Intro to viruses

Question 1

two forms of a virus

Answer 1

• virion (infetious) (metabollically inert

- replicative

Question 2

components of a virus

Answer 2

• envelope
• genome
• matric
• capsid
• nucleoprotein

Question 3

how can a capsod be constructed

Answer 3

• it can only contain a certain amount of DNA
• must be constructed of one or only a few proteins repeated many times
• capsids must have symmetrical structure
• two types of symmetry are obsevered

Question 4

types of symmetry

Answer 4

• helically symmetrical

- icosahedral

Question 5

what can the viral genome be composed of

Answer 5

• DNA: ss, ds, circular single

- RNA: linear plus stranded, linear minus stranded, segmented minus stranded, segmented double strnaded

Question 6

how to produce different viral proteins

Answer 6

• polyprotein
• segemented genome
• nested mRNA’s
• differential splicing

Question 7

adsorption

Answer 7

interaction between virus protein and cell surface receptors

Question 8

penetration

Answer 8

• receptor mediated endocytosis ot direct interaction at the cell surface
• fucion of the virus and cell membranes

Question 9

uncoating

Answer 9

• release of nuceic acid with or without enymes

- allows for expression

Question 10

early events

Answer 10

• depend on crus group

- prepare for nucleic acid replication

Question 11

late events

Answer 11

• nucleic acid replication
• virion protein synthesis
• virion assembly and release

Question 12

polyprotein

Answer 12

-a linear DNA is transcribed and then the protein is split later down the road

Question 13

segmented genome

Answer 13

-each segment is a different protein

Question 14

nested mRNA’s

Answer 14

one transcript is trancribed in different segments in order to get different proteins proteins

Question 15

differential slicing

Answer 15

-trancripts made and spliced differently

Question 16

dsDNA transcription

Answer 16

• early mRNA synthesis and viral protein synthesis
• uses RNa pol and cell ribosomes
• papillomavirus

Question 17

+RNA virus transcription

Answer 17

• immediate viral protein synthesis
• cell ribosomes used
• picornavirus (polio)

Question 18

-RNA minus transcription

Answer 18

• mRNA synthesis and viral protein synthesis
• virion enzyme used to do so, (transcriptase)
• translated on cellular ribosomes myxovirus

Question 19

retro virus transcription

Answer 19

• plus strand RNA
• virion contains the reverse trranscriptase so it can synth its own DNA
• this is the initial event after infection
• plus RNa gets converted to dsDNA

Question 20

transfection

Answer 20

• genomes from a virus are introduced into cells by one of a variety of tricks
• with viruses that do no require a virion trancriptase (DNA/+RNA), a complete infection cycle can be done this way