Chapter 25

1. Chapter 25 DNA replication

2. DNA Review • DNA is a nucleic acid • The components are • Deoxyribose • Phosphate • Nitrogen Base • The nitrogen bases are • Guanine, Cytosine, Adenine, and Thymine • The structure is... • Double helix

3. DNA Replication • DNA needs to be replicated so cells may divide • 3 steps in replication • Unwinding  The two strands that were held together by hydrogen bonds separate and the hydrogen bonds break. The Enzyme DNA Helicase “unzips” the DNA • Complementary Base Pairing  nucleotides fit into place • Joining  the complementary nucleotides join together to make new strands. They are joined with the enzyme DNA Polymerase

4. This is the Unwinding stage. DNA Helicase This is where the Nitrogen Base Pairs pair up with the old DNA DNA Polymerase combines the nucleotides and changes it into a new strand

7. This DNA replication is called Semiconservative because each new double helix has one old strand and one new strand • DNA replication occurs in the nucleus and it needs to happen before cell division • The old strand is called the parent strand • The new strand is called the daughter strand

8. Recombinant DNA