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Micro Exam #2 > Morphology and Ultrastructure > Flashcards

Morphology and Ultrastructure Flashcards

1
Q

Average size of a bacterium?

A

1 uM

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2
Q

List a few unique cellular features of Bacteria?

A

Lack of nucleus and other membranes organelles
DS circular DNA
Smaller Ribosomes (70S)
Plasmids

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3
Q

In gram staining, what colors do positive and negative turn?

A 
Purple = Positive
Red = Negative
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4
Q

What two criteria are primarily used for classification?

A

Size/shape

Gram +/-

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5
Q

What do you do in a gram stain?

A

Smear, Heat fixation, crystal violet + iodine, wash, safranin

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6
Q

What makes a gram + purple?

A

Stain gets trapped in the thick, cross-linked peptidoglycan layer.

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7
Q

What stain you yo use for mycobacterium?

A

Acid-Fast Staining

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8
Q

How (what lab technique) would you use to assess bacterial genetics? When would this be important?

A

PCR

Esp. Important for slow growing strands

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9
Q

The lack of a bacterial nuclear membrane allows for…

A

Coupled Transcription and Translation

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10
Q

Location of DNA in the bacterial cell?

A

the nucleoid and plasmids

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11
Q

Size of two subunits and full ribosome complex?

A

30S + 50S = 70S

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12
Q

With the exception of myco, what do bacterial cell membranes lack?

A

Steroids

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13
Q

Three important roles of the bacterial lipid bilayer?

A

Electron Transport/Energy Production
Pumps present to maintain internal environment
Lined internall with actins that determine shape/division

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14
Q

Describe a G+ cell wall

A

Thick, multilayered
Mostly Peptidoglycan
Teichoic Acids Make covalent linkages and anchor to membrane

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15
Q

What does lysozyme do to fight bacteria?

A

Cleaves glycan backbone of peptidoglycan

Death by loss of osmotic control

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16
Q

Are peptidoglycan and techoic acid still present in gram negs?

A

A little PG

No TA

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17
Q

What parts of PG binds to provide crosslinkage?

A

D-Ala to Lys

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18
Q

Two repeating subunits in PG?

A

NAG and N-Acetylmuranic Acid

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19
Q

Importance of the periplasmic space in gram negatives?

A 
Breakdown molecules (proteases, phosphotases, lipases)
Many lytic virulence factors
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20
Q

Type ___ virulence factors are a major virulence factor

A

III

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21
Q

Describe the outer membrane of a gram negative.

A

Inside normal, outside LPS

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22
Q

LPS is also known as ______. When released it triggers a _______.

A

Endotoxin

Schwartzman Rxn

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23
Q

What is LPS without its O antigen?

A

LOS (lipooligosaccharide)

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24
Q

What are the transmembrane proteins called? What gets through them?

A

Porins.

Materials under 700 Da

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25
Q

Role of lipoproteins in G- bacteria?

A

Hold outer membrane onto the bacteria

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26
Q

How is LPS crosslinked?

A

Mg and Ca linkages between phosphates

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27
Q

What is a bacterial capsule?

A

A loos polysaccharide or protein layer

“Glycocalyx”

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28
Q

Why do we can about bacterial capsules?

A

Poorly Antigenic
Anti-phagocytotic
Increase Adherance – Biofilms in quorum

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29
Q

What are flagella?

A

Ropelike cellular propellers made of heavily coiled flagellin.
Driven by ATP motor and chemotactic signals

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30
Q

What are fimbriae?

A

Hair-like projections outside the cell made of Pilin.

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31
Q

Why do we care about fimbriae?

A

They increase adherance, and may have specific binding

Also, encompass the F pili

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32
Q

How is mycoplasma an exception to the rule?

A

Steals host steroids

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33
Q

Role of bactoprenol?

A

Conveyor belt for precursors to the cell surface

There they can be activated with high energy bonds

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34
Q

Describe the process of peptidoglycan synthesis.

A

Precursors made in cell
UDP-MurNAC attached to Bactroprenol via UMP release
GlcNAC is added
Translocation to the outside of the cell
Transglycosylases use the pyrophosphate to attach the GlcNAC-MurNAC to the peptidoglycan chain
Bactoprenol is recycled

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35
Q

What antibiotic works by blocking bactoprenol recycling?

A

Bacitracin

36
Q

What reaction frovides peptide cross-linkage for developing LPS?

A

Transpeptidation from 3rd free amino and D alanine in the 4th position of the other peptide

37
Q

Other name for transpeptidases invovled in LPS formation?

A

Penicillin-binding proteins

Because targeted by penicillin and other beta lactams

38
Q

How does vancomycin work?

A

Blocks D-Ala D-Ala site

39
Q

Three primary components of LPS?

A

Lipid A
Core Polysacharide
O Antigen

40
Q

What is Lipid A? What does it do?

