Block 9 Week 3 Flashcards
Virus Diagram
- All RNA viruses are single stranded with the exception of ROTA VIRUS.
- All DNA viruses are double stranded with the exception of PARO VIRUS ( single stranded DNA virus).
RNA vs DNA
+sense vs - sense
Naked vs Envelope
Virus Nucleic acid: + Sense vs - Sense
Sense strands only applies to single stranded RNA. It can either be positive sense or negative sense.
- For most viruses once they get into a host cell their number one goal is to go through a host ribosome. This is because once it has gone through the host ribosome it will be able to make viral proteins. Viral proteins help the virus to further replicate itself.
+sense RNA strand has a sequence of nucleic acids so that when it goes through a ribosome it will make a functional protein.
-sense RNA strand is a complement of the +sense RNA.
-The nucleic acids code for stop codon.
- viral RNA polymerase uses the -sense strand to create a +sense RNA which can go through the ribosome to make a protein.
- All -sense RNA viruses have a envelope.
Virus: Nucleic Acids: Reverse Transriptase
- Some Viruses have an enzyme (reverse transcriptase) which can convert RNA back to DNA.
- Most common is HIV virus. It gets into host, converts it RNA to DNA, inserts itself into the host genome so that the virus can become latent for many years.
- Another example HBV (hepatitis B virus)
Virus: Nucleic acids
- nucleic acids can be linear or circular or linear segments
- Mutations are common in viruses becuase they have no proof reading capabilities. So its often the viruses reproduced have errors
- Because of this its difficult to make medication against viruses because they are constantly mutating
Viral proteins
- Protein capsid: surrounds viral genome
- Replicative proteins: polymerase and trasnscriptase
- Protein antigen: bind receptors and antibodies
Viral envelope
- lipid layer around capsid.
- Not present in all viruses. But is always present in RNA single stranded viruses
Envelope has 2 functions:
- Protective membrane
- fusion onto host cell