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Microbio Quiz 1 JXC > 03-18 Bacterial Structure and Function > Flashcards

03-18 Bacterial Structure and Function Flashcards

1
Q

Who discovered bacteria? When?

A

Antony van Leeuwenhoek in the 1600s

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2
Q

cocci

A

round bacteria

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3
Q

bacilli

A

rod-shaped bacteria

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4
Q

What color do Gram(+) bact stain?

A

violet

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5
Q

What color do Gram(-) bact stain?

A

red

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6
Q

What are the original Koch’s Postulates?

A
  1. find bact in all cases of the dz
  2. grow pure culture of it
  3. reproduce dz by injected subject w/ pure culture
  4. re-isolate same bugger
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7
Q

What are Koch’s Molecular Postulates?

A
  1. phenotype being investigated is assoc’d significantly more often with a pathogenic organism than w/ non-path strain/member
  2. inactivating the gene decreases virulence
  3. replacing w/ w.t. gene returns pathogenicity
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8
Q

What are the classes of microorganisms? Which are pathogens? Which photosynthesize? Which have cell wall?

A

algae - not path; all photosynth; have wall
fungi - can be path; no photo; have wall
protozoa - can be path; no photo; no wall
bacteria - can be path; few are photo; all (but one) have wall

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9
Q

higher vs. lower microorganisms

A 
higher = euk = algae, fungi and protozoa
lower = prok = bacteria
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10
Q

Compare/contrast nucleic acids in proks vs. euks.

A

BOTH - DNA in chromosomes
Euks - several, linear chromosomes inside a nuclear envelope
Proks - single, circ chromosomes just free-ballin’ it in the cytosol

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11
Q

Compare/contrast cell mov’t proks vs. euks.

A

Euks: cytosolic streaming/amoeboid mov’t; flagella of MTs in 9:2 doublet arrangement
Proks: no cytosolic streaming/amoeboid mov’t b/c there cytosol is so viscous w/ ribosomes; do have flaggela not from MTs but rather of flaggelin and not coated by the membrane

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12
Q

Compare/contrast cell wall material in proks vs. euks

A

Euks - cellulose (plants/algae) or chitin (fungi)

Proks - peptidoglycan w/ muramic acid, D-a.a.’s and other unusual a.a.’s

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13
Q

Are archea infectious?

A

No, not that we know of.

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14
Q

Compare and contrast RNA handling proks vs. euks.

A

euks - pre-mRNA made in nucleus, spliced, exported to cytosol and transcribed
proks - no nucleus, no splicing, new mRNA starts get translate before it is even completely processed

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15
Q

What is the size range of most bacteria of medical interest?

A

most are ~1 micrometer (µm) = 10^-6; smallest (mycoplasma at 0.175µm) overlaps with largest of viruses (pox fam at .250µm)

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16
Q

What’s up with spirochetes?

A

They are in a separate phyla and lack a rigid cell wall

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17
Q

What are the medically-relevant patterns of aggregates caused by successive division w/o full separation of cells?

A
  • this occurs most commonly with cocci

- create filaments which can form chains (steptococci) or clusters (staphylococci)

18
Q

What is an example of a bacilli that forms rods?

A

Corynebacterium diphtheriae - ends stick together when dividing end up looking link chinese characters

19
Q

Bacterial cytoplasmic membrane

A

similar composition: 20-30% lipid & 60% prot

  • contains oxidative enzymes for oxid. phosphorylation (acts like inner membrane of a mito)
  • has cell wall synth prots
  • has active transporters to uptake specific nutrients that are low in conc in bact’s dilute enviro
  • has transporters to secrete
20
Q

What is the bacterial “equivalent” of a nucleus?

A

Bact has no true membrane-bound nucleus; has nucleoid instead which is name for region of the circular DNA

21
Q

bacterial ribosomes

A

smaller (70S vs. 80S) and susceptible to antibiotics that do not affect euk ribos

22
Q

Cyotplasmic granules

A
  • visible on microscopy (EM?)
  • contain lipid or glycogen
  • can also contain metachromatic phosphate (e.g. in diptheria, helps ID this bact)
23
Q

Describe the components and structure of the cell wall.

