1. DNA Replication

2. What is Replication? DNA makes an exact copy of itself.
Process is semi- conservative (each strand produced will contain one copy of the original strand and one copy of the new).
It takes about eight hours for one of your cells to completely copy its DNA.

3. Important Concepts Strands run anti-parallel (in opposite directions)
New nucleotides are added from the 5’ (5 prime) to 3’ (3 prime) end.
Leading strand is copied continuously
Lagging strand is copied in fragments

4. The DNA molecule unzips in both directions.
Steps of Replication
1. Helicase unwinds the double helix.
Breaks hydrogen bonds, stands separate.
The DNA is unwound in opposite directions.
The DNA molecule unzips in both directions.

5. Steps of Replication (cont.)
2. DNA polymerase (enzyme) bonds free-floating nucleotides (in the nucleus) to the exposed strands.
DNA polymerase
new strand
nucleotide

6. Steps of Replication (cont.)
3. DNA polymerase proofreads the new DNA strand. If the wrong nucleotide was added, will be replaced with the correct nucleotide.
Errors in replication are about 1 per 1 billion nucleotides

7. Steps of Replication (cont.)
Two new molecules of DNA are formed, each with an original (parent) strand and a newly formed (daughter) strand.

8. Videos Bozeman: https://www.youtube.com/watch?v=FBmO_rmXxIw
Crash course (DNA structure and replication)
DNA Replication animation:
DNA Replication animation (2): lgenetics/dna-rna2.swf
DNA Replication animation (3):