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Microbio > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q
  • regulates the expression of a structural gene
  • does not encode RNA or protein
  • includes promoters and binding sites for regulatory proteins
A

DNA control sequence

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2
Q
  • all the genetic information that defines an organism
  • consists of one (usually) or more DNA chromosomes
A

genome

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3
Q

made up of contiguous packets of information called genes

A

chromosomes

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4
Q

produces a functional RNA, which usually encodes a protein

A

structural gene

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5
Q
  • identifies conserved sequences
  • the consensus sequence for sigma-70 promoters is called
A

the -10/-35 box

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6
Q
  • subunit that directs RNA pol to different genes as needed to initiate transcription
  • dissociates
A

sigma factors

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7
Q

always transcribing (s70 in E. coli)

A

housekeeping sigmas

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8
Q

recognize different promoters

A

specialized sigma factors

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9
Q

recognize promoters for genes that encode nitrogen metabolism and other functions

A

sigma 54

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10
Q

recognize promoters for genes that are heat shock-induced

A

sigma 32

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11
Q

recognize promoters for genes that encode motility and chemotaxis

A

sigma 28

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12
Q

recognize promoters for genes that encode stationary-phase and stress responses

A

sigma 38

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13
Q

what is the function of the omega subunit of the RNA polymerase holoenzyme

A

helps to protect the integriity of the complex in stressful situations

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14
Q

act as scaffolding proteins in the RNA polymerase holoenzyme

A

alpha 1 and alpha 2

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15
Q

what is the function of the Beta (and Beta prime) subunits of the RNA polymerase holoenzyme

A

catalyzes the synthesis of RNA

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16
Q

when the sigma factor is bound to the core enzyme, the six-subunit complex is termed

A

the RNA polymerase holoenzyme

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17
Q

RNA polymerase DNA and lays down a complementary and antiparallel strand of RNA

A

transcription

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18
Q

stages of transcription

A
  • initiation
  • elongation
  • termination
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19
Q

RNA transciption begins at which nucleotide

A

+1

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20
Q

in bacteria, a gene can operate independently or in tandem with other genes in

A

an operon

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21
Q

1 gene under control of a single promoter

A

monocistronic RNA

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22
Q

more than one gene under control of a single promoter

A

polycistronic RNA

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23
Q

occurs when a bacteriophage accidentally packages a fragment of host cell DNA

A

transduction

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24
Q

steps to transduction

A
  1. P22 phage DNA infects a host cell and makes subunit components for more phage
  2. DNA is packaged into capsid heads, some capsids package host DNA
  3. new phage assembly is completed
  4. cell lyses; phage is released
  5. transducing phage particle injects host DNA into new cell, where it may recombine into the chromosome; recombination crossover events exchange host DNA for donor DNA
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25
Q

what genome characteristics would be useful for computationally identifying genes acquired by HGT

A
  • guanine-cytosine content
  • codon usage
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26
Q

benefits of fast replication of bacteria

A
  • competitive advantage
  • rapid evolution
  • rapid colonization
  • biofilm formation
  • survival under stress and changing conditions
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27
Q

what features enable prokaryotes to replicate rather quickly

A
  • small genomes that contain only essential genes
  • genes lack introns
  • only short control sequences between genes (high gene density)
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28
Q
  • form when an integrated F plasmid is inaccurately excised from the genome
  • some host cell DNA is excised and ends up on the plasmid
A

F’ plasmid

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29
Q

what happens when the F’ plasmid conjugates

A

sends host cell DNA to recipient

  1. the F factor loops out of the chromosome with thr and leu genes in the loop
  2. a crossover excises the F factor carrying the thr and leu genes, producing an F’ thr leu
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30
Q

can transfer chromosomal genes between cells

A

integration of the F- plasmid

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31
Q

which type of genome has a lot less non-coding DNA

A

bacterial genomes

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32
Q

methods of gene transfer

A
  • vertical gene transfer
  • horizontal gene transfer
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33
Q
  • allows the introduction of new genes into an organism that may be of selective advantage
  • segments of DNA can move between bacteria
A

horizontal gene transfer

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34
Q

the introduction of extracellular DNA directly into an organism

A

transformation

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35
Q

cells express machinery for DNA uptake (proteins are encoded in the genome)