A

Cell wall is made of up strings of NAG (N-acetyl-glucosamine) and NAM (N-acetyl-muramic acid) which have tetrapeptide side chains that vary among species. These glycosides (NAG and NAM) are held together by glycosidic linkages.

The strings are “cross-linked” by peptide bonds created between a.a.’s on NAM’s tetrapeptide side chains.

24
Q

Where is lysozyme produced? Mechanism?

A
  • found in tears and other bodily fluids

- breaks glycosidic linkage between NAG and NAM—>digests cell wall of some bacteria (i.e. anti-bact agent)

25
Q

Are Gram + or Gram - more susceptible to disinfectants and antibiotics?

A

Gram +

26
Q

Gram (+) vs. Gram (-)

A

Gram (+):

  • thicker peptidoglycan cell wall
  • no outer membrane
  • no periplasmic spcae
  • some Gram(+)s’ have cell walls also have teichoic acid (polysacc of ribitol phosph. or glycerol phosph) that are often antigenic
  • more susceptible to anti-microbials

Gram (-):

  • thinner peptidoglycan cell wall
  • has 2nd, outer lipid bilayer
  • has periplasmic space
  • 2nd memb. covered in LPS (a.k.a. endotoxin)
  • less susceptible to anti-microbials
27
Q

Lipid A

A

component of LPS imbedded in the OM (outer memb.)

28
Q

porins

A

transmembrane pore proteins in the OM of Gram (-) bact; small molecules only (many antibiotics, e.g. vanco, too big)

29
Q

LPS components

A

polysacc-confersantigenic specificity; component that sticks out; outermost part is O-antigen
Lipid A-confers toxicity; component imbedded in the OM (outer memb.)

30
Q

O antigen f(x)? Why?

A

O antigen is oligosaccharide at the distal end of the LPS whose sugar sequence confers antigenic specificity to Gram (-) bacteria because they predominate the cell’s surface

31
Q

Degradative enzymes? How diff in Gram (+) vs. Gram (-)?

A

Degradative enzymes can break down large nutrients in external enviro (e.g. polysacchs or proteins) and also antibiotics (e.g. penicilinase)

  • Gram (+) secrete into external environment or tether them to their out cell wall
  • Gram (-) contain these in their special periplasmic space
32
Q

Gram Stain Procedure

A 
1. Crystal violet (1 min)
WASH
2. Iodine to form complex w/ CV (1 min)
WASH
3. Alcohol-based decolorizer (30-60 secs)
WASH
4. Safranin counterstain (1 min)
WASH
BLOT DRY
33
Q

capsule

A

many bact don’t have but those that do use this “loose slime” polysaccharide to resist phagocytosis
-antibodies are made to target this and vaccines sometimes contain capsules/capsular components

34
Q

bacterial flagella components

A

made of flagellins in helical formation with open pore (as opposed to eukaryotic MT-based flagella)

35
Q

bacterial flagella f(x)

A

act like propeller; almost all motile bacteria have flagella

36
Q

flagella arrangements

A

polar flagella - only on one side

peritrichous flagella - all around cell

37
Q

pili and fimbriae; name specific types

A

basically same, just different size

  • hollow tubes of protein
  • sex pili - hold two bacteria together during conjugation
  • F pili - the bacterial penis
  • Type IV pili - allow bacteria to move around once bound to surface of a cell; aids in colony formation
38
Q

Which species make spores?

A

Those of genera Bacillus and Clostridia

-Examples: Bacillus anthracis and Clostridium tetani

39
Q

When are spores created?

A

In times of nutrient deprivation

40
Q

Chemotaxis mechanism

A
  • bacteria employ chemoreceptive sensors in the membrane to control a phospho-cascade that in turn controls the mov’t of flagella
  • when chemo-attracted: flagella rotate counter-clockwise —>str8 forward mov’t
  • when chemo-repelled: flagella rotate clockwise and therefore tumble in place

Microbio Quiz 1 JXC (2 decks)

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