Chapter 19: Viruses

Question 1

Virus genetic material

Answer 1

single stranded (RNA) or double stranded (DNA)

may be linear or circular

Question 2

Virus

Answer 2

infectious particle made of DNA packed in a protein coat (called a capsid); sometimes they have a membrane

Viruses are not cells; they hijack the ribosomes, tRNAs, amino acids, ATP, and other molecules of host cells

Question 3

Virus cycle

Answer 3

1. Entry and uncoating
2. replication
3. transcription (hijacking) and manufacture of capsid protein (inside the host cell)
4. self-assembly of new virus particles & eruption from the host cell

Question 4

Virulent phages

Answer 4

phages that only use the lytic cycle resulting in death of the host cell(s)

Question 5

Phage reproductive cycle types (2)

Answer 5

Lytic cycle

Lysogenic cycle

Question 6

Restriction enzymes

Answer 6

Defense mechanisms bacteria use to combat phages

enzymes ID and cut up viral DNA

Question 7

Viral envelope

Answer 7

Outer layer of some viruses that contains molecules from the virus and from the host cell

Question 8

Phage lytic cycle

Answer 8

1 of 2 types of phage reproductive cycles

Cycle used by “virulent phages”

causes host cell to die (because it bursts out of the cell once all the baby viruses are too big to fit inside anymore)

Question 9

Temperate phages

Answer 9

phages that can use the lytic cycle and/or the lysogenic without always resulting in death of the host cell(s)

Question 10

Lysogenic cycle

Answer 10

1 of 2 types of phage reproductive cycles

does NOT kill the host cell because its DNA lives in the host cell and gets spread as the cell divides into dgt cells

But environmental cues can cause the virus to switch to a lytic cycle, instead

Question 11

Prophages

Answer 11

what you call a host cell that has viral DNA from a lysogenic cycle inside it

Question 12

Host range

Answer 12

The limited number of cells that a virus can infect

Question 13

Capsomere

Answer 13

subunits used to build virus’ capsids (protein coats)

Question 14

5 stages of lytic cycle

Answer 14

1. attachment (of virus onto host cell)
2. insertion of virus DNA & degradation of host DNA
3. Synthesis of viral genomes & proteins
4. Self-assembly (gee, thanks)
5. Release