CELLS: Viruses Flashcards
What are viruses in their simplest form?
Nucleic acids surrounded by protein.
They are acellular and not alive.
How big is a HIV virus?
About 0.1μm across.
How big are viruses in comparison to bacteria?
They are smaller than bacteria.
What do viruses not have, that bacteria do?
- Plasma membranes
- Cytoplasms
- Ribosomes
What genetic material do viruses contain?
DNA or RNA.
What nucleic acids does HIV contain?
RNA
How do viruses replicate?
Only within the cells of another organism.
What are host cells?
The cells which viruses invade and reproduce in.
In a virus, what encloses the nucleic acid?
The capsid- a protein coat.
In a virus, what is the capsid?
The protien coat that encloses the nucleic acid.
What do some viruses, like HIV also have?
An extra layer - a lipid envelope.
What is the lipid envelope?
An extra outer layer that surrounds some virsues, like HIV.
What is the role of attachment proteins?
They are essential in allowing the virus to identify and attach to a host cell.
Where are attachment proteins found?
On the lipid envelope.
If this is not present, then on the capsid.
Label the structure of HIV:
How do viruses replicate inside of a cell?
- Attachment proteins bind to complementary receptor proteins on the surface of host cells.
- Virus injects their DNA or RNA into the host cell.
- Hijacked cell uses its own organelles to replicate the viral particles - genome replication and gene expression.
- New viral particles are assembled from genome copies and viral proteins.
- Completed viral particles exit the cell and can infect other cells.
This is known as lytic infection.
Why can some viruses only infect one type of cell?
- Different viruses have different attachment proteins and therefore requier different receptor proteins on host cells.
- Therefore, some virsues can only infect one type of cell.
Why don’t viruses undergo cell division?
Because they are not alive and are acellular - they are not cells.
