DNA Replication

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DNA Replication
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• 1 Nucleotide
• 1 Phosphate
• 1 Deoxyribose sugar
• 1 Nitrogen Base

• Deoxyribose is a 5 carbon sugar. Chemists
  number each carbon according to its position in
  the sugar.

• The numbering system is used when describing

DNA Replication
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• The arrangement of the nucleotide is ALWAYS the
  same
• The Nitrogen base binds at the 1 position, and
• The Phosphate group binds at the 5 position

• The 3 position is also important. The
  phosphate group of the next nucleotide binds at
  the 3 carbon.

So, each strand of the DNA molecule runs in a 5
to 3 direction (from one nucleotide to the next)
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Lets Simplify

• ACGTTCAGGCAAGT
• TGCAAGTCCGTTCA

5
3
Strand 1
Hydrogen bonds
DNA
Strand 2
5
3
Sugar Phosphate backbone

• Remember that the strands are complimentary.
• The top strand runs 5-3 (L-R) and the bottom
  strand runs 5-3 (R-L)

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And nowDNA replication
First the Hydrogen bonds between the nitrogen
bases are broken
?
The original strands serve as templates during
replication
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A
C
5
3
5
3
G
Then new strands form using the template and the
pool of nitrogen bases floating in the nucleus
T
G
A
A
G
T
C
T
T
G
C
C
Replication occurs in a 5-3 direction on a
3-5 template
T
T
C
C
3
5
3
5
T
G
A
A
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Final Product

• When replication is complete we end up with two
  identical DNA molecules
• Each molecule contains 1 original
  strand and 1 new strand

Original

New
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