Viruses

Question 1

virus

Answer 1

sub microscopic infectious agent only capable of producing within a host cell

Question 2

are viruses cellular

Answer 2

no, have. no cytoplasm, membrane bound organelles or cell membrane

Question 3

are viruses alive?

Answer 3

living: shaped by natural selection, invokes immune response

non-living: do not fit the criteria for life, are not composed of cells, no metabolism, ONLY reproduce in a host cell,

Question 4

do antibiotics work against viruses

Answer 4

no, antivirals do: some viruses don’t kill the host cell and remain in lysogeny

Question 5

what are virus genes made out of

Answer 5

DNA and RNA

Question 6

Baltimore classification system classifies viruses based on:

Answer 6

1) type of nucleic acid (dna/rna)
2) single or double stranded
3) whether or not they use reverse transcriptase (work backwards from RNA to DNA)

Question 7

VIRUS LYTIC CYCLE

Answer 7

1) attachment: virus attaches to cell membrane/cell wall of the host
2) penetration: virus must enter the cell through cell membrane fusion or endocytosis
3) uncoating: protein coat is worn away exposing the viral genome
4) replication and assembly: the viral genome takes over the hosts machinery and creates more viruses
5) lysis: new virus particles rupture forth from the host cell

(occurs in the cytoplasm)

Question 8

LYSOGENIC CYCLE

Answer 8

-viral DNA enters and becomes part of the host cells chromosomes
-now the host cell has the viral DNA forever (viral dna=provirus)
a provirus can invade a cell but not kill it

(enters host cell chromsome, genes aren’t activated until later in some cases)

Question 9

DNA VIRUSES

Answer 9

-usually infect a host through an encounter with the virus

-herpes, smallpox, chickenpox, etc.

-same genetic material as humans, after dna is inserted there are no extra steps for incorporation into our nuclei

Question 10

RNA VIRUSES

Answer 10

use rna as genetic material/intermediate to replicate

ex. rubella virus

Question 11

Reverse Transcripting Viruses

Answer 11

• these concert RNA into DNA and incorporate it into a host cell

-some viruses need to convert RNA to DNA: retroviruses because it works backwards (RNA TO DNA INSTEAD OF DNA TO RNA (normal))

-EX. HIV

Question 12

Bacteriophage

Answer 12

-type of virus that infects bacteria
- bacteriophage=bacteria eater
- attaches itself to a susceptible bacterium and infects a host cell, it hijacks the cellular machinery to prevent it from reproducing and instead forces the cell to produce viral components

Question 13

virulence

Answer 13

ability of a virus to cause disease

Question 14

how have viruses been used

Answer 14

• study basic mechanisms of molecular biology (dna replication, protein synthesis, etc.)
• genetic modification
• virotherapy: using viruses to treat bacterial diseases and some forms of cancer
• also being used as biological insecticides

Question 15

applications of viruses

Answer 15

• currently being used in nanotechnology to stop or start sequences needed in host cells
• biological weapon lol
• bacteriophages=used to fight superbugs

Question 16

how are viruses spread

Answer 16

vectors- animals
airborne- droplets from coughing or sneezing spread through the air
direct contact- infected person touching a surface and someone else touching the same surface
fecal oral: contaminated hands, food, water, etc.
sexually transmitted- direct transfer of bodily fluids

Question 17

how do viruses reproduce

Answer 17

lytic and lysogenic cycle

Question 18

structure of a virus

Answer 18

• a single molecule of nucleic acid surrounded by a protein coat, the capsid
• the capsid and its enclosed nucleic acid together constitute the nucleocapsid.
• In some of the more complex viruses the capsid surrounds a protein core