BIOSC 0100 Lecture Notes - Lecture 1: Aids, Hiv, 1918 Flu Pandemic

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6 Feb 2017
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Chapter 32
Virus:
-An obligate, intracellular parasite
-Eters a host ell ad use the host’s iostheti ahier to reprodue ad sthesize iral
proteins
-Each type of virus infects a specific unicellular species or cell type in a multicellular
-In the human body, virtually every system, tissue, and cell can be infected by at least one kind
of virus
-Viruses have caused the most devastating epidemics in recent human history
-Spanish flu (1918-1919) killed up to 50 million people
-Human immunodeficiency virus (HIV) causes acquired immune deficiency syndrome
(AIDS) and has caused almost 30 million people
-Very small, ranging in size from 20 to 300 nm in diameter
-Virus comes from the Latin word meaning poison
Structure:
-Virus particle = virion
-Consists of genetic material (DNA or RNA) the viral genome (all the genes for an organism)
-A protein coat called a capsid that surrounds and protects the genome
-Envelope a membrane around the capsid
-There is a wife diversity of viral genome types
-May consist of DNA or RNA
-May be linear or circular
-May consist of a single molecule or have several different segments
-May be single stranded or double stranded
Infection:
-Replication growth:
-Produces the next generation of virions
-Often kills the host cell
-Enter a state of dormancy that suspends virion production
-Allows the virus to coexist with the host for a period of time, replicates the viral DNA
each time the cell divides
Lysogency:
-Inserts its viral geoe ito the host’s DNA – replication is of both genomes
-Cells divide and the virus is transmitter into daughter cells
-Virus gain entry to cells by binding to a specific molecule on the cell wall or plasma membrane
-The viral genome can them be uncoated at the cell surface
-HIV recognizes the CD4 receptor
-Viruses can also be bought into the cells by endocytosis
-Viruses aot ake their o proteis ad ust eploit the host ell’s iostheti ahier to
produce viral proteins
-In addition to transcription and translation, virsues must also copy their genetic material to make a new
generation of virions
-They depend 0n the host cells for nucleotides
-DNA viruses usually depend on the host cell DNA polymerase to replicate their genomes
-Most RNA viruses use a viral RNA polymerase called RNA replicase, which synthesizes RNA from
an RNA template
Retroviruses:
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