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POD > Micro > Flashcards

Micro Flashcards

1
Q

What are the human to human routes of transmission?

A

Respiratory
Fecal-oral
Venereal

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2
Q

What are the human to vertebrate routes of transmission?

A

Vector (biting arthropod)
Vertebrate reservoir
Vector-vertebrate reservoir

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3
Q

What are the benefits of the normal flora?

A

Vitamin K
Occupy niche
Bacteriocidins
Stimulate immune

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4
Q

What tissues are sterile?

A

Blood
Alveoli
Muscle

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5
Q

What are sources of compromise that lead to an opportunistic infection?

A 
Age
Cancer
Nutritional status
Inherited immune deficiencies
HIV
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6
Q

What are Koch’s postulates?

A 
Bacterium in all people who have disease
Isolate
Inoculate susceptible human
Reproduce disease
Reisolate and match
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7
Q

What are the limitations to Koch’s postulates?

A 
Human susceptibility may be inherited
Slow viruses
Hard to culture
Virulence can vary
Ethics
Diseases caused by multiple pathogens
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8
Q

What are two kinds of fungi and how do they differ?

A

Yeasts are unicellular

Molds are multicellular

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9
Q

What is the difference between lytic cycle and a latent infection?

A

Lytic-replicate and released by lysing cell

Latent-replication of a small number of viruses

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10
Q

What are the characteristics of prokaryotes?

A 
No nuclear membrane
Binary fission
Limited repeat/few introns
70S ribosomes
Translation-fmet
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11
Q

What are the characteristics of eukaryotes?

A 
Membrane bound nucleus
mitotic apparatus
repeated DNA/introns
80S ribosomes
Translation-met
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12
Q

What is the difference between prions and viroids?

A

prions-protein only
-Mad Cow, Scrapie, Creutzfeldt-Jakob disease
viroids-RNA only
-mostly plants

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13
Q

What are virulence factors?

A

components of a bacterial cell or virus that enhances its ability to cause disease

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14
Q

What is a flagella and what is it made from?

A

movement

made from flagellin

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15
Q

What are pili and what is it made from?

A

adherence or conjugation

made from pilins

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16
Q

What is a capsule and what is unique about anthrax capsules?

A

confers resistance to phagocytosis
made of polysaccharide
anthrax-polypeptide

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17
Q

What are cytoplasmic inclusion bodies?

A

sites where nutrient macromolecules are located-energy storage

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18
Q

What are endospores?

A

heat resistant can undergo sporulation during nutrient starvation
wall made of calcium dipicolinate

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19
Q

What happens during a Gram stain?

A

dye with purple
add mordant (Gram’s iodine)
wash with alcohol
counter stain

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20
Q

What is the purpose of the alcohol?

A

dehydrates the peptidoglycan layer-more collapse in Gram positive to trap the stain

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21
Q

What is the structure of peptidoglycan?

A

glycan polymers crosslinked by peptide chains
glycan alternates M-G with beta 1,4 linkages
peptide chains coupled to M
pentapeptide bridges (glycine) only present in gram positives
tetrapeptides covalently linked to glycan backbones (AGLA–>3 to 4)

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22
Q

What is teichoic acid? What is lipoteichoic acid?

A

anchors polysaccharides
polymers of ribitol phosphate or glycerol phosphate covalently linked to peptidoglycan phosphodiester linkages
surface antigens

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23
Q

What is the significance of muramyl dipeptide?

A 
produce of peptidoglycan degradation
adjuvant
mitogen
pyrogen
somnagen
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24
Q

Where is LPS located and what is it?

A 
located in outer membrane of gram negative
covalent links between three sections
-lipid A-endotoxic
-core-polysaccharide with KDO
-O antigen-serotyping
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25
Q

What is the endotoxic portion of LPS and what are the effects?

A 
lipid A-->induces IL1 and TNF
sleep
fever
leukopenia
hypoglycemia
hypotension and shock
coagulation
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26
Q

How can you differentiate between LPS and LTA?

A

LTA causes coagulation but not fever

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27
Q

What are porins?

A

proteins that allow passive diffusion of small (less than 600 MW) charged molecules
only found in outer membrane of G-

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28
Q

What is Braun lipoprotein?

A

anchors outer membrane to peptidoglycan

inner leaflet to outer membrane

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29
Q

What are Omp proteins?

A

stabilize the outer membrane and act as receptors

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30
Q

How does peptidoglycan differ in a gram negative cell?

A

only 1-2 layers
no pentapeptide glycine bridge
crosslinked via covalent bond between terminal D-ala to lysine of another tetrapeptide

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31
Q

What is located in the periplasmic space?

A

hydrolytic enzymes including proteases, lipases, nucleases, and components of sugar transport system

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32
Q

How can bacteria be classified?

A 
structure
biochemical typing
serotyping
phage typing
genotyping
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33
Q

What is the most important method for phylogenetic analysis?

A

16S rRNA how closely related organisms are

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34
Q

How do pili contribute to adherence?

