7.7 Viruses Flashcards
are viruses alive?
not considered alive bc inability to replicate on their own, but can replicate themselves so classified same way as living things
virus
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
if viral genome composed of ss RNA?
- genome replicated codes for reverse transcriptase
reverse transcriptase
uses RNA as template strand to synthesize complementary DNA
retrovirus
virus that uses reverse transcriptase for replication
functions of reverse transcriptase
- 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
virus as vector
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)