virus 1

Question 1

virus definition

Answer 1

biological entitiy consists of protein and nucelic acids, non cellular, no ribosomes, no orgnaelles, needs living cells to reproduce

Question 2

virus structure

Answer 2

50%-90% protein- forms capsid, capsid protects nuc acid, allows recog of host cell

nuc acid is DNA/RNA
single stranded/ double
circular/ linear

4-2500 coding genes

Question 3

types of viruses

Answer 3

isometric- lots of proteins
enveloped- proteins embedded
bacteriophage- only infects bacteria
viroids- circular, single stranded, no protein coding genes

Question 4

regressive theroy

Answer 4

descend from free living organisms, become parasitic and lose functions
BUT huge gap between virus and parasite

Question 5

escape theory

Answer 5

genetic material escaping from larger organisms genome
BUT doesnt explain virus structure

Question 6

ancient theory

Answer 6

go back to self replicating molecules in pre- cellular world
explains the difference between viruses and cellular life
BUT doesn’t explain how early viruses replicated without hosts

Question 7

definition of life

Answer 7

1. metabolism
2. homeoststis
3. response to stimuli
4. growth
   virus doesnt have
5. organisation
6. reproduction
7. evolution
   virus does have