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
