MCB 2000 Chapter Notes - Chapter 6: Reverse Transcriptase, Exocytosis, Provirus
Document Summary
Protein coat - capsid: capsid is composed of protein subunits called capsomeres. Enveloped viruses: some viruses have the capsid covered with an envelope (lipids, proteins, and carbohydrates) Morphology of viruses: based on capsid structure there are three different morphological types: Naked helical viruses: long rods, the capsid is cylindrical with helical structure (tobacco mosaic virus) Enveloped helical viruses: helical nucleocapsid placed within an envelope (influenza) Polyhedral viruses: the capsid is a regular polyhedron with 20 triangular faces (poliovirus, nucleic acid packed in the center. The viral envelope: roughly spherical, sometimes the envelope is covered with spikes (carbohydrates, function of capsid/envelope: Attachment of viruses to the host cells. Introduction of nucleic acid into host cell. At the core of a virus: either dna or rna. Double/single stranded rna: single stranded rna. Negative sense (need to be converted into a proper form: genom is small. Human genom: 30,000 genes: besides nucleic acids core may contain enzymes required for replication.