A

natural competence

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36
Q

researchers make cells competent through electrical or chemical manipulation

A

induced/artifical competence

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37
Q

the transfer of DNA from cell to cell via direct contact/sex pilus formation

A

conjugation

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38
Q

steps to conjugation

A
  1. the F+ plasmid donor extends the sex pilus component of its T4SS, making contact with the F- recipient cell
  2. contraction of the pilus draws the two cells together. Relaxase unwinds the DNA at oriT; a second relaxase is recruited to this bubble
  3. one strand of the F factor is nicked at the nic site in oriT. one relaxase attaches to the 5’ end of the nicked strand and trasnfers it through teh T4SSS. the other relaxase remains in the donor and unwinds the DNA
  4. the strand remaining in the donor replicates by DNA pol III
  5. once in the recipient, the transferred strand circularizes and replicates by DNA pol III
  6. the recipient has been converted to a donor
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39
Q

the sequential addition of ribonucleotides

A

elongation

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40
Q

relies on a protein called rho and a strong pause site at the 3’ end of the gene

A

Rho-dependent transcription termination

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41
Q
A
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42
Q

requires a GC-rich region of RNA, as well as 4-8 consecutive U residues (terminator haripin loop and RNA being built)

A

Rho-independent transcription termination

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43
Q

functions as ATPase and RNA-DNA helicase activity

A

Rho

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44
Q

steps to rho-dependent termination

A
  1. Rho binds to C-rich regions
  2. Rho is threaded through Rho hexamer, pulling Rho toward RNA polymerase
  3. contact between Rho and RNA polymerase causes termination
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45
Q

contact between hairpin, NusA protein, and RNA polymerase cause termination

A

Rho-independent termination

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46
Q

70S

A

prokaryotic ribosome

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47
Q

80S

A

eukaryotic ribosome

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48
Q

happens at ribosomes

A

translation

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49
Q
A
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49
Q

match amino acids to mRNA

A

tRNAs

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50
Q

amino acids are linked to this region of tRNA through charging

A

acceptor end

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51
Q

when is translation initiated in bacteria

A

when the 16S rRNA recognizes the Shine-Dalgarno sequence

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52
Q

AGGAGG at the 5’ end of bacterial mRNA; positions the start codoon into catalytic site for translation

A

Shine-Dalgarno sequence

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53
Q

how do eukaryotes initiate translation

A

through recognition of the 5’ cap and start codon

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54
Q

what happens in eukaryotes vs prokaryotes if there is a start codon mutation

A
  • eukaryotes: keeps scanning
  • prokaryotes: ribosome gets stuck and translation does not begin
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55
Q

after inititation, the ribosome moves along the RNA until

A

it reaches a stop codon

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56
Q

what prevents the degradation of mRNA in prokaryotes

A

coupling of transcription and translation

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57
Q

have multiple Shine-Dalgarno sequences

A

polycistronic mRNAs

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58
Q

accepts the incoming aminoacyl-tRNA

A

A site of ribosome

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59
Q

holds the tRNA with the peptide attached, which is to be transferred to the new amino acid residue in the course of the peptidyltransferase reaction

A

P site of ribosome

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60
Q

which type of control system is most efficient in resource usse

A

transcriptional control

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61
Q

which type of genomic control is fastest

A

post-translational

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62
Q

bind DNA near the promoter, affects transcription

A

regulatory proteins

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63
Q

DNA sequences recognized by regulatory proteins

A

sequence motifs

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64
Q

what is the effect of an activator on transcription

A

increases transcription (positive regulation)

