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Infectious Agents > Microbial Structure & Function > Flashcards

Microbial Structure & Function Flashcards

1
Q

What Greek words is the word prokaryotic derived from and their meaning

A 
'Pro' = before
'Karyon' = the nucleus
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2
Q

Can eukaryotes be single celled?

A

Yes e.g. Some yeasts and protists

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3
Q

What are the 4 classes of protist?

A
  • Sporozoa
  • flagellate
  • ciliate
  • amoebae
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4
Q

Is pneumocystis jiroveci a protest or fungi ?

A

Fungi

*originally thought to be a protist

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5
Q

Why are fungi considered as their own kingdom rather than as plants ?

A
  • unique cell envelope (chitin, glucans and mannans)
  • mode of reproduction = budding or fission
  • absence of chlorophyll
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6
Q

Define chemoheterotroph

A

Gains energy from redox reactions of organic compounds

Hetero= cannot make their own food, obtain nutrients via absorption
Chemo = require organic chemicals
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7
Q

Where is chitin found ?

A
  • fungal cell wall

- exoskeleton if Arthropods

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8
Q

What is budding in yeasts ?

A

One or more daughter cells grow as buds until they separate form the mother cell (asexual reproduction)

  • most yeasts
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9
Q

Budding is one type of asexual reproduction in fungi, what is the other?

A

Binary fission - cell grows to a critics, size then splits in two

  • some yeasts
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10
Q

Under what conditions would a fungi reproduce by binary fission?

A

Adverse conditions e.g, scarce nutrients

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11
Q

Define saprotroph

A

Obtain nutrients from dead or decaying matter

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12
Q

What is the mycelium

A

Network of hyphae in moulds

  • form the vegetative body of moulds
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13
Q

Which plant pathogen produces ergotamine as a secondary metabolite?

A

Claviceps purpurea

  • ergot fungus growing on the ears of rye and cereal plants
  • ergotamine narrows blood vessels, so can be used or post partum bleeding and is hallucinogenic
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14
Q

Which fungus produces a carcinogenic secondary metabolite ?

A

Aspergillus flavus - aflatoxin

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15
Q

Which plant pathogen is used to produce quorn?

A

Fusarium graminearum

  • found in cereal grains e,g, wheat and barley - causes ear rot in corn
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16
Q

The causative organisms of potato blight and the Irish potato famine ?

A

Phytophthora infestans

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17
Q

Botrytis cinerea causes which diseases ?

A
  • noble rot of grapes on vine -> distinctive high quality wine
  • grey rot
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18
Q

Define biotroph

A

Organism which feeds on the living tissue of its host

*they depend on the continued functioning if it’s host therefore don’t tend to kill it

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19
Q

What is the term for an organism which aggressively kills its hosts cells and then feeds on the dead and decaying tissue ?

A

Necrotroph

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20
Q

Define commensalism

A

Members of different species living together in close association without much noticeable influence to one another

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21
Q

Define symbiosis

A

The association of dissimilar organisms, usually to their mutual benefit

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22
Q

What are mycorrhizas ?

A

Fungi living in association with the roots of a plant in a symbiotic relationship

*the fungus assists in absorption of water and minerals and protects it from other fungi and nematodes, the fungi receives carbohydrates from the plant

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23
Q

Which gram negative bacillus caused the plague?

A

Yersinia pestis

  • infected fleas which lived in the backs of black rats
  • rat = vector
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24
Q

Examples of small bacteria:

A
  • Bordetella pertussis (0.2x1 micron)
  • Treponema pallidum (0.13x13)
  • Mycoplasma spp. (0.1x0.25) SMALLEST KNOWN ORGANISM THAT CAN GROW OUTSIDE HOST CELLS
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25
Q

Examples of medium bacteria

A
  • bacillus subtilis (0.7x3)
  • E. coli (0.4x3)
  • S. aureus (0.4x0.5)
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26
Q

Examples of large bacteria

A
  • beggiatoa gigantea (5x13)
  • Cyanobacteria (4-5 microns)
  • thiomargarita namibiensis (diameter 750) *LARGEST PROKARYOTE
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27
Q

What are lysogens?

A

Bacteria which have been stably infected with bacteriophage - carrying the virus as a prophage
* bacteriophage DNA integrated into the chromosome of the bacterium

28
Q

Bacteria which retain a crystal violet-iodine complex when treated with acetone or alcohol are said to be what?

A

Gram positive (purple)

29
Q

Name the only biopolymer which contains D-amino acids

A

Peptidoglycan - in bacterial cell walls

30
Q

What is the bacterial plasma membrane made of?

A

Conventional phospholipid bilayer, embedded with proteins

31
Q

What does the outer leaflet of the gram negative of the gram negative outer membrane comprise of?

