virsuses Flashcards
lambda phage virus
capsid with head and tail
double stranded DNA
transcribed into host cell by mRNA
infects bacterium
Tobacco Mosaic Virus (TMV)
capsid with spiral of polypeptides
single stranded RNA
transcribed into host cell from mRNA
infects plants
Ebola
protein capsid
single stranded RNA
transcribed into host cell from mRNA
infects several types of human cell
HIV
capsid surrounded by phospholipid and glycoprotein envelope
single stranded RNA transcribed into single stranded DNA
infects macrophage and T helper cells of humans
action of antivirals
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
how skin prevents viruses entering
keratin
skin acts as a physical barrier
does not have complementary receptors
why viruses are not affected by antibiotics
not living cells
don’t have cell walls
why there is a delay in cell lysis from initial infection of a cell by lambda phage virus
viral DNA enters host
new DNA synthesised
protein synthesises must occur
to form more viruses
only virus to contain DNA
lambda phage
why an electron microscope, rather than a light microscope is used to take images of viruses
resolution is higher
due to shorter wavelength of electrons
Describe the lytic cycle of a virus
viral proteins made
virus multiplies until cell lysis
State what is meant by the term latency