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Microbial Structure & Function Flashcards

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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
Examples of medium bacteria
- bacillus subtilis (0.7x3) - E. coli (0.4x3) - S. aureus (0.4x0.5)
26
Examples of large bacteria
- beggiatoa gigantea (5x13) - Cyanobacteria (4-5 microns) - thiomargarita namibiensis (diameter 750) *LARGEST PROKARYOTE
27
What are lysogens?
Bacteria which have been stably infected with bacteriophage - carrying the virus as a prophage * bacteriophage DNA integrated into the chromosome of the bacterium
28
Bacteria which retain a crystal violet-iodine complex when treated with acetone or alcohol are said to be what?
Gram positive (purple)
29
Name the only biopolymer which contains D-amino acids
Peptidoglycan - in bacterial cell walls
30
What is the bacterial plasma membrane made of?
Conventional phospholipid bilayer, embedded with proteins
31
What does the outer leaflet of the gram negative of the gram negative outer membrane comprise of?
LPS with outer membrane proteins embedded
32
What is lipid A?
Endotoxic responsible for gram negative shock | - it is the lipid moiety of LPS
33
What is the appearance of colonies of bacteria which are encapsulated ?
Smooth colonies
34
Outline the main virulence factors of bacteria (6)
- encapsulated - resist intracellular killing - slime - adherence - flagella - motility - fimbriae - adherence (gram neg) - endospores - sex pilus
35
Name the 2 main bacterial genus which produce endospores
- bacillus - aerobic, facultative anaerobes | - clostridium - obligate anaerobes
36
Which lacks a membrane bound nucleus, bacteria or fungi?
Bacteria, therefore they are simpler than fungi
37
Which Gran classification retain the crystal violet complex on treatment with acetone/alcohol? What colour are they seen as?
Gram positive - purple
38
Which bacteria need counter staining with red dye to be visualised easily ?
Gram negative bacteria - appear pink/red
39
Only biopolymer to contain D amino acids ?
Peptidoglycan
40
Describe the structure of peptidoglycan including: - backbone - cross linking - amino acids
- 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
Additional polymers in Gram positive envelope as opposed to the Gram negative envelope ?
Teichoic and teichuronic acids
42
What does the bacterial cell envelope include ?
Inner cell membrane and cell wall
43
How many layers of peptidoglycan do Gram positive and Gram negative have in their cell envelopes?
- positive = 40 | - negative = one or two
44
Role of bacterial capsule
Protection from phagocytosis
45
For which important disease causing bacteria are capsules a major virulence factor for ?
E. coli and S. pneumoniae
46
What year and by who was the gram stain developed ?
Christian Gram 1884
47
3 principle layers of gram negative cell envelope ?
- outer membrane - peptidoglycan layer - cytoplasmic or inner membrane
48
Which molecule is responsible for endotoxic shock caused by septicaemia as a result of gram negative bacterial infection ?
LPS
49
Function of the periplasm ?
Compartmentalisation allows gram negative bacteria to sequester potentially harmful degradative enzymes e.g. Alkaline phosphates *thought to be evolutionary precursor of eukaryotic lysosomes
50
Where does the periplasm lie ?
Between inner and outer membrane in gram negative bacteria - therefore includes the peptidoglycan layers
51
Which stain should be used for mycobacteria and why ?
Acid fast stain | - have waxy cell walls
52
Which genus of bacteria are aerobic or facultative anaerobes and produce spores?
Genus Bacillus
53
Which genus of bacteria are obligate anaerobes and produce spores?
Genus clostridium
54
Family of E. coli ?
Enterobacteriaceae
55
What Kingdom is E. coli in ?
Eubacteria
56
When and who by was E. coli discovered ?
1885 - Theodor Escherich - German bacteriologist
57
What are the 4 classes of macromolecules within bacterial cell ?
- carbohydrates - lipids - proteins - nucleic acid
58
Define chemoautotroph
Obtaining nutrition from redox reactions of inorganic compounds
59
Example of alkalinophile
Vibrio cholerae
60
Example of acidophile?
Lactic acid bacteria
61
Temp range and example of psychrophile ?
- 20 to +10 | - pseudomonas antarticus
62
Temp range and example of mesophile ?
+20 a +40 | - E. coli
63
Temp range and example of thermophile ?
+41 to +122 | - geobacillus stearothermophilus
64
What factors does H influenzae require for growth on media ?
Factors X (haem) and V (NAD, cofactor, can get from lyses RBCs)
65
Describe satellitism between S. auerus and H. influenzae
H. influenzae grow bigger near colonies of S. aureus on blood agar as S. aureus provides NAD
66
How can H. influenza and H. parainfluenzae be distinguished in culture ?
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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