A

binding to receptor-either glycoprotein or glycolipid

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35
Q

How do adhesins contribute to adherence?

A

teichoic acids in gram positive

f protein binding to fibronectin

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36
Q

What are biofilms?

A

dense, multiorganism layers on surface

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37
Q

How can bacteria invade?

A

invasins-rearrange actin cytoskeleton

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38
Q

What are siderophores?

A

chelate iron effectively
receptors for transferrin
cytotoxins-damage/kill host cells

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39
Q

How can bacteria evade the immune system?

A

capsules
complement
antigenic switching-H1/H2

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40
Q

What are exotoxins?

A

secreted, located in periplasm of gram negative

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41
Q

How does the diptheria toxin work?

A

ADP-ribosylates host EF-2 protein and shuts down protein synthesis

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42
Q

What are cytolysins?

A

allow water to enter and lyse cell

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43
Q

What are phospholipases?

A

destabilize by cleaving charged heads

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44
Q

What are the components of the cell envelope?

A

plasma membrane+cell wall+intervening material

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45
Q

Where is the tetrapeptide linked?

A

carboxyl group of M of glycan

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46
Q

What is the sacculus?

A

covalent linkage between tetrapeptides allows glycan backbones to be linked together

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47
Q

What does lysozyme cleave?

A

Beta 1,4 linkages

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48
Q

How do bacteria replicate?

A

binary fission

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49
Q

What are the basic nutrient requirements?

A 
glucose
NH4
Mg
Mn
SO4
PO4
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50
Q

What are chemoorganotrophs?

A

all human pathogens are chemoorganotrophs

use glucose, other sugars, aromatics, and organic polymers for carbon and energy

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51
Q

What is fermentation?

A

glycolytic pathway and NAD regeneration (through either lactate or ethanol)
substrate level phosphorylation occurs here
provides intermediates for amino acid, nucleotide

52
Q

Why is the TCA important?

A

generates 4 and 5 carbon intermediates for biosynthetic reactions and reduced NAD/FAD
provides intermediates for amino acid, nucleotide

53
Q

What is important about the electron transport chain?

A

more efficient ATP generation

54
Q

What are prototrophs?

A

no requirements beyond simple carbon, nitrogen and sulfure

55
Q

What are auxotrophs?

A

organisms that require molecules to be added for growth

56
Q

How can oxygen be toxic?

A

final acceptor of electrons in oxidative phosphorylation
can produce superoxide, hydroxyl radical, hydrogen peroxide, hydroxide ion
byproducts can kill cells

57
Q

How can cells remove toxic oxygen?

A

catalase (H2O2–>H2O+O2)
superoxide dismutase (forms H2O2)
peroxidase requires organic electron receptor

58
Q

What are strict aerobes?

A

require oxygen

have SOD and catalase

59
Q

What are strict anaerobes?

A

fermentative

lack SOD and catalase

60
Q

What are aerotolerant anaerobes?

A

fermentative

can scavenge radicals with Mn

61
Q

What are facultative anaerobes?

A

can produce ATP via oxidative phosphorylation or fermentation
can induce SOD and catalase

62
Q

What are mcroaerophilic organisms?

A

require low O2 and generate via oxidative phosphorylation but lack catalase

63
Q

What is the general secretory system?

A

transports proteins to gram positive extracellular or periplasm of gram negative

64
Q

What are sec independent pathways?

A

multiprotein complexes that span the inner and outer membrane (type III acts like a syringe)

65
Q

What are exozymes?

A

virulence factors that help an organism invade, colonize, multiply, or cause disease

66
Q

What is facilitated diffusion and what is an example?

A

mediated by protein, energy independent

glycerol-ATP phosphorylates to help efficiently trap it in the cell

67
Q

What is proton gradient active transport?

A

energy from pumping of protons

uses more energy than group translocation

68
Q

What is ATP dependent active transport?

A

galactose-shock sensitive because protein is in periplasm

more energy than group translocation

69
Q

What is group translocation?

A

complex of phosphotransferase proteins that transfer phosphate group from PEP to sugar
functions as regulator of glucose effect

70
Q

What are examples of siderophores?

A

enterobactin and hydroxamate-bind iron and transport into cell
serve as a virulence factor

71
Q

How doe supercoiling impact replication?

A

negative superhelicity means bacteria DNA can convert to a molecule with unwound helical regions

72
Q

How are replication and cell division coordinated?

A

initiation of chromosome replication coincides with septum formation

73
Q

What are the sigma factor and rho proteins?

A

sigma-initiation site specificity (-10 and -35)

rho-termination

74
Q

What is the consensus sequence?

A

sequence found most frequently

weak promoters may require activator proteins

75
Q

How does Rifampin work?

A

binds to RNAP and inhibits the formation of the first phosphodiester bond-treat mycobacteria and gram positive

76
Q

How does Streptolydigin work?

A

blocks elongation

77
Q

How does Actinomycin D work?

