Chemistry Reference
In-Depth Information
A researcher places tubes of DNA in a PCR machine.
(Martin
Shields/Photo Researchers, Inc.)
The earliest PCR used DNA polymerase from ordinary cells,
but the heating caused the enzyme to stop functioning, so a
new batch of enzymes had to be added during each cycle. To-
day, PCR uses a DNA polymerase derived from heat-loving bac-
teria that live in extremely hot environments. These DNA poly-
merases are able to maintain their function even at the highest
temperature settings in PCR, avoiding the need to replenish the
enzymes at each step. Modern PCR machines are automated,
requiring the user merely to provide the initial solutions, punch
a button, and relax until the operation is complete.
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