Download Human Virology Viruses are the most common cause of acute

Human Virology
Viruses are the most common cause of acute infections in humans
What are viruses?
http://www.youtube.com/watch?v=7O9JPyY44VA
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Obligate intracellular parasites
o
They cannot perform metabolism on their own.
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Viruses are simple Darwinian machines. They survive because they make huge amount
of mutants. Selection removes the non-fittest.
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Many viral diseases can be viewed as a failure of the virus to adapt to its host.
The Origins of Virology
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A hieroglyphic found in 3700 BC, Memphis ancient Egypt. Typical clinical signs of
paralytic poliomyelitis
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Ramesses V’s preserved mummy shows that he died of smallpox at about the age of 35
in 1143 BC.
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The Chinese suffered from small pox in 1000 BC, China. They realized they can do
something about it. Variolation.
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1519 A.D Smallpox was transferred from Europe to the Americas
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The Year 1796. Edward Jenner vaccinated a boy against smallpox boy, with material
from a cowpox lesion.
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The Year 1892. Dmitri Iwanowski, showed that extracts from diseased tobacco plants
can transmit disease to other plants by infectious agent smaller than a bacteria.
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The 1918 Spanish Flu pandemic. 40-50 million deaths worldwide.
What Virus Are Not?
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They are NOT cellular organism. They are a bunch of chemicals, proteins, etc.
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Outside a cell – are not considered to be alive.
All cellular life has the following characteristics in common:
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DNA
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RNA
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Making PROTEINS
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SUPPLY OF ENERGY
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REPRODUCE
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CELL MEMBRANE
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REGULATION
BASIC CHEMICALS
Viruses versus cellular organisms
Viruses
Cells
Metabolic capabilities
No. totally depend on host
ATP and most other
compounds
Extensive synthesis of ATP,
vitamins lipids nucleic acid
etc.
Independent translation
No, cannot make t/rRNA
yes
Hereditary material
DNA or RNA; can be single or
double stranded
DNA; always double stranded.
Expressed into t/r/mRNA
Reproduction
Assembly of preformed
components
Cell division
Size
Nano Meter Range
Micro Meter Range
http://www.cellsalive.com/howbig.htm