A

blocks movement of RNAP, used in cancer therapy

78
Q

What is the function of the 50S subunit?

A

peptide bond formation

79
Q

What does 23S do?

A

ribozyme-peptidyltransferase

responsible for transpeptidation

80
Q

What does 30S do?

A

initiation and site for tRNA binding

81
Q

What do all proteins start with?

A

f-met

82
Q

What are the stop codons?

A

UAG, UAA, UGA

83
Q

What controls the rate of translation initiation?

A

sequence in 5’ UTR called the Shine-Dalgarno sequence

complementary between 16S rRNA sequence

84
Q

How does streptomycin work?

A

block assembly of 70S initiation complex and cause misreading

85
Q

How does tetracycline work?

A

blocks binding of charged tRNAs to acceptor site

86
Q

How does chloramphenicol work?

A

binds peptidyltransferase and blocks reaction

87
Q

How does erythromycin work?

A

blocks translocation step

88
Q

How can gene expression be controlled?

A 
gene copy number
transcription initiation
mRNA stability
translation initiation
protein stability
89
Q

What is an operator?

A

location where regulatory proteins like repressors bind

90
Q

What is diauxic growth?

A

sequential growth

bacteria preferentially use glucose and then will adjust to lactose when glucose has been depleted

91
Q

What is negative inducible control?

A

inactivation of repressor

92
Q

What is negative repressible control?

A

activates repressor

93
Q

What is positive inducible control?

A

activates activator

94
Q

What is positive repressible control?

A

inactivates activator

95
Q

What happens to the lac operon in the presence of glucose?

A

no transcription
repressor bound
low cAMP
IIIGlc stops transport of sugars

96
Q

What happens to the lac operon in the presence of lactose?

A

allolactose changes repressor (unbound)
high PIIIGlc leads to high cAMP (transport of sugars not inhibited)
cAMP activates the activator (CAP)

97
Q

What happens to the lac operon in the presence of lactose and glucose?

A

allolactose changes repressor so it is unbound

IIIGlc stops transport of sugar (activator is not activated-low cAMP)

98
Q

How do two component regulators work?

A

first component senses environment-can be a protein kinase

second component-transcriptional activator

99
Q

What is quorum sensing?

A

genes activated when concentration of bacteria reaches a threshold

100
Q

What is global regulation?

A

regulation of multiple metabolic pathways by single regulator

101
Q

What is a bacteriophage? What are the components?

A

virus that infects bacteria
nucleic acid-ss or ds, RNA or DNA
capsid of proteins

102
Q

What does phage lambda infect?

A

E. coli

103
Q

What does P22 infect?

A

Salmonella

104
Q

How does T1 infect?

A

tonB receptor (enterochelin receptor)

105
Q

How does lambda infect?

A

maltose binding protein

106
Q

How does MS2 infect?

A

sides of flagella

107
Q

How does F1 infect?

A

tip of the flagella

108
Q

How does the chromosome circularize?

A

binding at the cohesive ends (cos sites)

109
Q

How does a lytic virus replicate? What is formed?

A

rolling circle mechanism

forms concatamers

110
Q

How does a lysogenic virus integrate?

A

reciprocal recombination at attachment sites (att)

111
Q

How can a lysogenic virus switch to lytic?

A

mutation leads to activation of recA to cleave the repressor

112
Q

How does cholera become virulent?

A

presence of CTX phage

113
Q

How does diptheria become virulent?

A

prophage B toxin

114
Q

What is a meroploid?

A

partially diploid organism

115
Q

What is complementation analysis?

A

mutation in two genes
if mutation phenotype persists-same gene
if normal phenotype-different genes (intergenic complementation occurred)

116
Q

What is transformation?

A

uptake of naked DNA into a cell followed by recombination or replication

117
Q

What determines whether the DNA will recombine or replicate?

A

homology to genome

118
Q

What is transduction?

A

transferring of host DNA to recipient by bacteriophage

119
Q

What is generalized transduction?

A

mistakenly packages host DNA

120
Q

What is specialized transduction?

A

leaves some of its DNA and takes some host DNA because adjacent region was excised imprecisely

121
Q

What is conjugation?

A

transfer of DNA from one bacterial cell of one mating type to another

122
Q

What is the F+ plasmid?

A

self replicating plasmid

123
Q

What is the Hfr chromosome?

A

integrate, mediated by IS regions (homology)

genes near integration are transferred at a high frequency

124
Q

What is a F’ plasmid?

A

excise imprecisely from Hfr chromosome and take bacteria with it

125
Q

What is type I excision?

A

portion of F left behind and portion of bacteria taken instead

126
Q

What is type II excision?

A

portion of bacteria taken in addition to the full F plasmid

127
Q

What is the R plasmid? What is an example of acquiring antibiotic resistance?

A

R plasmid confers resistance to antibiotics

MRSA gaining vancomycin resistance associated with enterococcus faecalis

POD (4 decks)

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