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65
Q

what is the effect of a repressor on transcription

A

decreases transcription (negative regulation)

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66
Q

protein binds to DNA, assisting binding of RNAP

A

activator

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67
Q

protein binds to DNA, blocking RNAP

A

repressor

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68
Q

effects on transcription when the activator binding site is occupied

A

increases transcription

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69
Q

effects on transcription when the operator is occupied

A

decreases transcription

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70
Q

DNA sequence bound by activator

A

activator binding site

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71
Q

DNA sequence bound by repressor

A

operator

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72
Q

small molecules that bind to regulator proteins to modify their activity; help regulatory proteins to modify their activity

A

effectors

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73
Q

enable activators or disable repressors

A

inducers/coactivators

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74
Q

enable repressors or disable activators

A

corepressors

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75
Q

what type of operon utilzes corepressors

A

repressible operons

decreases transcription when present

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76
Q

what type of operon utilizes inducers/coactivators

A

inducible operons

increase transcription when present

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77
Q

true or false:

gene transcription is all or nothing: off is zero

A

false

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78
Q

located in E. coli genome, encodes the proteins needed to catabolize lactose

A

Lac operon

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79
Q
  • plays as an inducer
  • breaks lactose into monosaccharides
  • encoded by LacZ
A

B-Galactosidase

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80
Q
  • brings lactose into cell, transport protein
  • encoded by LacY
A

lactose permease

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81
Q
  • moves acetyl group
  • not really understood
  • encoded by LacA
A

thiogalactoside transacetylase

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82
Q

encodes Lac repressor

A

LacI

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83
Q

compared to the eukaryal genome, the bacterial genome

A

contains a larger percent of DNA that encodes for functional proteins

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84
Q

characteristics of HGT

A
  • transduction, conjugation, transformation
  • genes from one independent mature organsim transferred to another mature organism
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85
Q

Suppose a microbe has died and lysed, exposing its DNA to the environment. Some of this DNA was taken up by another unrelated microbe and incorporated into its genome. This is an example of which process(es)?

A

transformation (HGT)

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86
Q

carries genes responsible for formation of sex pili, has several insertion elements to assist plasmid integration into host cell’s chromosome

A

F plasmid

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87
Q

following an F+ x F- mating, the donor is … and the recipient is …

A

F+, F+

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88
Q

the order of gene transfer in a completed Hfr x F- mating is best represented by

A

part of the plasmid followed by the chromosome followed by the rest of the plasmid

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89
Q

suppose a strain of E. coli is identified as an Hfr strain. In a conjugal experiment between the donor Hfr strain and a recipient E. coli strain that is F-, what would you expect to result

A

the recipient to remain F-

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90
Q

an Hfr cell and an F- cell result from conjugation between a donor cell and a recipient cell. which statements are true regarding this event

A
  • donor could have been Hfr
  • recipient could have been F-
91
Q

if a segment of RNA reads 5’ GCCUUAA 3’, then the corresponding DNA template strand reads

A

5’ TTAAGGC 3’

92
Q

in the language of nucleic acids, sequences that are complementary…

A

have matching nucleotides, A with T or U and G with C

93
Q

when compared to a template strand of DNA, the corresponding RNA strand is

A

complementary

94
Q

the mRNA of bacterial cells is often polycistronic. what does this term mean?

