BIOC 4403 Lecture Notes - Lecture 5: Virus Classification, Reoviridae, Poliovirus

• School: Dalhousie University
• Department: Biochem & Molecular Biology
• Course: BIOC 4403
• Professor: Archibald John

Document Summary

Viruses: entities whose genomes are elements of nucleic acids that replicate inside living cells using the cellular synthetic machinery, and cause the synthesis of specialized elements (virions) that can transfer the genome to other cells. Virus classification: by the nature of the genome (baltimore classification), shape and capsid structure, presence of envelope, type of cellular organisms they parasitize. Dsdna-rt (rna intermediate) (hepatitis b) (+) ssrna (poliovirus) (-) ssrna (influenza, ebola) ssrna-rt (dna intermediate) (retroviruses like hiv) Virus abundance: very abundant, 10 million per ml of seawater. Viral genomes: do not have typical features can be linear, circular, alternating. Gene density is high, often compositionally biased (high at or gc) they are fast evolving and divergent gene sequences extremely diverse in coding capacity. Virus-specific genes: orfans without detectable homologs larger genomes have more orfans, virus specific genes conserved in a group of viruses no cellular homologs.