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Microbiology > Review Slides I- 10/16/21 > Flashcards

Review Slides I- 10/16/21 Flashcards

1
Q

Difference between prokaryotes and Eukaryotes (4)

A

Prokaryotes

  • No nuclear membrane
  • No membrane bound organelles
  • No endocytosis (have cell wall)
  • Much smaller
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2
Q

Bacillus

A

Rod shaped

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3
Q

Cocci

A

Round

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4
Q

Gram positive color

A

Purple

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5
Q

Gram negative color

A

Pink

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6
Q

Gram positive cell wall structure

A

Thick peptidoglycan covering with lipoteichoic acid

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7
Q

Gram negative bacteria cell wall

A

Thin peptidoglycan layer with asymmetric outer membrane with lipopolysaccharide, less permeable

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8
Q

Example of endotoxin

A

Lipopolysaccharide, also superantigen

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9
Q

Transpeptidase

A

Enzyme responsible for linking D-Ala and L-Lys during peptidoglycan cross linking

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10
Q

Penicillin structure

A

Mimics D-Ala D-ala

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11
Q

Penicillin mechanism of action

A

Inhibits transpeptidase during bacterial growth, causes cell lysis

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12
Q

Bacterial growth curve stages (4)

A
  1. Lag
  2. Exponential
  3. Stationary
  4. Death
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13
Q

What happens in Exponential stage (4)

A
  • Growth
  • Synthesis of precursors
  • Polymerize macromolecules
  • Produce ATP, reducing power
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14
Q

What happens in stationary stage (7)

A
  • Motility/Chemotaxis
  • Secretion of degradative enzymes
  • Transport of secondary nutrients
  • Intracellular catabolic pathways
  • Genetic competence
  • Sporulation
  • Antibiotic and toxin production
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15
Q

Two forms of RNA pol

A

Holoenzyme and core enzyme

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16
Q

Holoenzyme

A

Binds at the promotor, includes a2,B, B’, sigma

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17
Q

Core enzyme

A

Doing the transcription, Includes a2, B, B’

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18
Q

Transcription initiation

A

Sigma subunit leaves, core enzyme continues on

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19
Q

Where positive regulators bind

A

Upstream of promotor, aids RNA poly in binding to the DNA/transcribing

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20
Q

Repressor mechanism

A

Binds to the promotor, blocks RNA poly from binding

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21
Q

Promotor

A

Where RNA pol binds, -10 to -35 region

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22
Q

Pathogenicity Locus (PaLoc)

A

Organization of toxin genes and their regulatory elements, Tcd locus in C. Diff

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23
Q

Inactive CodY

A

In the absence of nutrients (isoleucine), it is inactive and can’t bind to the promotor region of tcdR to inhibit its transcription

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24
Q

Genes of the tcd PaLoc

A

TcdR (sigma factor), tcdB (Toxin), tcdE (holin), tcdA (toxin), tcdC (sigma factor)

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25
Q

TcdR

A

Sigma factor for the whole PaLoc, increases transcription

26
Q

TcdB

A

Toxin

27
Q

TcdE

A

Holin, allows the toxin to escape bacteria

28
Q

TcdA

A

Toxin

29
Q

TcdC

A

Anti sigma factor, in the presence of nutrients, it binds any existing tcdR protein and inhibits transcription

30
Q

Active CodY

A

Active when bound to Isoleucine (nutrient rich environment) binds to the promotor of tcdR and inhibits transcription

31
Q

Toxin

A

A protein that damages eukaryotic cells

32
Q

Exotoxins

A

Most classical toxins

33
Q

Organization of C. Difficile toxin

A

C terminal receptor binding carb region, middle hydrophobic region, cysteine protease domain (self cleavage), N terminal enzymatically active domain

34
Q

How C. difficile toxin gets into the cell

A

Taken into early endosome after carb recognition, acid environment causes structural change which threads through endosome, self cleavage

35
Q

Mechanism of enzymatically active domain of C. Diff

A

UDP-glycosylation of those proteins (G proteins)

36
Q

Clostridium botulinum

A

Causes botulism, obligate anaerobic, gram-positive spore forming bacillus

37
Q

Botulism hallmarks

A

Flaccid paralysis, intoxication (only take in toxin), rare, antibodies against toxin can alleviate symptoms

38
Q

A-B toxin

A

B subunit recognizes the target cell and triggers RME, mediates membrane insertion

A subunit is enzymatically active, translocated by the B subunit

39
Q

Botulism mechanism of action

A

A protease that prevents acetylcholine release in the peripheral nervous system, cleaves proteins involved in synaptic vesicles fusion, results in flaccid paralysis

40
Q

Clostridium tetani

A

Causes tetanus, spore forming gram positive obligate anaerobe

41
Q

Tetanus hallmarks

A

Spores of C. Tetani in soil can enter wound, germinate, and produce toxin
- Trismus and spastic paralysis

42
Q

Tetanus toxin mechanism of action

A

A-B toxin that targets the CNS, prevents the release of inhibitory neurotransmitters (GABA) that causes spastic paralysis

43
Q

Protein target of both tetanus and botulism

A

Synaptobrevin

44
Q

Targets of only botulism

A

SNAP-25 and syntaxin

45
Q

Cholera hallmarks

A

Vibrio cholarae, gram negative, comma-shaped, facultative anaerobe
Noninvasive, all symptoms are due to a single exotoxin, cholera toxin

46
Q

Cholera toxin properties

A

A1-B5 stoichimetry (A is sitting in a donut hole)

47
Q

Cholera toxin mechanism of action

A

ADP ribosylates the G protein critical to fluid balance, locking it “on”, increases secretion of Cl-, decreases Na+ absorption, leads to mass water secretion

48
Q

Colonized sites (6)

A
  • Nares
  • Oral cavity
  • Skin
  • Small intestine
  • Proximal colon
  • distal colon
49
Q

Maybe colonized sites

A

Stomach

50
Q

Not colonized sites

A

CNS/spinal fluid

Blood

51
Q

Why do we doubt studies with new sites?

A
  • Could be experimental contamination

- Could be dead/killed bacteria

52
Q

How many genes do we carry?

A

Human- 22,000
bacteria- 3,300,000
Over 99% bacteria
(Same amount of cells)

53
Q

Functions of our symbiotic gut microbiome (3)

A
  • Metabolic
  • Immune and structural
  • Protective
54
Q

Metabolic functions of microbiome

A
  • Synthesize vitamins (vitamin K)
  • Harvest maximum energy through digestion (fermentation of complex polysaccharides)
  • Controls epithelial differentiation and proliferation
55
Q

Immune and structural functions of microbiome (4)

A
  • Immuno system development and modulation
  • Induction of IgA antibodies
  • Enhancement of intestinal tight junctions
  • Prevention of intestinal barrier dysfunction
56
Q

Protective functions of gut microbiome (3)

A
  • Competition for niche
  • Competition for nutrients
  • Production of antimicrobial factors
57
Q

Factors that promote symbiosis (4)

A
  • Exercise
  • healthy diet
  • Exposure to diverse microbes
  • breast fed
58
Q

Factors that promote dysbiosis (5)

A
  • Formula fed
  • Over sanitized environment
  • Poor diet
  • sedentary lifestyle
  • Antibiotics
59
Q

Point at which microbiome is fixed

A

~3 years (1000 days)

After that, you can only change the proportions or destroy with abx, can’t introduce new species

60
Q

FGerm free mouse study on obesity

A

From discordant (one obese one thin) man twins, germ free mice receive gut microbiome, mouse that received thin twin stayed thin, mouse that got fat twin microbiome got fat, all things else the same

Microbiology (11 decks)

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