Viruses 2 Flashcards
How doe envelop help virus
Envelop helps virus attach to cell and penetrate surface membrane. E.g HIV
How does HIV replicate (complex)
Viruses replicate by
1) viral antigens are detected by receptors embedded in host cell
2) virus moves into host cell and capsid disintegrates, releasing viral genetic material and enzymes in host cell
3) viral RNA is copied by reverse transcriptase to make viral DNA
4) viral DNA moves into host nucleus and is integrated into DNA by viral enzyme integrase
5) viral DNA is copied to make viral mRNA by host cell RNA polymerase
6) viral RNA is translated by host ribosomes to make viral proteins.
7) which may be modified by Golgi
8) viral proteins assembled into new virus
9) new virus buds out of host cell. Wrapped in cell membrane
10) these viruses are free to begin new cycle of infection
What is a pathogen
Pathogen is a microorganism with potential to cause disease e.g bacteria and viruses.
Examples of bacteria and viruses causing disease
Bacteria causes salmonella, cholera
Viruses cause flu, chicken pox
How do viruses replicate (simple)
Viruses replicate by inserting their nucleic acid near host cells genetic material and host cell then creates required proteins for virus replication. Host cell doesn’t realise its foreign
What does a virus do if it has RNA as its genetic material
If a virus has RNA, it will use reverse transcriptase which is used to copy RNA to DNA.
Definition of antigen and what are examples
Antigen definition is a molecule as “non self” (not part of host) and stimulates immune response.
Examples include : glycoproteins in cell membranes, proteins, toxin
What is a virus
Virus is a very small particle which is only capable of replicating once in a living cell. Consists of nucleic acid surrounded by capsid
What cells does HIV infect and why
HIV infects macrophages and T helper cells because they have the CD 4 receptor
