7/23/2009
DNA Replication
DNA is the genetic material of living
organisms and is located in the
chromosomes of each cell.
If every organism must produce copies
of itself in order to pass on genetic
information to its young before it dies,
how is its DNA copied?
DNA functions in the same way for all
organisms. It unites us all, and at the same time,
i makes
it
k each
h off us unique.
i
DNA replication is the process
of a DNA molecule making a
copy of itself.
DNA replication ensures that each
daughter cell has an exact copy of
the genetic material from the
parent cell.
• DNA replication occurs before
mitosis begins and before the
first division of meiosis.
DNA replication results
in one DNA molecule
becoming two daughter
molecules —each an
exact copy of the
original molecule.
Steps in DNA replication
1.
2.
3.
4.
5.
Replication begins with the partial unwinding
of the double helix.
The base pairs separate.
A special
p
molecule moves along
g each original
g
strand of DNA and “reads” the bases.
A new strand is assembled along each original
strand. (New pieces come from the cytoplasm.)
The strands re-twist and two daughter
molecules are produced.
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7/23/2009
Both strands of the
original DNA molecule
have remained intact.
Each daughter molecule
is made of one original
strand and one new
strand.
Animation of the process of
DNA replication
p
http://www.lpscience.fatcow.com/jwanamaker/animations/DNA%20
Replication%20-%20long%20.html
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