DNA Replication

A. Purpose

  1. To make an exact copy of DNA before cell divison
  2. DNA is double so that each daughter cell will have a complete set of DNA

B. Process

  1. Double helix begins to untwist
  2. An enzyme (helicase) breaks the hydrogen bonds holding the two gases together
  3. This unzips the molecule and exposes the bases on both strands
  4. Each exposed strand serves as a template to create a new, complimentary strand
  5. Another enzyme (DNA polymerase) then moves along each side of the DNA strand and adds complimentary nucleotides (sugar, phosphate, base) to the exposed bases.

a. If the template strand was AATCGT

b. DNA polymerase would add TTAGGA

  1. The two new strands (daughter strands) of DNA begin to twist back into a double helix

C. Results

  1. Two new molecules are created, each containing one template (original) and one complimentary (new) strand.
  2. This is called semi conservative replication: one of the old strands is present in each new molecule of DNA.
  3. The cell can now continue through the rest of the cell divison process