viruses

Question 1

what are viruses?

Answer 1

small particles that infect living cells to replicate

Question 2

are viruses alive?

Answer 2

classified as non-living

Question 3

where are viruses said to have originated from?

Answer 3

fragments of genetic material

Question 4

why do viruses blur the line between life and not life? (name 4/8 reasons)

Answer 4

do not maintain homeostasis
is not made of cells, no organelles
has different levels of cellular organization (nucleic acids, capsids)
does not grow
kind of reproduces - replicates
unknown whether responds to stimuli
uses host cell’s energy and material
mutates and evolves, adapts to surroundings

Question 5

what are capsids made out of?

Answer 5

capsomere

Question 6

what is a viron?

Answer 6

a singular virus particle

Question 7

what comprises a virion?

Answer 7

genes and capsid

Question 8

what is a capsid?

Answer 8

a protective protein shell

Question 9

why don’t antibiotics work on viruses?

Answer 9

viruses don’t perform basic life processes, the medication targets those processes in bacteria

Question 10

how does antiviral medication work?

Answer 10

interferes with replication/viral synthesis, binding + release

Question 11

what is a prion?

Answer 11

an abnormally folded, infectious, brain protein

Question 12

how are prions thought to be spread?

Answer 12

food

Question 13

what do prions cause?

Answer 13

degenerative brain diseases (mad cow, kuru)

Question 14

what is a viroid?

Answer 14

a small infectious particle that infects plants

Question 15

describe a viroid

Answer 15

no protein coat, only short stretches of RNA

Question 16

what stores a virus’s genetic information?

Answer 16

nucleic acid core

Question 17

describe structural differences between DNA and RNA

Answer 17

both made of phosphate + ribose + nitrogenous base, RNA has one more OH

Question 18

what is a retrovirus?

Answer 18

virus which originally has a genome of RNA, but is reverse transcribed into DNA in the host

Question 19

what is involved in reverse transcription?

Answer 19

reverse transcriptase, cDNA, DNA polymerase

Question 20

what is cDNA?

Answer 20

single-stranded DNA made from reverse transcribing RNA

Question 21

what is a provirus?

Answer 21

virus that has incorporated its genome into the host cell

Question 22

how is the host cell recognized? (structure)

Answer 22

spike protein/protein spike

Question 23

on which viruses are envelopes found?

Answer 23

animal viruses

Question 24

what (on the envelope) helps the virus binds to the host cell

Answer 24

viral proteins

Question 25

what structure is unique to the bacteriophage?

Answer 25

tail made of: tube sheath, tail fibres, end plate, spikes

Question 26

what does the tail of a virus do?

Answer 26

shortens + contracts then injects the nucleic acid core into the cell

Question 27

how do plant viruses enter?

Answer 27

tiny rips in cell wall

Question 28

how do animal viruses enter?

Answer 28

endocytosis

Question 29

name the 4 step process for viral replication

Answer 29

attachment, synthesis, assembly, release

Question 30

what are virulent phages?

Answer 30

phages that only replicate through lytic cycles

Question 31

what are temperate phages?

Answer 31

phages that alternate between lytic and lysogenic cycles

Question 32

what occurs during a lytic cycle at the end? (hint: to the cell)

Answer 32

lysis

Question 33

what occurs during a lysogenic cycle?

Answer 33

nothing of note, genes do not take over the cell immediately

Question 34

what does a lysogenic cycle manifest as for the body overall? (think covid)

Answer 34

asymptomatic periods with occasional flare ups

Question 35

what is another word for viruses in the lysogenic cycle?

Answer 35

dormant - virus co-exists/is integrated into bacterial DNA

Question 36

what happens if a dormant virus is triggered?

Answer 36

becomes virulent again, moves to lytic cycle

Question 37

what can trigger a dormant virus?

Answer 37

DNA damage, temperature change, loss of necessary nutrients

Question 38

how can bacteriophages be helpful? (hint: our bodies)

Answer 38

kills harmful bacteria in our mucus

Question 39

what is gene therapy?

Answer 39

process in which viruses are used as vectors to carry altered DNA to infected cells

Question 40

what are vectors?

Answer 40

carriers of DNA/nucleic material into another cell

Question 41

how do viral-vector vaccines work?

Answer 41

another virus is weakened and genetically engineered such that it can produce viral proteins of another virus in the body

Question 42

how do nucleic-acid vaccines work?

Answer 42

uses genetic information for a viral protein that triggers an immune response

Question 43

what is the purpose of vaccines?

Answer 43

build T and B lymphocytes that will remember how to fight the virus (recall: antibody graph w 2 curves)

Question 44

how do viroids replicate?

Answer 44

host cell makes copies of the viroid - no instructions for protein synthesis