A

Glucosamine Disacharide Backbone

Endotoxin Activity, FA Anchor in Outer Mem

41
Q

What is Core polysaccharide?

A

Branched, 9-12 sugars

2-keto-3-deoxy-octenoate (KDO)

42
Q

What is an O Antigen?

A

50-100 sach. units

43
Q

What is a septum?

A

A bacterial cross wall generated in the process of cell division

44
Q

Difference between streptococci and staphylococci cell division?

A

Strep divid at 180 degrees – Make chains

Staph divide at 90 degrees – form bundles

45
Q

How are chains/cluters of bacteria formed?

A

Incomplete clevage.

46
Q

Spores are ______ gram negative.

A

NEVER

47
Q

Describe the protein coat of a spore.

A

Inner Mem + 2x Peptidoglycan + outer kertain-like protein coat

48
Q

What is required for a spore to germinate?

A

H2O and Trigger Nutrients

49
Q

How do bacteria transfer genes between them?

A

F Pilus

50
Q

Shape of vibrio?

A

Comma

51
Q

Shape of spirochete?

A

Spring

52
Q

Shape of Spirillum?

A

Lazy S

53
Q

Shape of Coccus?

A

Round

54
Q

How might relatedness of two bacterial strands be assessed?

A

Biochemical tests of metabolically active
DNA optical mapping
Serotyping
Direct Gene Comparisons (Virochip)

55
Q

How are DNA optical maps made?

A

Restriction endonucleases cut DNA at different sequences then maps are made that show the points they come back together

56
Q

Difference between USA 300 and USA800

A

300 – community acquired, commonly abx resistant with toxin

800 – Hospital resistant, less significant

57
Q

What does an H antigen correspond with?

A

Flagellar Antigens

58
Q

What does an O antigen correspond with?

A

Outer Membrane

59
Q

What does a K antigen correspond with?

A

Capsule

60
Q

Cell shape of mycoplasma?

A

Highly pleomorphic

61
Q

Why are mycoplasma obligate parasites?

A

They require cholesterol from eukaryotic cell hosts

62
Q

What shape do fusiform bacteria maintain?

A

Spindle

63
Q

Why do archaea tend to be ignored in medical microbiology?

A

No known diseases assiciated

64
Q

How do archaea maintain stability in high temperatures?

A

Monolayer of lipids instead of a bilayer

65
Q

How do bacteria usually divide?

A

Binary fission

66
Q

Three examples of membrane invaginations?

A

Mesosomes
Phycobilisomes
Chromatophores

67
Q

What are cytoplasmic somal bodies?

A

Storage Organelles

68
Q

What are inclusion bodies?

A

Insoluble polymers

69
Q

What are three types of inclusion bodies?

A

poly-beta-OH butyrate, starch, glycogen (Carbon)
Sulfur (sink for sulfur oxidizers)
Polyphosphate granules

70
Q

What are enzymatic reaction centers?

A

Locations of DNA, RNA, and Protein localization

71
Q

What are plectonemes?

A

DNA supercoils that are a part of colocating genes and proteins that work together

72
Q

How do materials get through the bacterial plasma membrane?

A

Rocker-Switch Mechanism – External and internal binding sites, bottleneck that is sometimes a selectivity filter

73
Q

How do bacteria perform endocytosis.

A

They don’t.

74
Q

Secretory systems that have a needle complex?

A

3, 4, 6

75
Q

How are GlcNAc and MurNAc linked?

A

beta 1-4 glycocidic bond

76
Q

As PG breaks down, what activated the immune response?

A

GlcNAc-MurNAc disaccharide

77
Q

What is a limit of bacitracin activity?

A

It will only kill growing cells

78
Q

How is the LPS core generated?

A

Added as monosaccharide units to Lipid A on the cytosolic side, then flipped to the outside

Repeat unit is synthesized by cytoplasm, carried to peri by bactoprenol, added to core

transfer to OM by periplasm-bridging proteins

79
Q

Significance to sialic acid in immune response?

A

Causes the capsule to mimic self-antigen

80
Q

Significance of pilin in immune response?

A

Bacteria can switch pilin when detected by the immune system

81
Q

Difference between flagella and eukaryotes and prokaryotes?

A

Euk – Back and Forth

Pro – Propeller

82
Q

What causes the flagella to spin?

A

Proton gradient moving through the rotor (Mot A/B proteins)

83
Q

What is the C ring?

A

A switch that allows rotation to change direction
CCW – Swim
CW – Tumble

84
Q

How does chemotaxis work?

A

Attractant binds to MCP which blocks CHEA activity
CHE A can no longer trigger CHE Y
CHE Y can’t cause tumble
Keep swimming to attractant
Methylation of alpha helix in MCP undoes attractant activity

85
Q

Significance of S-layers?

A

Single crystalline protein that surrounds some cells
Molecular Sieve
Protects from complement

Micro Exam #2 (15 decks)

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