outer membrane
    - Outer membrane composed of lipids, lipoproteins, and lipopolysaccharide (LPS)(No teichoic acids)
    - OM acts as a selective permeable barrier
39
Q

what 3 things does LPS (lipopolysaccharide) consist of?

A
  • lipid A
  • core polysaccharide
  • O side chain (O antigen)
40
Q

where is LPS found?

A
  • Lipid A embedded in outer membrane (OM)
  • LPS is unique to bacterial OM (Gram –ve)
41
Q

what are 6 functions of LPS?

A
  • Contributes to negative charge on cell surface
  • Host defense protection (O antigen)
  • Helps stabilize OM structure
  • Attachment to surfaces and biofilm formation
  • Creates a permeability barrier
  • Endotoxin/ pyrogenic (lipid A), can lead to septic shock
42
Q

why do gram negative microbes have a selectively permeable membrane?

A

due to presence of porin proteins and transporter proteins

43
Q

what is the capsule?

A
  • Gel-like substance - usually composed of polysaccharides
  • Well organized and not easily removed from cell
  • Visible in light microscope (with capsule stain)
44
Q

what are 3 potective advantages to the capsule?

A
  • resistant to phagocytosis
  • protect from desiccation
  • exclude viruses and detergents
45
Q

what are the 5 functions of the S layer?

A
  • protect from ion and pH fluctuations, osmotic stress, enzymes, and predation
  • maintains shape and rigidity
  • promotes adhesion to surfaces
  • protects from host defenses
  • potential use in nanotechnology
46
Q

what are the 2 functions of flagella?

A
  • motility and swarming behavior
  • may be virulence factors
47
Q

what are the 5 possible patterns of flagellation?

A
  • monotrichous: one flagellum
  • polar flagellum: flagellum at end of cell
  • amphitrichous: one flagellum at each end of cell
  • lophotrichous: cluster of flagella at one or both ends
  • peritrichous: spread over entire surface of cell
48
Q

state 3 things about flagellar synthesis

A
  • Complex process involving many genes/gene products
  • New flagellin molecules transported through the hollow filament using Type III-like secretion system
  • Filament subunits self-assemble with help of filament cap at tip, not base
49
Q

what is chemotaxis?

A

the movement of an organism or entity in response to a chemical stimulus

50
Q

what are fimbriae and pili?
what are they made from?
how are they assembled?

A
  • Thin thread-like appendages that help bacteria to attach to surfaces, host cells, each other
  • Made from protein subunits
  • Assembled from base rather than from the tip
51
Q

what is conjunction?

A

type of horizontal gene transfer

52
Q

what is a biofilm?

A

Community of microbes firmly attached to a surface with the aid of extracellular polymeric substance (EPS) matrix

53
Q

what is heterogenity in biofilms?

A

differences in metabolic activity and locations of microbes

54
Q

what are endospores?

A
  • Dormant, non-growing structures that contain a copy of genome
  • Highly resistant to environmental stress – survival strategy
55
Q

what do archaea have in common with eukarya?

A

Aspects of 16S rRNA sequence, histones, some proteins involved in transcription, translation

56
Q

what do archaea have in common with bacteria?

A
  • 70S ribosomes
  • cell structure
    - binary division
    - some genes for metabolism and transport
57
Q

what are 3 characteristic that are unique to archaea?

A
  • cell membrane composition
  • capable of methanogenesis
  • no known pathogens
58
Q

give 4 archaea cell shapes

A
  • cocci
  • rod-shaped
  • flat squares
  • branched
59
Q

what is the smallest and largest archaea that have been observed?

A
  • Smallest observed is 0.2 μm in diameter
  • Largest (so far) is a multicellular form that can reach 30 mm in length!
60
Q

state 4 things about archaea membranes

A
  • Lack peptidoglycan
  • More diverse than in bacteria
  • Most common cell wall is S layer
  • Only Ignicoccus, thus far identified, has outer membrane
61
Q

explain Escherichia coli

A

Gram negative rods, peritrichous flagella, facultative anaerobe, many strains are commensal, some are pathogenic

62
Q

explain Bacillius cereus

A

Gram positive rods, peritrichous flagella, facultative anaerobe, produces endospores and toxins, can cause food poisoning

63
Q

explain Staphylococcus aureus

A

Gram positive cocci in clusters, facultative anaerobe, commensal and pathogenic strains

64
Q

explain Methanosarcina rumen

A

Irregular cell shape, anaerobic, non-motile methanogenic, lives in rumen of ruminant animals

65
Q

explain Pyrococcus furiosus

A

cocci with glycoprotein S-layer and lophotrichous flagella, hyperthermophile, inhabits hydrothermal vents

[Y1] Introductory Microbiology (8 decks)

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