FINAL CONSOLIDATION Flashcards
1
Q
Why are virus not considered living?
A
- Acellular; lack cellular components
- Do not carry out metabolic processes outside a host cell
- All cells contain double-stranded DNA genome, but viruses have either DNA/RNA genomes, which can be single/double-stranded
- Incapable of movement
2
Q
Explain why viruses are obligate intracellular parasites
A
they lack cellular machinery and cannot replicate independently and relies on host cell machinery for replication
3
Q
antigenic shift
A
- More than one strains of virus infect a single cell in an organism when the new viral particles are assembled
- there could be random assortment of RNA segments from different strains
- giving rise to novel strain
4
Q
Describe antigenic drift
A
- Mutation in the genetic sequence in the viral RNA segments
- can result in a change in the protein structure
- human immune system is unable to recognise proteins on surface of the virus
- lacks immunity to defend against it
