L25

Question 1

viruses are _ _ _ - rely

on host _ _ to reproduce

Answer 1

obligate intracellular parasites

biosynthetic machinery

Question 2

(virions)

Answer 2

when not inside an infected
cell, viruses exist as
independent particles

Question 3

Simplest viruses encode_
proteins.
Most encode _ proteins
compared to humans (_)

Answer 3

4
100-200
~20 000)

Question 4

virions consist of (3)

Answer 4

double or single stranded DNA
or RNA
• a protein coat (capsid)
• lipid envelope

Question 5

lipid

envelope

Answer 5

derived from the host
cell which, like the capsid, may
contain antigenic glycoproteins

Question 6

virion size

Answer 6

~1/100th the size of the average

bacterium

Question 7

•Viral range

Answer 7

group of cell types

(or species) that a virus can infect.

Question 8

bacteriophage.

Answer 8

•Virus that infects only bacteria

Question 9

animal viruses or plant

viruses.

Answer 9

•Viruses that infect animals or plants

Question 10

•Most animal viruses to do not cross _, and some only infect closely related _ (ie humans and primates for poliovirus)

Answer 10

•Most animal viruses to do not cross phyla, and some only infect closely related species (ie humans and primates for poliovirus)

Question 11

•Viruses can be classified based on the shape of their

Answer 11

capsid

Question 12

capsid shapes

Answer 12

(helical, icosahedral, complex)

Question 13

pathogenicity

Answer 13

Ability of viruses to cause disease

Question 14

virulence.

Answer 14

• degree of pathogenicity

Question 15

latency.

Answer 15

Some viruses can remain dormant in organisms

Question 16

eg of latent viruses

Answer 16

varicella zoster (chicken pox,
shingles)

Question 17

carriers

Answer 17

• People chronically infected are called carriers and serve as reservoirs of infectious virus

Question 18

“Life” cycle of viral replication:

Answer 18

absorption,

penetration, replication, release

Question 19

Surface of viruses have __ that bind to receptor protein on host cell. _ determines the _ range of a virus and begins the infection process (i.e. HIV and
CD4).

Viral _ or _ crosses the plasma membrane to the cytoplasm or nucleus

Once inside, viral DNA or RNA interacts with host _ _ _ DNA or RNA into viral protein

newly synthesized _ particles are released to continue infection cycle

Answer 19

Surface of viruses have proteins that bind
to receptor protein on host cell. Interaction
determines the host range of a virus and
begins the infection process (i.e. HIV and
CD4).

Viral DNA or RNA crosses the plasma
membrane to the cytoplasm or nucleus

Once inside, viral DNA or RNA interacts
with host machinery for translating DNA or
RNA into viral protein

newly synthesized virion particles are
released to continue infection cycle