1. DNA Replication What is replication? When does replication occur? Why do we need replication?

2. What is Replication? Replication is the process of making a copy of the DNA molecule. *Each newly synthesized DNA has one parent (old) strand and a new daughter strand of DNA.

3. Why Must Replication Occur? Replication must occur so that each new cell After (mitosis) gets a complete, set of DNA. Interphase ??

4. When Does Replication Happen? Replication occurs during “S” phase of interphase of the Cell Cycle.

5. Replication: Step #1 a.An enzyme called DNA “helicase” unzips the parent strand by breaking the hydrogen bonds. b.This causes the complementary base pairs to separate. *Making replication bubbles and forming a replication fork. replication bubble

6. Replication: Step #2 a. An enzyme called DNA “polymerase” gathers free nucleotides floating in the nucleoplasm. b. DNA polymerase pairs the free nucleotides w/its complementary base partner, following the base pair rule. *Pairing of the bases occurs in opposite directions simultaneously. *In humans, DNA polymerase adds 50 nucleotides per second.

7. Replication: Step #3 a. An enzyme called DNA “LIGASE” binds the newly attached free nucleotides. b. DNA ligase acts as glue on the new strand of DNA being formed

8. Replication The end result is two identical strands of DNA that are now present in the nucleus. *Each newly synthesized DNA has one parent (old) strand and a new daughter strand of DNA. *This is called a semi-conservative process.