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PHA112 > Microbiology 3 > Flashcards

Microbiology 3 Flashcards

1
Q

on a large scale what do bacteria form?

A

colonies

  • aggregates of individual bacteria
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2
Q

what can bacteria take on?

A

different shapes, colours, sizes

  • depends on species
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3
Q

what is the physical appearance of bacteria known as?

A

morphology

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4
Q

what does the size range of bacteria?

A

1-10 micrometres

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5
Q

give the 3 main shapes of bacteria?

A
  • cocci (spheres)
  • bacilli (rod shaped)
  • spiral bacteria
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6
Q

what are monococcus bacteria?

A

single cells

e.g. micrococcus flavus

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7
Q

what are diplococcus bacteria?

A

paired cells

e.g. nisseria gonorrhoeae

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8
Q

what are staphylococci?

A

grouped cells

e.g. staphylococcus aureus

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9
Q

what are streptococci?

A

chained cells

e.g. streptococcus pyogenes

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10
Q

what are tetrads?

A

groups of 4 cocci in the same plane

e.g. micrococcus luteus

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11
Q

what are sarcina?

A

cuboidal arrangements of 8 cocci

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12
Q

what is a bacillus?

A

single rod

e.g. bacillus cereus

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13
Q

what are diplobacilli?

A

two bacilli side by side

e.g. coxiella burnetii

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14
Q

what are streptobacilli?

A

chains of bacilli

e.g. streptobacillus monoliformis (rat bite fever)

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15
Q

what is a spirellum?

A

a rigid spiral gram negative bacterium

e.g. campylobacter jejuni / h.pylori

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16
Q

what is a spirochete?

A

thin, long, more flexible bacterium

e.g. treponema palladium

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17
Q

bacterial cells can adapt … … to environmental changed than eukaryotic cells

A

more readily

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18
Q

what are the structural components of bacterial cells?

A
  • cell wall

- plasma membrane

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19
Q

what are the genetic components of bacterial cells?

A
  • nucleoid

- plasmid

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20
Q

what is the protein production component of bacterial cells?

A

ribosomes

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21
Q

what are the motility components of bacterial cells?

A
  • flagella

- pilli

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22
Q

what are the specialist structures of bacterial cells?

A
  • endopores

- capsules and slime

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23
Q

what is the purpose of a cell wall for bacterial cells?

A
  • provides shape

- protects against osmotic lysis

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24
Q

bacteria can be divided into 2 major groups depending on structure.

what are they?

A
  • gram positive - cells have single plasma membrane

- gram negative - have 2 plasma membranes

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25
Q

what is peptidoglycan?

A

polymer of sugar and amino acids

  • alternating residues of beta-(1,4) linked N- acetylglucosamine (NAG) and N- acetylmuramic acid
  • attached to NAM = chain of 3-5 AA
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26
Q

the peptidoglycan layer lets particles …. through in both gram positive and gram negative

A

< or equal to 2nm

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27
Q

how much of the cell weight is gram positive?

A

90%

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28
Q

how much of the cell weight is gram negative?

A

10%

29
Q

what does the plasma membrane comprise of?

A
  • lipid bilayer
  • proteins
  • lipopolysaccharide (gram neg)
  • retains cytoplasm and separates internal and external enviro
30
Q

what are the properties of the plasma membrane?

A
  • provides support for proteins

- selectively permeable

31
Q

what does the lipid bilayer comprise of?

A
  • amphipathic phospholipids
  • hydrophilic head points out
  • hydrophobic tail points in
  • NO sterols (cholesterol) - pentacyclic hepanoids
32
Q

what are the 2 main types of membrane proteins?

A
  • integral

- peripheral

33
Q

integral proteins?

A
  • 75% membrane proteins
  • tightly attached/stretched across lipid bilayer
  • ion transport
34
Q

peripheral proteins?

A
  • 25% membrane proteins
  • aqueous solubility
  • cholesterol oxidases (depletes eukaryotic cells of cholesterol)
35
Q

what does the lipopolysaccharide (LPS) contribute to?

