1. What is DNA? Instructions for making proteins
‘Blueprint’ for who we are
Where is it found?
Found in the nucleus
What does ‘DNA’ stand for?
Deoxyribonucleic Acid

2. The Structure of DNA
Double helix
Structure of DNA: Twisted Ladder

3. Who Discovered DNA’s Structure?
SCANDAL! Read all about it!
Rosalind Franklin, James Watson, Francis Crick, & Maurice Wilkins discovered the shape (double helix) of DNA is 1953.

4. DNA is a polymer of Nucleotides. What are the 3 parts of a nucleotide?
Review
DNA is a polymer of Nucleotides.
What are the 3 parts of a nucleotide?

5. DNA Subunit 3 components a sugar a phosphate group a nitrogen base
Nucleotides
DNA Subunit
3 components
a sugar
a phosphate group
a nitrogen base

7. Nitrogen Bases 4 Types: Adenine Thymine Guanine Cytosine REMEMBER:
At The Golf Course

8. Complementary Base Pairs
Nitrogen bases always pair with the same partner
Hydrogen bonds hold the bases together.
A--T (At--The)
G--C (Golf--Course)

9. What would the complementary strand be? A-T-C-C-G-T-T-T-A-C-A-G-G-A
THINK!
What would the complementary strand be? A-T-C-C-G-T-T-T-A-C-A-G-G-A
T-A-G-G-C-A-A-A-T-G-T-C-C-T

10. Nucleotides join to form a long chain (polymer) Sides of the ladder:
How DNA Strands Form
Nucleotides join to form a long chain (polymer)
Sides of the ladder:
Sugar + Phosphate
Rungs of ladder:
Nitrogen bases bond together (with H-bond)

11. How is DNA Organized?
Histone proteins act like spools that wind up DNA to keep it organized.

12. During Interphase…
How does DNA exist?
Unwound! (Chromatin)

13. Why Chromatin? What happens during Interphase?
DNA Replicates!
DNA is uncoiled so that enzymes can unzip it.
When it is unzipped, DNA can be duplicated.

14. DNA Replication
Process where DNA is copied
Occurs before mitosis and meiosis (during interphase!)

15. DNA Replication
During replication, each strand of the double helix serves as a template for the formation of the new strand of nucleotides.

16. Important enzymes
DNA helicase- breaks the weak hydrogen bonds between nitrogen bases to unzip DNA .
DNA polymerase- links nucleotides together to form DNA strands.
Ligase- “Glues” Okazaki fragments back together to form a complete strand.

17. How DNA Duplication Occurs
Step 1: Enzymes (Helicase) unzip the DNA strand T A G C
ENZYME

18. Step 2: Free nucleotides bind to the complementary bases
Step 2: Free nucleotides bind to the complementary bases. (DNA Polymerase) T A G C

19. Result: 2 Complete Strands!
Old T A G C
New
New
Old

20. DNA Replication (5’-3’) It happens all over the strand!

21. Semiconservative Replication: one of the original strands is present in each new strand of DNA.

22. Makin’ Copies for Mitosis: Growth, Repair, and Reproduction!

23. The Central Dogma of Genetics
DNA RNA Proteins