A

LPS with outer membrane proteins embedded

32
Q

What is lipid A?

A

Endotoxic responsible for gram negative shock

- it is the lipid moiety of LPS

33
Q

What is the appearance of colonies of bacteria which are encapsulated ?

A

Smooth colonies

34
Q

Outline the main virulence factors of bacteria (6)

A
  • encapsulated - resist intracellular killing
  • slime - adherence
  • flagella - motility
  • fimbriae - adherence (gram neg)
  • endospores
  • sex pilus
35
Q

Name the 2 main bacterial genus which produce endospores

A
  • bacillus - aerobic, facultative anaerobes

- clostridium - obligate anaerobes

36
Q

Which lacks a membrane bound nucleus, bacteria or fungi?

A

Bacteria, therefore they are simpler than fungi

37
Q

Which Gran classification retain the crystal violet complex on treatment with acetone/alcohol? What colour are they seen as?

A

Gram positive - purple

38
Q

Which bacteria need counter staining with red dye to be visualised easily ?

A

Gram negative bacteria - appear pink/red

39
Q

Only biopolymer to contain D amino acids ?

A

Peptidoglycan

40
Q

Describe the structure of peptidoglycan including:

  • backbone
  • cross linking
  • amino acids
A
  • Backbone of Alternating units of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
  • NAM units cross linked with oligopeptides
  • contains both D and L amino acids
  • oligopeptides vary between species but all have terminal D-alanine residue
41
Q

Additional polymers in Gram positive envelope as opposed to the Gram negative envelope ?

A

Teichoic and teichuronic acids

42
Q

What does the bacterial cell envelope include ?

A

Inner cell membrane and cell wall

43
Q

How many layers of peptidoglycan do Gram positive and Gram negative have in their cell envelopes?

A
  • positive = 40

- negative = one or two

44
Q

Role of bacterial capsule

A

Protection from phagocytosis

45
Q

For which important disease causing bacteria are capsules a major virulence factor for ?

A

E. coli and S. pneumoniae

46
Q

What year and by who was the gram stain developed ?

A

Christian Gram 1884

47
Q

3 principle layers of gram negative cell envelope ?

A
  • outer membrane
  • peptidoglycan layer
  • cytoplasmic or inner membrane
48
Q

Which molecule is responsible for endotoxic shock caused by septicaemia as a result of gram negative bacterial infection ?

A

LPS

49
Q

Function of the periplasm ?

A

Compartmentalisation allows gram negative bacteria to sequester potentially harmful degradative enzymes e.g. Alkaline phosphates

*thought to be evolutionary precursor of eukaryotic lysosomes

50
Q

Where does the periplasm lie ?

A

Between inner and outer membrane in gram negative bacteria

  • therefore includes the peptidoglycan layers
51
Q

Which stain should be used for mycobacteria and why ?

A

Acid fast stain

- have waxy cell walls

52
Q

Which genus of bacteria are aerobic or facultative anaerobes and produce spores?

A

Genus Bacillus

53
Q

Which genus of bacteria are obligate anaerobes and produce spores?

A

Genus clostridium

54
Q

Family of E. coli ?

A

Enterobacteriaceae

55
Q

What Kingdom is E. coli in ?

A

Eubacteria

56
Q

When and who by was E. coli discovered ?

A

1885

  • Theodor Escherich
  • German bacteriologist
57
Q

What are the 4 classes of macromolecules within bacterial cell ?

A
  • carbohydrates
  • lipids
  • proteins
  • nucleic acid
58
Q

Define chemoautotroph

A

Obtaining nutrition from redox reactions of inorganic compounds

59
Q

Example of alkalinophile

A

Vibrio cholerae

60
Q

Example of acidophile?

A

Lactic acid bacteria

61
Q

Temp range and example of psychrophile ?

A
  • 20 to +10

- pseudomonas antarticus

62
Q

Temp range and example of mesophile ?

A

+20 a +40

- E. coli

63
Q

Temp range and example of thermophile ?

A

+41 to +122

- geobacillus stearothermophilus

64
Q

What factors does H influenzae require for growth on media ?

A

Factors X (haem) and V (NAD, cofactor, can get from lyses RBCs)

65
Q

Describe satellitism between S. auerus and H. influenzae

A

H. influenzae grow bigger near colonies of S. aureus on blood agar as S. aureus provides NAD

66
Q

How can H. influenza and H. parainfluenzae be distinguished in culture ?

A

Influenzae requires X and V, para only requires V

  • culture on nutrient agar and add soaked discs, one with X and V, on with only
  • influenzae will only grow near the one with X and V

Infectious Agents (4 decks)

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