lecture 5

Question 1

plant, animal, human and bacteria viruses

Answer 1

TMV, foot and mouth, yellow fever, bacteriophage

Question 2

what are viruses (4)

Answer 2

cannot survive without a host
rely completely on biosynthetic machinery cell multiply
infect all types of cells (animal, plant, bacteria)
most abundant bio entities on earth 10^31

Question 3

what does a virion consist of

Answer 3

genetic material
capsid protein coat
=nucleocapsid
(envelope of lipids)

Question 4

3 types of viral symmetry

Answer 4

helical, icosahedral, complex (capsomeres, protomers)

Question 5

3 types of viral genome organisation

Answer 5

linear, circular, segmented

Question 6

virus life cycle

Answer 6

1. attachement of viron to host cell
2. entry of nucleocapsid
3. synthesis of viral components
4. assembly of viral components into progeny virions
5. release of progeny virions from host cell

Question 7

lytic cycle

Answer 7

1. phage DNA circularizes
2. phage DNA and proteins are synthesised and assembled
3. cell lyses releasing phages
4. phage injects its DNA

Question 8

lysogenic cycle

Answer 8

1. phage DNA circularizes
2. phage DNA integrates into bacterial chromosome
3. prophage is copied with bacterial chromosome
4. many cell divisions- daughter cells with prophage

Question 9

RNA enveloped virus HIV retrovirus cycle

Answer 9

1. Glycoproteins bind to surface of cells and membrane fuses to cell membrane releasing contents of virus
2. Reverse transcriptase converts RNA to DNA
3. DNA can then be incorporated into host DNA provirus- latent
4. DNA transcripted and translated to created replicated RNA and viral proteins- enveloped glycoproteins.
5. budding from the cell- capsid encapsulates DNA and virus takes some of host membrane and leaves the cell