1. DNA Structure

2. DNA stands for... Deoxyribonucleic Acid

3. Chromosomes and DNA
•DNA, genes, and chromosomes compose the molecular basis for heredity.
•A chromosome is a structure in the nucleus of a cell consisting of one long thread of DNA that is tightly coiled

4. Genes and DNA
• A gene is a specific location on a chromosome, consisting of a segment of DNA
• Each chromosome consists of hundreds of genes determining the many proteins for an organism.

5. Discovering the structure of DNA
• Discovered in 1953 by James Watson & Francis Crick
- double helix; twisted ladder; spiral staircase

6. DNA Structure cont. Rosalind Franklin -
XRay Defraction Image of DNA proved that it was a double helix/twisted ladder shape

7. Discovery of DNA Timeline

8. DNA: codes for your genes (traits) •made of repeating subunits called nucleotides

9. What is a nucleotide? Three components: 1. PHOSPHATE
2. DEOXYRIBOSE (sugar)
3. BASE (A,T,G,C)

10. Base-Pair Rule Adenine <==> Thymine Guanine <==> Cytosine
The sides/backbone of the DNA
ladder are phosphate
& sugar held together
by hydrogen bonds.

11. Base Pair Rule
One side: A T A T C A T G C G G G
Other side: