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Micro > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

What mechanism do bacteria use for uptake?

A

Rocker-switch mechanism

No endocytosis

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2
Q

What system do bacteria use to transport sugars?

A 
Phosphotransferase system (PTS)
If glucose is low, somethign stays phosphorylated, cAMP is produced, alternate carbon sources are used
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3
Q

What are energy sources for rocker-switch mechanism?

A

Membrane potential
Gradient of another solute
ATP hydrolysis

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4
Q

Type I SecMech

A 
3 linked proteins form pore through IM, peri, OM
ATP powers secretion
E. coli hemolysin
Pseudomonas proteases
Pasturella leukotoxin
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5
Q

Type II SecMech

A 
Sec B recognizes leader peptide
Sec A is ATPase
SecYEG is translocon
Periplasmic leader protease 
Specific or semi-specific OM porin
MOST SECRETED PROTEINS IN BACTERIA AND MITOCHONDRIA USE THIS MECHANISM
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6
Q

Type III SecMech

A 
Virulence secretory pathway
One step mechanism
Shigella (Ipas)
Salmonella (Sips)
Yersinia (Yops)
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7
Q

Type IV SecMech

A 
Transport DNA and proteins
Two paradigm systems
1. Agrobacterium tumifaciens VirB/TraF
2. Dot/Icm sytstem in many pathogens
a. Legionella pneumophila
b. Helicobacter pylori
c. Bordetella pertussis
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8
Q

Type V SecMech

A

Autosecretion
Sec B leader on N term through IM
Beta domain on C term spontaneously forms channel through OM
Brucella, E. Coli and others

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9
Q

Type VI SecMech

A

Genes usually located in pathogenicity islands
Structurally similar to bacteriophage tail fiber
Very common

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10
Q

What forms peptidoglycan backbone

A

N-acetylglucosamine
N-acetylmuramic acid
Linked beta 1-4

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11
Q

Which type of bacteria has pentapeptide cross bridge of peptidoglycan?

A

GramPos

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12
Q

What is the pentapeptide side chain added to?

A

UDP N-acetylmuramic acid

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13
Q

What is the MurNAc with pentapeptide added to?

A

Bactoprenol

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14
Q

What happens after MurNAc PP is added bactoprenol?

A

Flips to other side of membrane when BP is phosphorylated. It is then added into a hole in the membrane. Finally crosslinking occurs. BP is dephosphorylated and it flips back in

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15
Q

What blocks UDP addition to MurNAc?

A

Fosfomycin

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16
Q

What inhibits flipping of bactoprenol?

A

Bacitracin

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17
Q

What CLASS blocks transpeptidases?

A

Beta-lactams

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18
Q

What blocks transglycosidase?

A

Glycopeptides

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19
Q

What are the special wall components of GramPos?

A

Teichoic acid (Mg+ reserve, phosphate)
Teichuronic acid
Lipoteichoic acid

20
Q

What is one function of lipoteichoic acid?

A

Links PG to membrane

21
Q

What are holes in the OM?

A

Porins (three proteins)
Non-Allow MW less than 600
semi, specific

22
Q

What links OM to PG layer?

A

Lipoprotein (Brauns protein)

Linked to DAP in PG

23
Q

What is another name for LPS?

A

Endotoxin

24
Q

What binds LPS?

A

LBP after the bacteria has been lysed
LBP then binds to CD14 and TLR4
Induces secretion of lymphokines

25
Q

What are major effects of lymphokines?

A

Increase synthesis of WBC

Increase capillary permeability

26
Q

What is the repeating unit in LPS

A

O-antigen

27
Q

Why is LOS more virulent than LPS?

A

Resemble mammalian sphingolipids and evade host defense

28
Q

How is LPS synthesized?

A
  1. Core is added as monosaccharide to lipid A on cyto side
  2. Flips to peri side
  3. Repeat unit is synthesized on cyto side, added to bactoprenol and flips
  4. Finished LPS translocates to OM by bridging proteins
29
Q

What is mycolic acid used for?

A

Waxy protective coating

30
Q

What is function of arabinogalactan and arabinomannan

A

Anchors waxy part of wall to to PG

Activates HIV-1 expression

31
Q

What is the purpose of the capsule or glycocalyx?

A

Adhesions to surface
Anti-phagocytic
Immune mimic

32
Q

What are pili and fimbriae

A

Short hollow cylinders of pilin and fimbrin

33
Q

What are functions of pili and fimbriae?

A

Hold cells together
Attach cells to surface
Antigenic (cells can vary this to evade hosts)
Motility (twitching)

34
Q

What are flagella composed of?

A

Flagellin

35
Q

How does a flagella move?

A

Protons move through Mot A/B which causes a repulsion

36
Q

What are the three stages of germination?

A

I-activation. Permeabilizes coat
II-initiation-binding of germinant releases autolysin and DPA is released
III-outgrowth-until first division of new cell

37
Q

CCW rotation of flagella causes what?

A

Swimming

38
Q

CW rotation of flagella causes what?

A

Cell tumbles randomly

39
Q

What is S-layer?

A

A layer that surrounds some cells
Acts as a sieve
Might have anti-complement properties

40
Q

When do endospores form?

A

Only under starvation conditions

This triggers membrane kinases that start a phosphorylation cascade ending with SpooA-P

41
Q

What is a spore?

A

A metabolically inactive bacteria with a double membrane around its genetic material

42
Q

What event reactivates a spore?

A

Germination

43
Q

What can trigger germination of a spore?

A

Binding of nutrients

44
Q

What is the difference in peptidoglycan residues between GramNeg and Pos?

A 
Neg = DAP at #3
Pos = Lysine at #3
45
Q

What are all capsules?

A

Polysaccharides except for B. anthracis

Micro (13 decks)

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