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Micro Exam #2 > Morphology and Ultrastructure > Flashcards

Flashcards in Morphology and Ultrastructure Deck (85)
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1

Average size of a bacterium?

1 uM

2

List a few unique cellular features of Bacteria?

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

3

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

Purple = Positive
Red = Negative

4

What two criteria are primarily used for classification?

Size/shape
Gram +/-

5

What do you do in a gram stain?

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

6

What makes a gram + purple?

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

7

What stain you yo use for mycobacterium?

Acid-Fast Staining

8

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

PCR
Esp. Important for slow growing strands

9

The lack of a bacterial nuclear membrane allows for...

Coupled Transcription and Translation

10

Location of DNA in the bacterial cell?

the nucleoid and plasmids

11

Size of two subunits and full ribosome complex?

30S + 50S = 70S

12

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

Steroids

13

Three important roles of the bacterial lipid bilayer?

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

14

Describe a G+ cell wall

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

15

What does lysozyme do to fight bacteria?

Cleaves glycan backbone of peptidoglycan
Death by loss of osmotic control

16

Are peptidoglycan and techoic acid still present in gram negs?

A little PG
No TA

17

What parts of PG binds to provide crosslinkage?

D-Ala to Lys

18

Two repeating subunits in PG?

NAG and N-Acetylmuranic Acid

19

Importance of the periplasmic space in gram negatives?

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

20

Type ___ virulence factors are a major virulence factor

III

21

Describe the outer membrane of a gram negative.

Inside normal, outside LPS

22

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

Endotoxin
Schwartzman Rxn

23

What is LPS without its O antigen?

LOS (lipooligosaccharide)

24

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

Porins.
Materials under 700 Da

25

Role of lipoproteins in G- bacteria?

Hold outer membrane onto the bacteria

26

How is LPS crosslinked?

Mg and Ca linkages between phosphates

27

What is a bacterial capsule?

A loos polysaccharide or protein layer
"Glycocalyx"

28

Why do we can about bacterial capsules?

Poorly Antigenic
Anti-phagocytotic
Increase Adherance -- Biofilms in quorum

29

What are flagella?

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

30

What are fimbriae?

Hair-like projections outside the cell made of Pilin.

31

Why do we care about fimbriae?

They increase adherance, and may have specific binding
Also, encompass the F pili

32

How is mycoplasma an exception to the rule?

Steals host steroids

33

Role of bactoprenol?

Conveyor belt for precursors to the cell surface
There they can be activated with high energy bonds

34

Describe the process of peptidoglycan synthesis.

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

35

What antibiotic works by blocking bactoprenol recycling?

Bacitracin

36

What reaction frovides peptide cross-linkage for developing LPS?

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

37

Other name for transpeptidases invovled in LPS formation?

Penicillin-binding proteins
(Because targeted by penicillin and other beta lactams)

38

How does vancomycin work?

Blocks D-Ala D-Ala site

39

Three primary components of LPS?

Lipid A
Core Polysacharide
O Antigen

40

What is Lipid A? What does it do?

Glucosamine Disacharide Backbone

Endotoxin Activity, FA Anchor in Outer Mem

41

What is Core polysaccharide?

Branched, 9-12 sugars
2-keto-3-deoxy-octenoate (KDO)

42

What is an O Antigen?

50-100 sach. units

43

What is a septum?

A bacterial cross wall generated in the process of cell division

44

Difference between streptococci and staphylococci cell division?

Strep divid at 180 degrees -- Make chains
Staph divide at 90 degrees -- form bundles

45

How are chains/cluters of bacteria formed?

Incomplete clevage.

46

Spores are ______ gram negative.

NEVER

47

Describe the protein coat of a spore.

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

48

What is required for a spore to germinate?

H2O and Trigger Nutrients

49

How do bacteria transfer genes between them?

F Pilus

50

Shape of vibrio?

Comma

51

Shape of spirochete?

Spring

52

Shape of Spirillum?

Lazy S

53

Shape of Coccus?

Round

54

How might relatedness of two bacterial strands be assessed?

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

55

How are DNA optical maps made?

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

56

Difference between USA 300 and USA800

300 -- community acquired, commonly abx resistant with toxin
800 -- Hospital resistant, less significant

57

What does an H antigen correspond with?

Flagellar Antigens

58

What does an O antigen correspond with?

Outer Membrane

59

What does a K antigen correspond with?

Capsule

60

Cell shape of mycoplasma?

Highly pleomorphic

61

Why are mycoplasma obligate parasites?

They require cholesterol from eukaryotic cell hosts

62

What shape do fusiform bacteria maintain?

Spindle

63

Why do archaea tend to be ignored in medical microbiology?

No known diseases assiciated

64

How do archaea maintain stability in high temperatures?

Monolayer of lipids instead of a bilayer

65

How do bacteria usually divide?

Binary fission

66

Three examples of membrane invaginations?

Mesosomes
Phycobilisomes
Chromatophores

67

What are cytoplasmic somal bodies?

Storage Organelles

68

What are inclusion bodies?

Insoluble polymers

69

What are three types of inclusion bodies?

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

70

What are enzymatic reaction centers?

Locations of DNA, RNA, and Protein localization

71

What are plectonemes?

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

72

How do materials get through the bacterial plasma membrane?

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

73

How do bacteria perform endocytosis.

They don't.

74

Secretory systems that have a needle complex?

3, 4, 6

75

How are GlcNAc and MurNAc linked?

beta 1-4 glycocidic bond

76

As PG breaks down, what activated the immune response?

GlcNAc-MurNAc disaccharide

77

What is a limit of bacitracin activity?

It will only kill growing cells

78

How is the LPS core generated?

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

Significance to sialic acid in immune response?

Causes the capsule to mimic self-antigen

80

Significance of pilin in immune response?

Bacteria can switch pilin when detected by the immune system

81

Difference between flagella and eukaryotes and prokaryotes?

Euk -- Back and Forth
Pro -- Propeller

82

What causes the flagella to spin?

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

83

What is the C ring?

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

84

How does chemotaxis work?

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

Significance of S-layers?

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