2. (1) Why Replicate DNA?
• Necessary for cell division because the cell
needs to make a copy of its DNA for the new
cell.
• Errors:
– Can have ZERO impact on the cells.
– Could provide a positive advantage to cell.
– Could kill the cell.
3.
4. (2) Semi-Conservative Replication
• Messelson & Stahl discovered that DNA
Replication is a Semi-Conservative process:
– Semi = ½ or Partial
– Conserve = To Keep or To Save
• You start with 1 whole, old molecule of DNA…
– You end with 2 new molecules of DNA.
– Each new molecule has:
• 1- old strand
• 1- new strand
• (1/2 of the old molecule is conserved in each new one)
5.
6. (3) Replication Basics:
• Overall Goal: Make an Identical copy of
cell’s DNA molecule.
• Basic Steps:
1- Un-twist strands.
2- Separate strands.
3- Make a complimentary copy of each
strand.
• End Result:
2 DNA molecules, each with 1 old strand
and 1 new strand.
