viruses

Question 1

virus

Answer 1

non cellular infectious agent

Question 2

characteristics of all viruses

Answer 2

1) protein coat wrapped around DNA or RNA (protein and nucleic acid)
2) cannot reproduce by itself (not a living thing)
3) rapid replication= rapid evolution
new phenotypes/protein coats

Question 3

why are viruses not living things

Answer 3

not cells
cant reproduce
can have single stranded DNA and double stranded RNA

Question 4

classification of viruses based on

Answer 4

type of protein coat (capsid)
nucleic acid type (RNA or DNA)
Envelope presence

Question 5

size ranges for viruses

Answer 5

18nm-350nm

Question 6

simple virus

Answer 6

1. hollow protein shell
2. protruding molecules that bind to host cell
   tricks cell into taking it in through the glycoprotein

Question 7

complex virus

Answer 7

more parts
1. head, neck, tail
2. bacteriophage
injects DNA into host

Question 8

enveloped virus

Answer 8

capsid surrounded
by layer of membrane
glycoproteins attach to receptors and convince to let in. Mail themselves in host cell membrane so makes them hard to find

Question 9

nucleic acids for virus

Answer 9

Double/single stranded DNA
Double/single stranded RNA
Largest segment containing 4 genes

Question 10

RNA virus =

Answer 10

retrovirus

Question 11

RNA can be

Answer 11

used as a template to make viral mRNA (use the host to make copies) or copied into DNA by reverse transcriptase (converts viral RNA -> DNA)

Question 12

why do retroviruses mutate faster than DNA virus

Answer 12

because RNA polymerase and reverse transcriptase have no proofreading

Question 13

enveloped viruses makeup and process

Answer 13

wrapped in a layer of host cell membrane
Intermembrane viral glycoproteins protruding out of membrane bind to host cell (tricks host)
Protovirus DNA integrates by integrase into host DNA
New viruses can leave host cell without lysis. (makes host cell make copies and then releases)

Question 14

HIV=

Answer 14

enveloped retrovirus

Question 15

HIV virus binds to

Answer 15

cellular receptors on white blood cells called T cells

Question 16

T cells

Answer 16

immune cells so immune deficiency

Question 17

HIV envelope retrovirus process

Answer 17

Protovirus integrates into T-cell DNA

We can not get to the protovirus in the nucleus so very difficult to treat

Question 18

what is HIV positive but no AIDS

Answer 18

when the protovirus remains inactive in the T-Cells for years. Can be activated when immune system low

Question 19

Viral Multiplication(component assembly model)

Answer 19

attachment, penetration,
replication and protein synthesis,
assembly,
release

Question 20

attachment

Answer 20

virus chemically recognizes host and locks on

Question 21

penetration

Answer 21

entire virus or virus DNA/RNA enters host cell

Question 22

Replication & protein synthesis

Answer 22

of Viral genes makes viral proteins and DNA/RNA

Question 23

assembly

Answer 23

new viruses put together into capsid

Question 24

release

Answer 24

new viruses leave host cell either burst out through lysis or just leave through exocytosis

Question 25

viral multiplication lytic pathway

Answer 25

steps proceed rapidly and end in lysing of the cell, bursting.

Question 26

lysogenic pathway

Answer 26

Viral DNA integrated into host DNA Viral DNA copied each time host cell divides Latent period Stimulus (depresses immune system) causes switch to lytic cycle and symptoms appear can give new properties to host cells

Question 27

latent period

Answer 27

= no symptoms but more and more host cells are becoming infected

Question 28

example of lysogenic pathway

Answer 28

type 1 herpes simplex, cold sores

Question 29

example of giving new properties to host cell in lysogenic pathways

Answer 29

cut into cell so can cut certain genes, results in Increased pathogenicity (worse symptoms) in bacteria

Question 30

transduction

Answer 30

Bacterial genes transferred from one bacteria to another via virus particles

Question 31

Viral proteins mutate rapidly due to

Answer 31

replication & transcription errors rapid reproduction rates obtaining genes from other viruses that occupy the same host cell – ex: bird flu and swine flu

Question 32

why do we need new shots for viruses

Answer 32

mutate rapidly so need New shots to help immune system recognize the changed virus

Question 33

prions

Answer 33

proteins in nervous system

Question 34

infectious prions

Answer 34

Infectious prions are misfolded Misfolded prions deposit in brain Misfolded prions can cause normal prions to misfold Infectious Prions not destroyed by cooking!

Question 35

mad cow disease =

Answer 35

BSE

Question 36

beef infected with BSE can cause

Answer 36

vCDJ in humans, cause human prions to misfold

Question 37

where is mad cow found in

Answer 37

Brains and spinal tissue of a cow