Viruses

Question 1

Features of virus

Answer 1

• Not able to replicate outside host cell

- Have DNA or RNA enclosed in protein coat- nuceocaspid (and sometimes envelope)

Question 2

Components of virus

Answer 2

• Nucleic acid (DNA or RNA, single or double stranded, circular or linear, one piece or segmented)
• Structural proteins (determine symmetry, protect nucleic acid)
• Enzymes
• Glycoproteins (inserted into envelope, role in host/target cell infection)

Question 3

Nucleocapsid

Answer 3

Nucleic caspid and protein coat

Question 4

Host transmission routes

Answer 4

Oral, skin, droplet, sexual, trans-placental (vertical), directly (trauma, injection or bites etc.)

Question 5

Virus replication

Answer 5

Virus adsorbs to host cells via their receptor binding proteins.
Membranes fuse or virus enters cell via receptor-mediated endocytosis.
Caspid (protein coat) is shed to uncoat nucleic acid, which replicates to produce to synthesise more RNA and viral proteins. These are then assembled into nucleocaspids and released- either egress or budding)

Question 6

Cytolysis

Answer 6

Dissolution or destruction of cell

Question 7

Egress

Answer 7

Coming out/leaving cell

Question 8

Budding

Answer 8

Expulsion and release of virus progeny using cell membranes to create viral envelope