1. DNA Replication
SC.912.L Describe the basic process of DNA replication and how it relates to the transmission and conservation of the genetic information

2. DNA REP
Objective: Recall the components and structure of DNA and Describe the process of DNA replication and its role in the transmission and conservation of genetic information.
EQ: How does the process of DNA replication allow for information to be retained and transferred?

3. Structure of DNA Quick review! DNA and Nucleotides…
Which is the polymer and which is the monomer?
Nucleic acids (DNA) = polymer
Nucleotides = monomer
What is the structure of a nucleotide? DNA?
Nucleotide- phosphate, sugar, nitrogen base
DNA- double helix (spiral)
What is the function of N.A.?
Store genetic info

4. Developments in DNA Structure
Erwin Chargaff: determined that different organisms have the same 4 bases but in different ratios
Also noted that the amounts of C and G were relatively the same; A and T were also the same
James Watson, Francis Crick: developed accurate model of DNA’s double helix structure
Used info from x-ray crystallography
Rosalind Franklin, Maurice Wilkins: looked at the structure of DNA using x-ray crystallography

5. Structure of DNA
Deoxyribose Nucleic Acid (DNA) is made up of the monomer: nucleotides
Each nucleotide has 3 parts:
Phosphate group
Deoxyribose (sugar)
Nitrogen-containing base

6. DNA Structure 4 Nucleotides (bases): Adenine (A) Guanine (G)
Cytosine (C)
Thymine (T)
Notice that G and C look similar and pair together!

7. Structure of DNA (Honors)
The only difference between the nucleotides is the nitrogen-containing base
Pyrimidines have single rings (thymine and cytosine)
Purines have double rings (adenine and guanine)

8. Structure of DNA
Single-ring bases pair with double-ring bases to form a double helix (spiral ladder)
Sugar-phosphate backbones form sides of ladder
Nitrogen bases pair to form the rungs of the ladder
Base Pairing Rules:
A pairs with T
C pairs with G

9. Base Pairs (Honors)
hydrogen bond
covalent bond
Nucleotides in a single strand are joined by covalent bonds (sugar and phosphate)
Nucleotides on separate strands (base pairs, two stands) are held together by hydrogen bonds
DO THEY NEED TO KNOW??????

10. Base-Pairs Practice Which base would be paired with… Adenine
pairs with thymine

11. Base-Pairs Practice Which base would be paired with… Cytosine
pairs with guanine

12. Base-Pairs Practice Which base would be paired with… Thymine
pairs with adenine

13. Base-Pairs Practice C – T – A – G – G G – A – T – C – C
Write the sequence of nucleotides that would be paired with the first strand
C – T – A – G – G
G – A – T – C – C

14. DNA Replication
DNA only stores genetic information and acts as a template;
Specialized proteins are used to replicate the DNA
Each single strand of DNA can be used as a template for a new strand
All cells have a complete set of DNA
Different types of cells express the genes differently, but all cells still have ALL DNA

15. Process of Replication
Enzymes (helicase) unzip the double helix at origins of replication
- Occurs in multiple locations on the eukaryotic strand of DNA

16. Process of Replication
2. As lone nucleotides are exposed by the unzipping of the DNA, enzymes (DNA Polymerases) pair free-floating nucleotides in the nucleus with the bases on the original strand
DNA polymerase
new strand
nucleotide

17. Process of Replication
3. The result is two identical strands of DNA - One side of each strand is the original strand (template) - The other side of the strand is the newly-synthesized complementary strand
original strand
new strand
Two molecules of DNA

18. How do you eat DNA-spaghetti? With a replication fork

19. Semiconservative Replication
The process of DNA replication is semiconservative
Each DNA strand is half of the original and half replicated (new)
Conservative replication would have one copy of the DNA with both original strands; the other copy of DNA would have both new strands
Proofreading: enzymes (DNA polymerases) check for errors, replace mismatched nucleotides

20. Think, Pair, Share
Why is it important for the process of DNA replication to be accurate?
To prevent genetic mutations
Where is DNA in the cell? Where does DNA rep take place?
In the Nucleus

21. Left Side Activity! Modeling the structure of DNA… WITH CANDY!!!
Using twizlers, gummy bears, and toothpicks, go through the process of DNA replication.
C- level 2, talk to your table partner
H- ask three before me
A- using provided materials, go through the process of DNA Replication
M- Remain seated in your assigned seat
P- create and replicate your own DNA strand
Success

22. LAB: QKA
During DNA replication two identical DNA molecules are produced from one original molecule. Which statement below explains why the newly formed molecules are identical to the original?
The original DNA molecule breaks down into nucleotides that are reassembled by DNA polymerase into two new molecules.
The nitrogen base adenine can only pair with cytosine and thiamine.
Each strand of the original molecule serves as a template for the two new stands, and new nucleotides are added to the template according to the pairing rule.
The nitrogen base adenine can only pair with guanine and phosphate groups.

23. Exit ticket
Clear your desk of everything except something to write with and your DO NOW.