Set up Cornell Notes on pg. 3 Topic: 8.3 DNA Replication Essential Question :

1. 8.3 DNA Replication 2.1 Atoms, Ions, and Molecules • Set up Cornell Notes on pg. 3 • Topic: 8.3 DNA Replication • Essential Question: • Explain how DNA serves as its own “template” during replication. • 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. On the top 1/2 of pg. 2:REVIEW pg. 134-5 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. 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. 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. new strand original strand Two molecules of DNA • DNA Replication copies the genetic information so that we have two identical strands of DNA. complementary What does identical mean???? Exactly the same!

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

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

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? Its OK its biology!!!

14. unzips nucleotides 1. Helicase a fragment of DNA

15. unzips • How does DNA unzip? • Helicase breaks the hydrogen bonds between the base pairs nucleotides 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. nucleotide new strand DNA polymerase • The DNA Polymerases, add nucleotides in a 5’ (five prime) to 3’ (three prime) direction 2. 3’ 5’ complementary 5’ 3’

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

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

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

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

22. original strand new strand Two molecules of DNA • 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 You save it!

23. There are many origins of replication in eukaryotic chromosomes. Replication is fast and accurate. • DNA replication starts at many points 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. 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. Draw on the bottom ½ of pg. 2 Leading strand *Building goes in the 5’ to 3’ direction Lagging strand

27. 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