1. Number pgs. in new notebook 1-100
Set up Cornell Notes on pg. 3
Topic: 8.3 DNA Replication
Essential Question:
Explain how DNA serves as its own “template” during replication.
8.3 DNA Replication
2.1 Atoms, Ions, and Molecules
Explain how DNA serves as its own “template” during replication.
Key Concept: DNA replication copies the genetic information of a cell.
Number pgs. in new notebook
1-100

2. P. 2

3. T A C G T A T G A A A C T G G T T T A G A A T T
On the top 1/2 of pg. 2: REVIEW pg
1. What stage of the cell cycle does
DNA replication occur?
2. Why is it important that the DNA is replicated before mitosis occurs?
3. Following the base-pairing rules, please complete the two DNA sequences below :
T A C G T A T G A A A C
T G G T T T A G A A T T

4. T A C G T A T G A A A C A T G C A T A C T T T G
What stage of the cell cycle does DNA replication occur?
S stage or Synthesis
Why is it important that the DNA is replicated before mitosis?
Each cell must have a full set of DNA
T A C G T A T G A A A C
A T G C A T A C T T T G
T G G T T T A G A A T T
A C C A A A T C T T A A

5. Do you know that your cells are dying right now?
Connect
Do you know that your cells are dying right now?
You may live to 100, but most of your cells will have been replaced thousands of times before then
Every time that cells divide to produce new cells, DNA must first be copied in a remarkable process of unzipping and zipping by enzymes and other proteins.
Mitosis

6. KEY CONCEPT DNA replication copies the genetic information of a cell.

7. What is a template?
guide to follow

8. What does the word replication mean?
A copy or reproduction.

9. DNA Replication copies the genetic information so that we have two identical strands of DNA.
complementary
original strand
new strand
Two molecules of DNA
What does identical mean????
Exactly the same!

10. The rules of base pairing direct replication.
Remember: What are our base pairing rules?
A=T
C=G

11. Get 2 colors: Make a KEY for your two colors
Original “Parent” Strand
New Complementary “Daughter” Strand
DNA polymerase
new strand
nucleotide
unzips

12. Enzymes and other proteins do the actual work of replication.
1. The enzyme Helicase “unzips” the double helix (Hydrogen bonds now broken between the bases)
“Free-floating” nucleotides form hydrogen bonds with the original or “parent” strand ( acts as our template).

13. Ready for a dirty sounding, but not so dirty pickup line
Ready for a dirty sounding, but not so dirty pickup line? Its OK its biology!!!

14. nucleotides 1.
unzips
Helicase
a fragment of DNA

15. 1. unzips How does DNA unzip?
Helicase breaks the hydrogen bonds between the base pairs
nucleotides
unzips 1.
Helicase
a fragment of DNA

16. 2. DNA polymerase (pol-uh-muh-rays) enzymes bond the nucleotides together to “complementary” bases to form the double helix.
Complementary =
Go together
Ex: A-T
C-G
What do you think they mean by “complementary”?

17. The DNA Polymerases, add nucleotides in a 5’ (five prime) to 3’ (three prime) direction
new strand
nucleotide 2. 3’ 5’
complementary 5’ 3’

18. 3. Two identical molecules of DNA are formed, each with an original strand and a “complementary” newly formed strand.
complementary
original strand
new strand
Two molecules of DNA 3.
Why do we call the new “daughter” strand complementary and not identical to the “parent” or original strand?

19. Because they are not identical!
Ex: Where the parent strand has an “A” the daughter strand will have…
“T”
complementary
original strand
new strand
Two molecules of DNA

20. DNA is called semiconservative because one original strand is conserved, and one complementary new strand is made.
complementary
original strand
new strand
Two molecules of DNA
What does it mean if you “Conserve” something?
You save it!

21. Original “parent” strand
Complementary
original strand
new strand
new “daughter” strand
Original “parent” strand
Conserving the original strand = semiconservative

22. Why is it important for the cell to correct any errors that occur during replication?
If errors are not corrected, one of the new cells that form during mitosis would have DNA with incorrect genetic information
complementary
original strand
new strand
Two molecules of DNA
You save it!

23. Replication is fast and accurate.
DNA replication starts at many points in eukaryotic chromosomes.
There are many origins of replication in eukaryotic chromosomes.
Origin of replication
DNA polymerases can find and correct errors.

24. A closer look
Replication proceeds in both directions, creating what are called replication “bubbles”
Shortens the time needed for the process
Thousand of bubbles can be present at once

25. Leading strand Lagging strand
DNA’s sugar-phosphate backbones run in opposite directions
Each strand has a 3’ (three-prime) end and a 5’ end
At one end of each DNA strand, the sugar’s 3’ carbon atom is attached to an –OH group
At the other end, the sugar’s 5’ carbon has a phosphate group
Leading strand
*Building goes in the 5’ to 3’ direction
Lagging strand

26. Leading strand Lagging strand Draw on the bottom ½ of pg. 2
*Building goes in the 5’ to 3’ direction
Lagging strand

27. Lagging strand has a much more difficult time
Lagging strand has a much more difficult time. It must replicate “backwards” and in fragments called Okazaki fragments (O.F.)

28. DNA replication video (1m40-2m50)

29. Classwork- DNA replication!
On the back of your DNA Replication picture page please follow your base-pairing rules and complete the unzipped strand of DNA.
Follow the color-coding guide

30. Marshmallow DNA Replication Activity