Chapter 9

Question 1

General differences between cells, viruses, viroids, and prions

Answer 1

Cells have DNA and RNA and can replicate
Viruses, viroids and prions cannot replicate on their own (obligate intracellular parasite)
Viruses, viroids and prions do not contain organelles, cytoplasm, nor a nucleus
Viruses have DNA and/or RNA

Question 2

Viroids

Answer 2

Only have RNA – circular RNA
do not contain capsid
pathogens to plants

Question 3

Prions

Answer 3

Only have proteins
Single protein called PrP

Question 4

Name of the viral particle depending on location in respect the cell

Answer 4

Virus: infecting the cell
Virion: outside of the cell or recently made to be release

Question 5

viral components

Answer 5

nucleic acid, capsid, envelope, spikes

Question 6

Nucleic acid

Answer 6

DNA/RNA, single or double stranded. linear, circular, or fragmented.

Question 7

Capsid

Answer 7

composed of many capsomeres. Determine the shape of the virus. Play key role in virus attachment

Question 8

Envelope

Answer 8

bilayer membrane (lipids, proteins, carbohydrates). As they bud out of cells they obtain an envelope. Not all cells have it.

Question 9

Spikes

Answer 9

projections to attach virions to specific receptors sites on host

Question 10

viral host range

Answer 10

Spectrum of hosts that a virus can infect
One or more host / cell type

Question 11

Viral specificity

Answer 11

Specific kind of cells a virus can infect
Only skin cells
Salivary glands
Fetal tissue

Question 12

What could cause viruses to start emerging?

Answer 12

Mutations
Reservoirs - Healthy organism harboring an infectious agent that is available to infect another host
Vectors
Easy travel
Population density

Question 13

5 steps for viral replication – know the order and understand what happens

Answer 13

absorption, penetration, biosynthesis, maturation, release

Question 14

Absorption

Answer 14

the attachment of the virion to host cells

Question 15

Penetration

Answer 15

the entry of viruses into host cells

Question 16

Biosynthesis

Answer 16

synthesis of new nucleic acid molecules, capsid, proteins, and other viral components within host cells

Question 17

Maturation

Answer 17

the assembly of newly synthesized viral component into complete virions

Question 18

Release

Answer 18

the departure of new virions from host cells. Release usually, but not always, kills (lyses) host cells

Question 19

2 types of cycles

Answer 19

Lytic/virulent
Lysogenic/non-virulent
- Longer in penetration. It does not leave the DNA and it reproduces with the cell.
- It can move to the biosynthesis step at any time.

Question 20

Viral effects – what do they mean in relationship with a virus

Answer 20

Teratogenic - Teratogenesis is the induction of defects during embryonic developmentWhen the organism is only a few cells, damage to any of those cells can interfere with development. Cytomegalovirus, herpes simplex virus, rubella. Most of the defects are neurological, enlarged spleens, liver damage, jaundice

Question 21

Cancer

Answer 21

DNA sequence of a gene changes - viral DNA is within it

Question 22

Viral treatments – compare these

Answer 22

Medication - Antiviral drugs are difficult to develop because of viruses’ high mutation rate. Teach your immune system
Vaccines - Vaccines “teach” your immune system to recognize a virus