1. What stage of mitosis/meiosis does DNA replicate ?
Agenda for Monday Nov. 1st
DNA replication

2. Central Dogma

3. 3 theories of DNA replication
How are two daughter strands are created?
DNA needs to replicate – creates new cells
These strands should be accurately copied and transmitted from the parental cell to the daughter ones
Meiosis and Mitosis
3 possible models of creating new DNA

4. Conservative Replication
Conservative replication – would leave intact the original DNA molecule and generate a completely new molecule

5. Dispersive Replication
Dispersive Replication would produce two DNA molecules with sections of both old and new DNA interspersed along each strand

6. Semiconservative Replication
Semiconservative replication would produce molecules with both old and new DNA, but each molecule is composed of one old strand and one new one
This is how DNA replicates

8. Semiconservative Replication
Watson and Crick suggested replication method
Semiconservative replication
DNA separates, serve as templates, and produce DNA molecules that have one strand of parental DNA and one new strand of DNA
Occurs during interphase of mitosis and meiosis

9. 3 steps of replication
Unwinding
Base pairing
Joining

10. Unwinding DNA Helicase unwinds/unzips DNA strand
Hydrogen bonds are broken
Proteins adhere to DNA to keep strands separate
RNA Primase adds a short segment to each strand

12. Base Pairing
Steps
DNA Polymerase catalyzes the addition of nucleotides to the new DNA strand
Always starts at 5’ and goes to 3’
Strands are identical (A=T, C=G)
Two strands are created in different ways
One is leading strand
One is the lagging strand

13. Leading Strand Elongated as the DNA unwinds
New nucleotides are added continuously

15. Lagging Strand Elongates away from replication fork
Created in segments
Okazaki Fragment
100 – 200 nucleotides long
Fragments are later connected

16. **New RNA Primer each time

17. Joining Many areas along DNA strand where DNA replication can being
DNA polymerase comes to an RNA primer it removes primer and fills with DNA nucleotide
DNA Ligase links two sections of DNA together

19. Prokaryote vs. Eukaryote
Prokaryotes
1 origin
Eukaryote
Many origins

20. Replicate your DNA Put on a separate sheet of paper.
Discussion Questions 1. Compare the two new strands of DNA. Are they the same or different? Why? 2. How does the structure of a DNA molecule help account for the great variety of life that exists on earth?

22. Questions
Answer questions 1-5 on page 335 in your book