1. DNA REPLICATION NOTES

2. 1. DNA HELICASE
Enzyme that unwinds DNA helix by breaking hydrogen bonds that hold nitrogen bases together
As the two strands separate, they form a Y shape, called the replication fork

3. 2. TOPOISOMERASE/DNA GYRASE
Relives tension has helicase unwinds DNA, by breaking the bonds between the sugar and phosphates

4. 3. Single stranded binding proteins (ssbp)
Prevent nitrogen bases from reattaching to one another

5. Shows DNA polymerase where to start binding new base pairs
4. Rna primase
Binds complimentary base pairs in short fragments in 3’  5’ direction of replication fork
Shows DNA polymerase where to start binding new base pairs

6. 5. DNA polymerase III
Adds new base pairs in the 3’ 5’ direction by starting where at the end of RNA primers

7. 6. Nucleoside triphosphates
Source of energy for DNA polymerase III to synthesize new DNA

8. Built in one continuous strand
7. Leading strand
New DNA strand that is built in the same direction as the replication fork
Built in one continuous strand

9. Built in the opposite direction as the replication fork
8. Lagging Strand
Built in the opposite direction as the replication fork
Built in short fragments called “Okazaki Fragments”

10. Replaces RNA bases from the RNA primers with DNA bases
9. DNA polymerase i
Replaces RNA bases from the RNA primers with DNA bases

11. Join together Okazaki fragments and sugar and phosphate molecules.
10. Dna ligase
Join together Okazaki fragments and sugar and phosphate molecules.
Often called the “glue”

12. Proofread new DNA strands and fix mismatched base pairs
11. exonucleases
Proofread new DNA strands and fix mismatched base pairs