A

it contains the code for multiple peptides

95
Q

which statement best describes the process of prokaryotic transcription initiation

A

sigma factor directs RNA polymerase to the promote by binding the -10 and -35 regions

96
Q

the sigma factor is directly required for

A

transcription initiation

97
Q

in E. coli, why is sigma-70 considered the “housekeeping” sigma factor

A

it keeps essential gnes and pathways operating

98
Q

a Rho-independent terminator

A

is a hairpin loop structure that forms in RNA

99
Q

the termination of transcription can be caused by which of the following

A
  • stem-loop structure and NusA
  • Rho factor
100
Q

what is common to both rho-dependent and rho-independent transcription termination

A

both types of termination occur following a pause by the polymerase

101
Q

the 30S and 50S ribosomal subunits are so designated to indicate

A

their sedimentation rate in a centrifuge

102
Q

three bases on the mRNA that is read by the ribosome in the 5’ to 3’ direction

A

codon

103
Q

a mutation occurs upstream of gene A in the region encoding the ribosome binding site. predict how this mutation will impact the levels of mRNA and protein preduced for gene A

A

mRNA levels will remain constant, proteins will decrease

104
Q

the ability of Vibrio fischeri to produce bioluminescence chemicals only when a certain population density has been reached relies on control of the lux operon, which is regulated by

A

positive control by an activator protein

105
Q

upon reorienting after a tumble, an E. coli cell

A

points in a random direction

106
Q

an E. coli strain is mutated such that it can only rotate its flagellum in the counterclockwise direction. therefore, this strain moves in what manner

A

runs only

107
Q

motile bacteria have been placed in an environment with a gradient of a chemical attractant. which of the following behaviors would you predict

A

the bacteria will both reduce tumbling frequency and increase run duration in the direction of the chemical

108
Q

In E. coli, chemotaxis signaling relies on Che proteins. In response to an attractant, which of the following ultimately results in a run

A

decreased phosphorylation of CheA

109
Q

what is the role of CheR in the E. coli positive chemotaxis pathway

A

adaptation; methylates and desensitizes the chemoreceptor to the attractant

110
Q

what parts of a virus are always found in every virus

A
  • nucleic acid
  • capsid
111
Q
A
112
Q

what is the viral capsid composed of

A

protein

113
Q

how big are most viruses compared to the cells they infect

A

much smaller–between 10-100nm

114
Q

steps to viral replication

A
  1. bind receptor on host cell
  2. viral particle enters host cell
  3. uncoating viral particle to make genetic material accessible
  4. replication of viral genetic material
  5. assembly of mature viral particles
  6. exit out of host cell
115
Q

the range of cell types that can serve as host for viral infection

A

host range

116
Q

a specific animal virus always infects

A

the number of species depends on the virus

117
Q

what determines host range?

A

receptor on cell surface

118
Q

compared with cellular genomes, viral genomes

A

are smaller, with fewer base pairs

119
Q

viral genomes may comprise

A

ds/ssDNA or ds/ssRNA

120
Q

compared with cells that are surrounded by a lipid membrane, viruses

A

may be surrounded by a membrane derived from the host cell

121
Q

a non-enveloped virus will have its attachment proteins present in its

A

capsid

122
Q

how can the seven Baltimore classes of viruses be distinguished from one another

A
  • nucleic acid usage (DNA vs RNA)
  • ss or ds
  • utilization of reverse transcriptase
  • positive or negative sense
123
Q

which viral genome can be immediately translated upon entry into the host cell

A

positive-sense RNA

124
Q

which enzyme is utilized by a human host for genome replication

A

DNA dependent DNA polymerase

125
Q

which enzyme is utilized by a human host for transcription

A

DNA dependent RNA polymerase

126
Q

in which subcellular compartment would you expect to find human polymerases

A

nucleus

127
Q

adenoviruses are a family of Baltimore Group I viruses that cause the common cold in humans. based on this, which description best fits the Adenovirus family

A

double stranded DNA virus using DNA polymerase to replicate

128
Q

what enzyme do “typical” group 1 viruses that enter the host nucleus use to replicate their genome

A

host encoded DNA dependent DNA polymerase

129
Q

members of the poxviridae family are atypical Group I viruses that replicate and transcribe their genome through the use of

A
  • virus encoded DNA-dependent RNA polymerase
  • virus encoded DNA-dependent DNA polymerase
130
Q

reoviruses are a family of Baltimore Group III viruses that cause diarrheal disease in infants. based on this, which description best fits the reovirus family

