Chapter Outlines
Chapter 2 Eukaryotic Molecular Biology and Host Cell Constraints
| [View Chapter Outlines list]
|
Eukaryotic Molecular Biology and Host Cell Constraints
- Virus particles
- Enveloped viruses
- Naked viruses
2.1 How Many Genes Are Required to Build a Simple Virus Particle?
- Viruses have small genomes compared to other microbes and organisms
- Viruses are dependent upon the host cell for replication
2.2 Molecular Biology Review
Central Dogma
- Replication, transcription, and translation are localized processes in the cell.
Eukaryotic DNA replication
- DNA polymerase
- Synthesis is 5’->3’ direction
- DNA polymerases
Eukaryotic RNA replication
- RNA polymerases
- Synthesis is 5’->3’direction
- transcription factors
- enhancers
- Eukaryotic mRNAs
- Capped
- Polyadenylated
- Movement to cytoplasm
Review of Open Reading Frames (ORFs)
Cap-dependent Initiation of Translation
- Initiation of eukaryotic translation uses many eIFs
- 3 steps
- initiation
- elongation
- termination
Ribosomal scanning model
Translation and open reading frames
- frameshifting
- translational readthrough
Why do all viruses use the host’s protein synthesis machinary?
- Viral genomes are too small to carry all of the genes essential to translate their viral mRNAs
- some viruses bypass cap-dependent translation host requirement
- Called cap-independent translation
Leaky Scanning
Post-translational Processing of Proteins
- Examples:
- glycosylation
- phosphorylation
- proteolytic cleavage
2.3 Molecular Constraints of the Host Cell
- Host cells do not possess RNA-dependent RNA polymerases
- Eukaryotic host protein synthesis machinery only is only equipped to translation monocistronic mRNAs
- Viral mRNAs compete with host mRNAs for protein synthesis machinery
- DNA viruses and cell cycle issues
|
