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MD1 > Microbiology > Flashcards

Microbiology Flashcards

1
Q

How big is the average bacteria?

A

1 micrometer

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2
Q

What are the 5 core components of bacteria?

A 
Cytoplasmic membrane 
Cytoplasmic matrix 
Ribosomes
Genome
Cell wall
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3
Q

Where in the body would you find strict anaerobes?

A

The gut

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4
Q

Sometimes blank is used to see whether immune cells can phagocytose?

A

Yeast

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5
Q

If streptococcus divides in one plane, in what arrangement would it be found?

A

Chains

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6
Q

Would you expect to find many gram negative rod bacteria on the skin?

A

No

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7
Q

What is the effect of the bile salts added to MacConkey agar?

A

Bile salts reduce the ability of many bacteria to grow.

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8
Q

On MacConkey agar, what colour is former if the bacteria are lactose fermenters, compared to non fermenters?

A

Colonisation by lactose fermenters results in a deep pink compared to non fermenters which cause yellow colouration.

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9
Q

Name 4 environmental origins of skin/soft tissue pathogens?

A

Soil, surfaces, water, animals.

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10
Q

What colour do gram positive bacteria stain?

A

Purple

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11
Q

What colour do gram negative bacteria stain?

A

Pink

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12
Q

Which type of bacteria has more peptidoglycan in its cell wall?

A

Gram positive

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13
Q

Which type of bacteria has LPS in its cell wall?

A

Gram negative

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14
Q

What has the only genome that could be RNA or DNA?

A

A virus

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15
Q

What is a single celled parasite called?

A

Protozoa

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16
Q

What is a parasite with tissue differentiation called?

A

Metazoa

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17
Q

What component of all cells is highly conserved and used to differentiate the three domains?

A

16S ribosome subunit.

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18
Q

How big is the average animal cell?

A

Approximately 10 micrometers

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19
Q

Why are almost all bacterial genes dominant?

A

They have one circular chromosome. Only one allele per gene.

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20
Q

What component of animal cells is thought to be an endosymbiont?

A

Mitochondria

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21
Q

What are two main functions of bacterial cytoplasmic membrane?

A
  • allows selective interaction with environment (entry of nutrients and elimination of waste)
  • location of metabolic processes such as respiration.
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22
Q

Is the cytoplasmic matrix of bacteria relatively hypotonic or hypertonic?

A

Hypertonic - contains more dissolved material than animals.

23
Q

Does the bacterial nucleoid make replication quicker or slower than animals?

A

Quicker- whilst mRNA is being transcribed, it is also being translated and then destroyed and recycled.

24
Q

Is plasmid replication dependent or independent of chromosome?

A

Independent

25
Q

Name two factors that antibiotics can interfere with?

A

Tight supercoiling of chromosome,

Peptidoglycan- which is found only in bacterial cells.

26
Q

What is a component that can only be found in gram positive walls (that isn’t peptidoglycan)?

A

Teichoic acids (polymers of glycerol or ribitol)

27
Q

What happens if you swallow cholera toxin and why?

A

Short lived cholera - you don’t have the bacteria to continue making the toxin so it doesn’t last.

28
Q

What are 3 features of acid fast bacteria? And name an example of one.

A

Thick, waxy walls.
Consist of peptidoglycan base layer.
Conferred resistance to drying (which contributes to slow uptake of nutrients and therefore slow growth).
Mycobacterium tuberculosis.

29
Q

Is a gram positive cell wall relatively porous?

A

Yes

30
Q

Is a gram negative cell wall relatively porous or impervious?

A

Impervious

31
Q

What is the function of fimbriae (pili)?

A

Adhesion, gene transfer.

32
Q

What features of bacteria allows them to survive

a) short term and
b) long term.

A

Capsules; endospores.

33
Q

What are flagella composed of?

A

Flagellin protein (H antigen)

34
Q

What are thin, long, hollow, helical filaments that bacteria use for locomotion?

A

Flagella

35
Q

What is needed to diagnose a bad case of cholera?

A

Rice water stools with motile bacteria present in wet preparation.

36
Q

Where in he body are bacteria loose in the lumen, and where are they attached to epithelia?

A

Bacteria in lumen of large bowel are mostly unattached from epithelia whereas pathogens in the throat use fimbriae to avoid the swallowing mechanism.

37
Q

How does transfer of plasmids occur in bacteria?

A

Using sex pili

38
Q

On which kind of bacteria are pili usually found?

A

On most gram negative and some gram positive bacteria.

39
Q

What can colonise the small intestine - which is usually mostly free of bacteria? And how do they do it?

A

Enterotoxigenic coli, adhere using adhesive pili (CS1 and CS3)

40
Q

What are bacterial capsules usually made of?

A

Polysaccharide extending from cell surface.

41
Q

What effect do capsules have on the appearance of colonies?

A

Makes them look larger and shiny.

42
Q

What are three functions of a bacterial capsule?

A

Protects against dehydration.

Contributes to virulence. Often protects against phagocytosis.

43
Q

When would bacterial sporulation normally occur?

A

When growth ceases due to a lack of nutrients and/or water.

44
Q

Name 6 features of endospores.

A

Do not replicate.
Impermeable to most stains.
Resistant to: Heat, UV, desiccation, and many chemicals.

45
Q

Which gram positive rods require a special spore stain in order to see them?

A

Clostridium and bacillus

46
Q

Describe the lag phase of the bacterial growth curve.

A

Bacteria adapt to media and start growing- getting longer and bigger.

47
Q

Describe the stationary phase of the bacterial growth curve.

A

As resources become more sparse, growth plateaus. Both growth and death occur simultaneously.

48
Q

What happens on the last phase of a bacterial growth curve?

A

The volume of bacteria decreases as byproducts produced make the media unfavourable.

49
Q

What is metabolism called if oxygen is the final electron acceptor?

A

Aerobic respiration

50
Q

What is metabolism called if an inorganic compound is the final electron acceptor?

A

Anaerobic respiration.

51
Q

What is metabolism called if an organic compound is the final electron acceptor?

A

Fermentation.

52
Q

Name a facultative anaerobes and describe what that means.

A

E. coli, once O2 has been used up, it can switch to anaerobic respiration.

53
Q

What is the name of an organism that grows best in low concentrations of O2?

A

Microaerophile

54
Q

What makes the holes in Swiss cheese?

A

Propionic acid produced by bacteria.

MD1 (4 decks)

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