A

dsRNA viruses using an RNA polymerases to replicate

131
Q

a viral genome contains 5% adenine, 25% thymine, 29% guanine, and 41% cytosine. thus, this virus belongs to Baltimore Group …

A

2

132
Q

when a group IV virus infects a human cell, many copies of its genome are produced and packaged into new virions. what type of molecule is used as a template for the production of many genome copies

A

dsDNA

133
Q

what type of enzyme is carried in the capsid of Group V

A

RNA dependent RNA polymerase

134
Q

HIV uses a viral enzyme called reverse transcriptase to synthesize DNA for integration into the host genome. what is another name for HIV viral reverse transcriptase

A

RNA dependent DNA polymerase

135
Q

which enzyme transcribes the integrated HIV genome to make mRNA

A

host RNA polymerase

136
Q

there are fewer antivirals currently available in most pharmacies than there are antibacterials because

A

selective toxicity is much easier to achieve for bacteria

137
Q

true or false:

unlike bacteria, viruses do not develop resistance to antiviral drugs

A

false

138
Q

the Lac operon is regulated by a negative inducible system that responds to …

A

allolactose

139
Q

the lac operon is regulated by a positive inducible that responds to

A

glucose

140
Q

what is the relationship between cAMP and glucose concentration

A

inversely proportional

less glucose = more cAMP

141
Q

what happens to the phosphotransferase system when glucose is present

A

PTS blocks lactose uptake

inducer exclusion

142
Q

what happens in the PTS in the absence of glucose

A

phosphorylated IIA accumulates and LacY is free to transport lactose

143
Q

what happens in the presence of glucose in the PTS (steps)

A
  • glucose moves from protein IIC to IIB, wich transfers a phosphate from IIA to glucose
  • unphosphorylated IIA(Glc) inhibits lacY

inducer exclusion

144
Q
A
144
Q
A
145
Q

what happens during the first log phase of the dilauxic growth curve

A
  • glucose is utilized – intracellular cAMP low
  • intracellular allolactose low
  • lac repressor bound to operator
146
Q

what happens in the second log phase of the dilauxic growth curve

A
  • lac repressor bound to inducer
  • crp activator bound to coactivator and activator bound to ABS
  • transcription of lac operon occurring at high levels
147
Q

codes for enzymes needed to synthesize tryptophan

A

Trp operon

148
Q

which stem loop terminates transcription

A

3:4

149
Q

transcription is regulated at which levels

A

intitiation (repressor) and elongation (attenuation)

150
Q

steps to what occurs in the trp operon in high tryptophan environments

A
  1. ribosome translates through trp operons and encounters translation stop codon
  2. ribosome stops covering mRNA regions 1 and 2. polymerase continues to transcribe regions 3 and 4. the 3:4 termination loop forms
  3. the 3:4 loop binds RNA polymerase and causes its release before reaching trpE
151
Q

what happens in the trp operon when there are low levels of tryptophan

A
  1. ribosome initiates leader
  2. scarce trp tRNA makes ribosome stall at trp codons. polymerase continues through attenuator
  3. stalled ribosome covers region 1, allowing 2:3 stem loop to form. the less energetically favorable 3:4 transcription terminator loop cannot form
  4. polymerase transcribes trpE
152
Q

coordinates gene expression within a dense population

A

quorum sensing

153
Q

percent of population that needs to have immunity to prevent the spread of disease

A

herd immunity

154
Q

factors that play a role in herd immunity

A
  • how easily the disease is spread
  • population density
  • vaccine efficiency
155
Q
  • provide your body with instructions for making pathogen proteins
  • a vaccine that uses a viral vector to deliver genetic material that can be transcribed by the recipient’s host cells as mRNA coding for a desired protein, or antigen, to elicit an immune response
A

viral vector vaccines

156
Q

a type of vaccine that uses a copy of a molecule called messenger RNA to produce an immune response

