Viruses And Other Acellular Entities Exam 3

Front 1

Lytic Cycle (4 steps)

Back 1

Virus attaches to cell; Viral DNA forms a circle; New viral DNA and proteins are produced and assembled; Cell lysis, releasing viruses

Front 2

Lysogenic Cycle

Back 2

Same as Lytic except viral DNA replicated multiple times before separating from bacteria chromosome...initiating a lytic cycle

Front 3

Start of viral replication

Back 3

Phage absorbs to bacteria cell wall; injection of phage DNA probably occurs within seconds of adsorption

Front 4

1 minute into replication

Back 4

Host DNA, RNA, and protein synthesis are totally turned off...early gene

Front 5

2 minutes into replication

Back 5

Synthesis of first mRNA begins...early gene

Front 6

3 minutes into replication

Back 6

Degradation of bacterial DNA begins...early gene

Front 7

5 minutes into replication

Back 7

Phage DNA synthesis is initiated...early gene

Front 8

9 minutes into replication

Back 8

Synthesis of "late" mRNA begins...late gene

Front 9

12 minutes into replication

Back 9

Completed heads and tails appear...late gene

Front 10

15 minutes into replication

Back 10

First complete phage particle appears...late gene

Front 11

22 minutes into replication

Back 11

Lysis of bacteria; release of about 300 progeny phage...late gene

Front 12

Theta replication

Back 12

Bidirectional; uses host enzymes; used to produce a few copies before starting rolling circle

Front 13

Rolling circle replication

Back 13

Indefinite; forms concatemers

Front 14

Choice to go lytic of lysogenic

Back 14

Influenced by internal host environment; slowly growing cells induce lysogeny cycle; fast growing cells induce lytic cycle

Front 15

Latency involves...

Back 15

integration of the viral genome into the host genome

Front 16

In the integrated state...

Back 16

viral genomes don't actively replicate themselves, but are passively replicated every time the host chromosome is replicated

Front 17

A latent bacterial virus (phage) referred to as

Back 17

temperate phage

Front 18

Prophage

Back 18

A viral (phage) genome integrated in a host chromosome

Front 19

Lysogen

Back 19

a host cell carrying a prophage

Front 20

Latent viruses make host cells...

Back 20

immune to subsequent infection by a similar virion

Front 21

Varicella Zoster virus

Back 21

Primary infection causes chickenpox; can be reactivated after latency causing shingles; One of eight herpesviruses infecting humans; reactivation often caused by stress to the host cell

Front 22

Latent viruses can be...(2)

Back 22

Induced (phages) or reactivated (animal viruses)

Front 23

Latency is a strategy for..

Back 23

intergenerational virus transmission

Front 24

RNA Viruses...two types

Back 24

Positive (+) strand RNA viruses

Negative (-) strand RNA viruses

Front 25

Negative strand RNA virus replication is

Back 25

complex and typically occurs in the cytoplasm ( with the exception of influenza and retrovirus which occur in the host cell nucleus)

Front 26

All RNA virus assembly occurs in...

Back 26

The cytoplasm

Front 27

The (+) strand RNA virus genome acts as a...

Back 27

mRNA template and produces its own replicase

Front 28

A single-stranded (-) ssRNA virus genome brings a...

Back 28

replicase protein when it enters the host cell

Front 29

Retroviruses use a...

Back 29

reverse transcriptase (RT) replicase to convert their ss-RNA genome into a DNA template to produce progeny viruses

Front 30

Viral multiplication requires a...

Back 30

strictly ordered synthesis of viral proteins

Front 31

Most viral genomes encode proteins whose only function is to...

Back 31

regulate the timing of synthesis of other proteins

Front 32

Expression of viral early genes direct genome replication proteins occurs first followed by...

Back 32

late genes direction capsid and/or virion assembly proteins

Front 33

Simple virions like the Tobacco Mosaic Virus...

Back 33

self-assemble in the plant cytoplasm

Front 34

Complex virions like poxviruses...

Back 34

express packaging enzymes direction virion assembly

Front 35

Animal and plant viruses translate...

Back 35

polyproteins

Front 36

Virus envelopes are obtained by...

Back 36

budding; nucleocapsid binds to viral envelope proteins in the membrane

Front 37

The continues budding process of enveloped virions allows for...

Back 37

Release of enveloped virions and limited damage to the host cell

Front 38

Release of non-enveloped virions is typically by...

Back 38

host cell lysis; completely destroys host cell

Front 39

Viroids consist of...

Back 39

non-encapsulated, or naked, RNA; infective for several species of plants

Front 40

Viroid RNA is not translated--

Back 40

it interferes with host translation

Front 41

viroids are replicated by

Back 41

the tolling circle mechanism

Front 42

viroid RNAs range from

Back 42

250-400 bases in length

Front 43

viroids are transmitted from plant to plant by...

Back 43

insects

Front 44

viroids move within plant through...

Back 44

plasmodesmata

Front 45

Viroids cause...

Back 45

disease

Front 46

Prions are...

Back 46

infectious conformations of the mammalian bran protein PrP--arising spontaneously

Front 47

Prions replicate by...

Back 47

catalyzing their conformational change in other PrP proteins

Front 48

Prion replication causes...

Back 48

Spongiform encephalopathy; mad cow disease

Front 49

Variant Creutzfeldt or Jakob Disease

Back 49

Spongiform encephalopathy proteins form in the brain