What are viruses?
Nucleic acid contained within a protective protein coat. Can infect prokaryotes and eukaryotes.
What are the 2 main differences between viruses and bacteria?
1. Antibiotics have no effect 2. Cannot replicate outwith a cellular environment (obligate intracellular parasites; lack critical components for replication)
Label the parts that make up a virus:
A - genome
B - capsid
C - envelope
D - envelope glycoprotein
Describe the components of a virus
- Genome - viral nucleic acid
- Capsid - virus-encoded proteins. Protects genome and facilitates binding/entry of virus into cells
- Nucleocapsid - genome and capsid collectively
- Envelope - lipid bilayer derived from cellular membranes during replication in cell. Not all viruses have these.
- Envelope glycoproteins - Provide viral function, antigens recognised by immune system
What shape are viruses?
Icosahedral or helical
What are the features of an icosahedral virus?
- 20 faces, faces are equilateral triangle
- Some are enveloped eg. herpes virus
- Some are not enveloped e.g. FMD
What are the features of a helical virus?