1. DNA Structure & Replication

2. History of DNA Structure
Erwin Chargaff
Rosalind Franklin
James Watson and Francis Crick

3. DNA Timeline

4. DNA
To understand genetics, biologists/chemists had to learn the chemical makeup of “the gene”.
This chemical makeup is called Deoxyribonucleic Acid or DNA

5. Units of Structure
Scientist began studying DNA structure to find out how it carries information, decides traits, and replicates itself.
DNA is a long molecule made up of units called nucleotides.
Each nucleotide is make up of a…
5-carbon sugar
Phosphate group
Nitrogenous base

7. Things to remember…Nucleic Acids
DNA versus RNA

9. DNA versus RNA: structure

10. DNA versus RNA: function

11. DNA - Double Helix A double helix is like a twisted ladder.
Sugar and phosphates make up the two sides of the ladder.
Nitrogenous bases make up the rungs of the ladder.
Hydrogen bonds between the bases hold the two strands together.

12. Nucleic Acids: Nitrogenous Bases

13. Nucleic Acids: Base Pairing (DNA)

14. Nucleic Acids: Base Pairing (RNA)

15. DNA Strands complement each other.
PRACTICE TIME

16. Which direction do I go? Where’s my head? Where’s my butt?

17. DNA Strands are Antiparallel.

18. Counting Carbons

19. Lagging Strand
Leading Strand

21. Loose DNA to Chromosomes
Prokaryotic cells have one large circular piece of DNA in their cytoplasm and several small loops…(why not stored in a nucleus?).
Eukaryotic cells have lots of DNA strands (chromatin) that can form of chromosomes and are stored in their nuclei.

22. Chromatin = Bowl full of Spaghetti

23. How a Chromosome forms. Chromosome formation step by step: 1. 2. 3. 4.5. 6.