1. Set up Cornell Notes on pg. 5
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.

2. EQ: This is a template (guide to follow)

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 ¼ of pg. 4: REVIEW
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 does the word replication mean?
A copy or reproduction.

8. 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!

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

10. 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).

11. Make a Key: original strand and new strand in 2 different colors
Original/Parent strand
New “Complementary” Daughter strand
nucleotides
unzips
Helicase
a fragment of DNA

12. 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”?

13. The DNA Polymerases, add nucleotides only to the 3’ (3 Prime) end of the strand
new strand
nucleotide 3’ 5’
complementary 5’ 3’

14. 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
Why do we call the new “daughter” strand complementary and not identical to the “parent” or original strand?

15. 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

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

17. 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!

18. Homework
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
if you need to, change the key to meet your color needs

19. Marshmallow DNA Replication Activity

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

21. DNA Replication Video