7.7 Viruses

Question 1

are viruses alive?

Answer 1

not considered alive bc inability to replicate on their own, but can replicate themselves so classified same way as living things

Question 2

virus

Answer 2

one or more nucleic acid molecules surrounded by protein coat (capsid)
- some viruses also surrounded by envelope created when virus leaves host cell and part of cell membrane wraps around virus

Question 3

if viral genome composed of ss RNA?

Answer 3

• genome replicated codes for reverse transcriptase

Question 4

reverse transcriptase

Answer 4

uses RNA as template strand to synthesize complementary DNA

Question 5

retrovirus

Answer 5

virus that uses reverse transcriptase for replication

Question 6

functions of reverse transcriptase

Answer 6

• copies viral RNA to make complementary molecule of ss RNA using cell’s supply of materials
• directs synthesis of second DNA strand complecmentary to first and integrase incorporates reverse transcribed ds DNA into host cell genome
  transcription of viral DNA = viral RNA that serces as genome for new virus and can be translated to make viral proteins

Question 7

virus as vector

Answer 7

ability of virus to enter cell and use cell’s replication enzymes gives method for inserting new genetic material into existed cells (insulin in safflower seeds)