1. January 6, 2017
Objective:
To be able to explain and model how DNA replicates
To describe how the structure of DNA relates to how it replicates
Journal: Draw a nucleotide and label it’s three parts.

2. DNA Replication

3. Replication Process by which DNA makes an exact copy of itself
Results in 2 identical DNA molecules

4. Discussion Question
Turn to someone next to you and come up with an answer to the following question.
Why would an organism want two identical molecules of DNA?

5. Why replication?? Copies the genetic code
Allow new cells to have exactly the same genetic info as old cells
This is how traits are passed on
Can be used to make new cells

6. Sites of Replication
Specific nucleotide sequences called origins of replication are required to be present for DNA replication to begin
There can be many origins of replication along same DNA strand
Speeds up the process

7. How does replication work?
Step 1:An enzyme called DNA helicase unwinds the DNA by breaking the hydrogen bonds between the nitrogen bases
Forms a replication fork

8. How Replication Works
Step 2: Single Stranded Binding Proteins keep the DNA strands apart

9. How Replication Works
Step 3: An enzyme called DNA polymerase then matches up complementary DNA nucleotides with the nucleotides on the old DNA strand continuously in a 5’ to 3’ direction.
This is called the leading strand

10. How Replication Works
Step 4: The other DNA strand, the lagging strand, still has nucleotides added to it by DNA polymerase, but they have to add in short strands called Okazaki fragments since the lagging strand goes in the 3’ to 5’ direction

11. How Replication Works
Step 5: DNA ligase connects the Okazaki fragments together

12. How Replication Works
Step 6: DNA polymerase then bonds the sugar and the phosphate from each nucleotide together forming a complete strand of DNA

13. How Replication Works
Results: Each new DNA strand contains ½ of the original strand and ½ new nucleotides
This is known as semiconservative because each strand has half the old strand.

14. Crash Course Video