BIOLOGY 2D03 Lecture Notes - Retrovirus, Chromosome, Cistron
Document Summary
Virus multiplication (lecture 21: virus consists of a cluster of genes that can replicate insides cells, simplicity in their genetic organization consist of dna or rna, not both, obligate intracellular parasites. Patterns of virion structure: core viral nucleic acid, protein shell capsid either icosahedral or helical, some viruses have lipoprotein envelope surrounding the capsid, capsid built from multiple copies of identical structural units. Icosahedron 20 triangular faces, 12 vertices 2,3 and 5 fold symmetry. Classification: dna or rna, polarity (plus same as mrna, or minus), structure (linear, circular, single- or double- stranded, type of symmetry (helical or icosahedral) of capsid, presence/absence of lipoprotein envelope, presence/absence of specific virion enzymes. Virus infection: one-step growth curve, eclipse very few infectious virus particles can be detected either inside or outside the cell during this time. Intracellular accumulation period newly-synthesized progeny virions can be found inside but not outside the cell: rise period increasing numbers of progeny virions appear in the extracellular fluid.