21.2 Virus Infections & Hosts

Question 1

Obligate intracellular parasites –

Answer 1

Viruses cannot reproduce outside host. Rely on host enzymes, ribosomes, ATP. Hijack cellular machinery to replicate. Cannot synthesize proteins, metabolize independently. Infect all life forms.

Question 2

Cytopathic effects

Answer 2

Virus-induced cellular changes. Includes:
cell lysis (cell rupture), apoptosis (programmed self-destruction)
Causes tissue damage, inflammation.
Used to diagnose viral infections.
budding (replicated virus leave cell)

Question 3

Lysis vs. apoptosis

Answer 3

Lysis: virus bursts host cell, releases virions.
Apoptosis: programmed cell death, limits viral spread. Some viruses delay apoptosis to increase replication.

Question 4

: Virus infection steps Check for accuracy

Answer 4

1) Attachment (binds receptor),
2) Entry (endocytosis/fusion), 2a) Uncoating (genome released) {this is not on pptx but in book},
3) Replication & Assembly (virions formed),
4) Release (lysis or budding).

Question 5

Lytic cycle

Answer 5

Virulent infection. Virus hijacks host, rapidly replicates, lyses cell. Produces immediate symptoms. Example: T4 bacteriophage.

Question 6

Lysogenic cycle

Answer 6

Virus integrates into host genome (prophage/provirus). Lies dormant, replicates with host. Can reactivate into lytic cycle. Example: Lambda phage, HIV latency.

Question 7

Prophage

Answer 7

Integrated viral genome in bacterial DNA. Passed to daughter cells during division. Can later activate lytic cycle.

Question 8

Attachment
(state number, fxn)

Answer 8

cell receptors bind to capsid proteins or envelope glycoproteins
-right receptor molecules req -> specific species or cell types they can infect

Question 9

Entry

Answer 9

(endocytosis/fusion

Question 10

Replication

Answer 10

(nucleic acid copied)

Question 11

Egress (Release)

Answer 11

(lysis or budding).

Question 12

Assembly

Answer 12

(virions formed)