virsuses

Question 1

lambda phage virus

Answer 1

capsid with head and tail
double stranded DNA
transcribed into host cell by mRNA
infects bacterium

Question 2

Tobacco Mosaic Virus (TMV)

Answer 2

capsid with spiral of polypeptides
single stranded RNA
transcribed into host cell from mRNA
infects plants

Question 3

Ebola

Answer 3

protein capsid
single stranded RNA
transcribed into host cell from mRNA
infects several types of human cell

Question 4

HIV

Answer 4

capsid surrounded by phospholipid and glycoprotein envelope
single stranded RNA transcribed into single stranded DNA
infects macrophage and T helper cells of humans

Question 5

action of antivirals

Answer 5

prevent viral replication
by preventing viral RNA being incorporated to host DNA
by reverse transcriptase
and integrase
so viral DNA is not made from viral RNA

Question 6

how skin prevents viruses entering

Answer 6

keratin
skin acts as a physical barrier
does not have complementary receptors

Question 7

why viruses are not affected by antibiotics

Answer 7

not living cells
don’t have cell walls

Question 8

why there is a delay in cell lysis from initial infection of a cell by lambda phage virus

Answer 8

viral DNA enters host
new DNA synthesised
protein synthesises must occur
to form more viruses

Question 9

only virus to contain DNA

Answer 9

lambda phage

Question 10

why an electron microscope, rather than a light microscope is used to take images of viruses

Answer 10

resolution is higher
due to shorter wavelength of electrons

Question 11

Describe the lytic cycle of a virus

Answer 11

viral proteins made
virus multiplies until cell lysis

Question 12

State what is meant by the term latency