A

structural integrity of bacterial cells

36
Q

what are the 3 domains that the LPS consists of?

A
  • O antigen
  • core antigen
  • lipid A
37
Q

what can the LPS stimulate?

A

pro-inflammatory immune response

  • small amounts can cause illness
38
Q

what can endotoxemia lead to?

A

septic shock

39
Q

what is LPS highly controlled in?

A

sterile manufacturing

  • limulus amebocyte lysate (LAL)
40
Q

what is the flagella involved in?

A

bacterial motility

41
Q

where the different types of flagella?

A
  • monotrichous (v.cholerae)
  • lophotrichous
  • amphitrichous
  • peritrichous (e.coli)
42
Q

what is the size of flagella?

A

approximately 10 micrometers

  • long compared to bacterial cell
43
Q

what are flagella powered by?

A

H+ / Na+ flow

44
Q

what are flagella involved in?

A

pathogenesis

  • crucial for virulence of v.cholerae
  • flagella propel h.pylori through mucus lining in stomach
45
Q

what are pilli also known as? and where are they mainly found?

A
  • fimbriae

- gram negative bacteria

46
Q

what are the 2 main types of pilli?

A
  • conjugative pilli (allows transfer of DNA between 2 bacteria)
  • type IV pilli (can generate twitching motility)
47
Q

what are capsules and slime layers comprised of?

A
  • polysaccharides

- exact composition varies by species (e.g. D-glutamic acid capsule in B. anthracis)

48
Q

if organised and permanent it is a…

A

capsule

49
Q

if loosely formed it is a…

A

slime layer

50
Q

what are capsules and slime layers not needed for?

A
  • in vitro growth

- have to be induced

51
Q

what are capsules and slime layers useful for?

A
  • attachment to surfaces

- protection from adverse conditions

52
Q

what is the main component of bacterial genetic material?

A

nucleoid

53
Q

properties of nucleoids?

A
  • not membrane bound
  • single chromosome of double stranded DNA
  • DNA highly coiled and wrapped around nucleiod proteins (not same as histones)
54
Q

what is the size of the bacterial genome in comparison to the human genome?

A

0.6-10 Mbp

human genome - 3000Mbp

55
Q

what are plasmids and give their properties?

A

extra chromosomal pieces of DNA

  • can replicate autonomously in host
  • vary in size 1->200Kbp
  • sometimes present in eukaryotic cells
  • can = transferred between cells
56
Q

what are plasmids responsible for?

A
  • antibiotic resistance

- virulence characteristics (pXO1 in B. anthracis)

57
Q

what are the 2 subunits of ribosomes in bacterial cells?

A
  • small 30s

- large 50s

58
Q

what does the size, sequence and structure of bacterial cells make them a target for?

A

antibiotics

59
Q

the ability to form spores exists in some bacterial species.

most notably …

A
  • bacillus spp.

- clostridial spp.

60
Q

what is sporulation triggered by?

A

adverse conditions (lack of nutrients)

  • acts as survival mechanism inc resistance to temp, pH, chemical biocides
  • metabolically inert
61
Q

what human diseases is sporulation important in?

A
  • clostridium difficile in diarrhoea (CDAD)

- anthrax caused by b.anthracis

62
Q

how can bacterial endospores be viewed?

A

using phase contrast microscopy/stained

63
Q

trichomes

A

chains of cells forming long filaments

  • cells remain attached after division
  • cells separate by cross walls (septa)

e.g. cyanobacteria

64
Q

hyphae

A

tube-like filaments which may/may not have septa

  • may form dense mycelial material
  • filamentous fungi

e.g. streptomycetes

65
Q

close spatial and physiological relationships allow what?

A

specialisation

66
Q

what do viral structures comprise of?

A
  • genetic material
  • protein coat
  • receptors
  • lipid envelope (optional)
67
Q

viruses can also infect prokaryotes such as..

A

bacteriophages

68
Q

most bacteriophages (95%) belong to the caudovirales such as…

A
  • myoviridae
  • siphoviridae
  • podoviridae

PHA112 (37 decks)

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