1. DNA Replication

2. Step1 of DNA Replication: Helicase unwinds and “unzips” the molecule.
5′ end
3′ end
Helicase
3′ end
5′ end

3. Step1 of DNA Replication: Helicase unwinds and “unzips” the molecule.
5′ end
3′ end
Helicase
3′ end
5′ end

4. Step2 of DNA Replication: DNA polymerase adds bases to the template strand starting at the 3′ end and moving toward the 5′ end.
3′ end
5′ end
DNA
POLYMERASE
3′ end
5′ end

5. 5' 3'
Helicase 3' 5'

6. 5' 3'
RNA primer 3' 5' 3'
“Leading Strand” 3' 5'

7. 5' 3'
RNA primer 3' 5'
“Leading Strand” 3' 5'

8. 5' 3' 3' 5'
“Leading Strand” 5' 3' 5'

9. “Lagging Strand” “Leading Strand”5'
“Lagging Strand” 3'
Okazaki Fragment #1
Okazaki Fragment #2
Okazaki Fragment #3
“Leading Strand” 3' 5'

10. “Lagging Strand” DNA Ligase5'
“Lagging Strand” 3'
Okazaki Fragment #1
Okazaki Fragment #2
Okazaki Fragment #3
DNA
Ligase

11. Overall direction of DNA replication3′
Overall direction of DNA replication
Replication Fork-
Site where DNA is being duplicated. 5′ 4 3 3′ 2
Helicase-
Unwinds and unzips the DNA. 1
DNA polymerase-
Adds new nucleotides to the parental strand of DNA. 5′

13. Replication Bubble

14. There are multiple replication bubbles along one strand of DNA

15. The arrows in this picture are pointing to replication bubbles
The arrows in this picture are pointing to replication bubbles. This is a real photograph taken with an electron microscope.