A

mRNA vaccines

157
Q

vaccines derived from one or more components, such as capsid subunit proteins produced by engineered industrial bacteria

A

subunit vaccines

ex: HPV, Shingles

158
Q

how are inactivated vaccines typically produced

A

virulent microbe is inactivated by chemicals or irradiation

159
Q

how are attenuated vaccines produced

A

virulent microbe grown under adverse conditions or passed through differenjt hosts until avirulent

160
Q

are inactivated or attenuated vaccines more stable

A

inactivated vaccines are more stable

161
Q

is the immune response stronger in an attenuated or inactivated vaccine

A

attenuated vaccine

162
Q

reverts to a virulent form; common in attenuated vaccines

A

reversion tendency

163
Q

a live virus was weakened by procedures such as heat treatment or by mutation

A

attenuated vaccine

164
Q

memory cell formation steps

A
  • apcs engulf pathogens at sites of infection
  • apcs present antigens on their surface on their surface and more into regional lymph nodes
  • in the lymph node, free antigens interact with B cells, APCss engage T cells; activated B cells differentiated into plasma cells and memory cells; CTL cells. are activated
  • plasma cells, memory cells, and CTLs leave the lymph node and enter the circulation
  • plasma cells and memory cells enter bone marrow, CTLs migrate to infection site
165
Q

a virus coated with what cannot attach to host cells

A

neutralizing antibodies

166
Q

activates lux transcription

A

luxR

167
Q

steps to autoinducer Acyl-homoserine synthesis

A
  1. the LuxI protein synthesizes an acyl homoserine lactone autoinducer (AI)
  2. AI diffuses into medium and accumulates
  3. at threshold concentration, AI diffuses into cell and binds LuxR, which activates lux transcription
168
Q

chemotaxis is regulated by

A

post translational protein modification

169
Q

alternating runs and tumbles result in

A

no directed movement

170
Q

when flagella rotate in one direction, what occurs

A

straight line movement occurs

171
Q

counterclockwise movement =

A

run

172
Q

clockwise movement =

A

tumble

173
Q

what happens when flagella change their direction of rotation

A

cell tumbles and randomly changes direction

174
Q

prolonged runs can move a bacterium

A

toward or away from a chemical

175
Q

initiated by chemoreceptor membrane proteins that detect chemicals in the environment

A

chemotaxis

176
Q

chemotaxis signaling relies on

A

PT regulation of Che proteins

177
Q

what type of movement is favored in the presence of an attractant

A

runs

178
Q

how can chemorecptors be desensitized?

A

via methylation

179
Q

methylates MCP

A

CheR

180
Q

sensor kinase, autophosphorylates itself and phosphorylates both CheY and CheB

A

CheA

181
Q

response regulator; controls direction of flagellar rotation

A

CheY

182
Q

response regulator; demethylates MCP

A

CheB

183
Q

dephosphorylates CheY-P

A

CheZ

184
Q

involved in transduction of signal from MCP to CheA

A

CheW

185
Q
  • small infectious agents that use host cell machinery to replicate
  • no organelles, no cytoplasm, no ribosomes
A

viruses

186
Q

complete infective form of a virus

A

virion

187
Q

a virion always contains which components

A
  • covering (capsid)
  • central core (nucleic acid)
188
Q

cannot reproduce outside their host cell, meaning that the parasite’s reproduction is entirely reliant on intracellular resources

A

intracellular obligate parasites

189
Q

how are viruses classified

A

via their genomes

190
Q

characteristics of viral genomes

A
  • 1K to 200K+ bases
  • can be linear or circular
  • can be a single molecule or segmented
191
Q

the ability of a virus to infect a particular cell, tissue, or host species

A

viral tropism

192
Q

recognizes viruses based on genome structure and replication strategy

A

Baltimore Classification System

193
Q

dsDNA viruses

A

group I viruses

194
Q

ssDNA viruses

A

group II viruses

195
Q

dsRNA viruses

A

group III viruses

196
Q

+ssRNA viruses

A

group IV viruses

197
Q

-ssRNA viruses

A

group V viruses

198
Q

RNA reverse transcribing viruses (retroviruses)

