DNA Replication

2.5.1. State that DNA replication is semi-conservative.
DNA is semi-conservative.

2.5.2. Explain DNA replication in terms of unwinding of the double helix and separation of the strands by helicase, followed by formation of the new complementary strands by DNA polymerase.
When replication takes place, the enzyme helicase first unwinds the double helix . Next the two DNA strands are split apart at hundreds, sometimes thousands, of points along the strand. Each splitting point is an area where replication is occuring, called a replication bubble. In each replication bubble, new DNA is made by attaching free nucleotides to the original strand (called the template) by base-pairing rules with the help of the enzyme DNA polymerase. The process results in two identical DNA strands produced from one.
2.5.3. Explain the significance of complementary base pairing in the conservation of the base sequence of DNA.
Because the nitrogenous bases that compose DNA can only pair with complementary bases, any two linked strands of DNA are necessarily complementary to one another. The fact that only complementary base pairs can join together means that in replication the newly formed strands must be complementary to the old strands, thus conserving the same base sequence as previously existed.