Theme A: A2 Cells - A2.3 Viruses Flashcards
Capsid
The protein shell that encloses the genetic material of a virus. It protects the viral genome and facilitates its delivery into host cells during infection.
Host cell
the cell used by a virus to carry out its metabolic and reproductive functions.
Obligatory intracellular parasite
(applies to all viruses) means they rely on living host cells to multiply and to carry out the metabolic functions required to exist
Virion
A virion is a fully-formed virus particle that is capable of infecting a host cell.
Lysis
The breakdown or destruction of a cell, often due to the rupture of its membrane, releasing its contents. In this chapter, lysis is used in the lytic cycle which ruptures the host cell’s cell membrane by an enzyme called lysozyme.
Lysis only occurs after production of virions.
Convergent evolution
the process by which unrelated or distantly related species independently evolve similar structures and functions (traits and features) as a result of adapting to similar habitats and ecological roles.
Mutation
A change in the nucleotide sequence of an organism’s DNA that can result in altered proteins or functions. Mutations may occur spontaneously during DNA replication or be induced by mutagens (e.g., radiation, chemicals).
Antigenetic drift
Produces small incremental changes in viral genetic material over longer periods of time.
slowly produces variation in the virus’s surface proteins.
Result is accumulated changes that may eventually prevent immune system from recognising the virus.
Antigenetic shift
1 or more different viral strain or viruses infect same cell and recombine genetic material. Major changes in relatively short amount of time.
Causes rapid + major changes in the virus’s surface proteins.
Result is new virus able to create pandemics as immune system does not recognise the new viral strain.