A

group VI viruses

199
Q

DNA reverse-transcribing viruses (pararetroviruses)

A

group VII viruses

200
Q

give virions their shape

A

capsid

201
Q

steps to foreign invaders triggering an adaptive immune response

A
  1. APCs engulf microbes at the site of infection, digest them, and present antigens on the AP surface
  2. free-floating antigens form the microbe bind to B cell receptors
  3. T cell-independent antigens trigger B cell differentiation into plasma cells
  4. plasma cells secrete antibodies
  5. APCs present antigens to helper T cells and cytotoxic T cells
  6. Tc cell becomes an activated cytotoxic lymphocyte (CTL)
  7. CTL circulates, finds, and destroys infected host cells
  8. some helper T cells help B cells respond to T cell-dependent antigens OR other helper T cells help Tc cells become CTLs
202
Q

methods of viral evolution

A
  • mutation
  • recombination
  • reassortment
203
Q

through reassortment of gene segments from very different strains

A

antigenic shift

204
Q
  • when multiple viruses with segmented genomes infect the same cell, they can swap segments in newly formed viruses
A

reassortment

205
Q

fusion of pieces of two separate viral genomes to create a new hybrid genome

A

recombination

206
Q

the gradual accumulation of mutations

A

antigenic drift

207
Q

viral polymerases lack

A

proofreading capability

208
Q

mutation rate is particularly high for

A

RNA dependent RNA polymerase

209
Q

why are antiviral drugs difficult to develop

A
  • antibiotics work b/c they target bacterial structures viruses don’t have
  • viruses use host cell machinery
  • few targets are unique to the virus
  • typically narrow spectrum
  • lack or reliable animal models
  • resistance develops very quickly
210
Q

why is the principle of selective toxicity complicated when targeting viruses

A

viruses use host cell machinery, and if you inhibit a host cell process, toxicity will be high

211
Q

make DNA from their RNA genome; use reverse transcriptase

A

group VI retroviruses

HIV

212
Q

carry viral polymerase in with their antisense genome

A

group 5 -ssRNA viruses

ebola, influenza, measles, mumps, rabies

213
Q

carry mRNA into the cell

A

group 4 +ssRNA viruses

Coronaviruses, Flaviviruses, Poliovirus

214
Q

types of viral capsids

A
  • filamentous/helical
  • tailed
  • icosahedral
  • asymmetrical
214
Q

if a plasma membrane surrounds the capsid, the virus is

A

enveloped

215
Q

how are viral envelopes acquired

A

from host cell membranes with viral proteins

216
Q

steps to the viral replication cycle

A
  1. attachment (to host cell)
  2. entry and uncoating of genome
  3. genome expression and protein production
  4. genome replication
  5. assembly of new viral particles
  6. exits host cell
217
Q

what does a successful virus need to be able to intitate infection

A

adhere to a host cell

218
Q

true or false:

host cell receptors vary between species

A

true

219
Q

what is the most important determinant of tropism

A

interaction between surface proteins and host cell receptors

220
Q

how do viruses enter the cell and release its genome

A
  • envelope fusion with the cell membrane
  • receptor-mediated endocytosis
221
Q

enzymes that are used for genome replication and transcription

A
  • DNA dependent DNA polymerase (I)
  • DNA dependent RNA polymerase (IV)
  • RNA dependent RNA polymerase (V)
  • RNA dependent DNA polymerase (VI)
222
Q

usually access the host nucleus and use host polymerases

A

typical group I viruses

Epstein Barr, Herpes Simplex, Varicella Zoster, HPV

223
Q
A
224
Q
A

Microbio (3 decks)

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