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Virus
Core concepts
A virus is a non-cellular particle which consists of a core of nucleic acid (DNA or RNA) surrounded by a protein coat (capsid). It is an infectious agent that is only capable of metabolism and reproduction within a living cell.
In order to reproduce, viruses must infect a host cell in one of two ways: through a lytic or a lysogenic cycle.
Key words
Virus capsidbacteriophage/phage lytic cyclelysogenic cycle virulent phagetemperate phage prophage/provirusRetrovirus reverse
transcriptaseViroid prionInterferon vaccine
Dmitri Iwanowskie and the TMV
Ukrainian biologist and founder of virology
Adolf Mayer suggested an infectious agent affecting tobaccos
Using the steps in the Koch’s postulate he was able to extract the tobacco mosaic virus
TMV
Virus structure
Virus
“Organisms at the edge of life”Have genes, evolve, reproduce(self-assembly)No cellular structure (unit of life)Do not have own metabolism (requires host)Need host cell to reproduceGoverned by natural selectionGives proof to chemosynthetic theory
Taxonomy
Order (-virales)Family (-viridae)
Subfamily (-virinae)Genus (-virus)
Species (-virus)
Classification
Genetic MaterialShapeSizePresence of envelopeSpecificityDisease type
Genetic material
DNA virusRNA virus
Also called retrovirus
If a virus has a single stranded genetic material it is more prone to mutation
Viral infection
Very SpecificBinds to surface receptors
Lytic Cycle
Lysogenic Cycle
Lytic and Lysogenic cycle
The retrovirus and HIV
Whys is a retrovirus very dangerous? Genetic stability- exists as a provirus High expression Flexible genome
Possible Origin of Virus
pieces of cellular DNA that became part of an infectious particle
although small and relatively simple, are not likely to have been the first living things on earth since they’re completely dependent on living cells
may have evolved from genetic material of living cells, and continue to evolve along with their host cells