1. DNA Deoxyribonucleic Acid

2. The DNA Connection What have you learned about inheritance, DNA, and cell division up to this point? How do genes determine the traits of an organism?

3. Where is DNA? Inside the nucleus of a cell. Chromosomes are made of DNA. Each chromosome contains thousands of genes.

5. The Importance of DNA DNA tells the body how to make proteins. Proteins help to determine all of your physical traits. Directions for making proteins are found on genes.

7. What are Chromosomes? Chromosomes are dark, rod-shaped bodies found in the cell nucleus. Chromosomes are composed mostly of proteins and DNA.

8. History of DNA

9. Rosalind Franklin Used X-ray diffraction (the way molecules bend X-rays) to determine the structure of molecules. One of the photographs suggested that DNA was a helical (spiral) structure.

10. James Watson & Francis Crick Created the double helix model. Recognized the ability of DNA to form exact copies of itself.

12. Structure of DNA (Twisted Ladder – Double Helix) Nitrogen Bases Sugars Phosphates

13. The Sides of the “Ladder” Sugars and phosphates form the “backbone” of the DNA molecule. The name of the sugar is DEOXYRIBOSE.

14. The Rungs of the “Ladder” The DNA molecule is made up of four different nitrogen bases. * Adenine – Thymine * Cytosine – Guanine The bases attach to the sugar part of the DNA backbone (sides). The order of the bases form a genetic code that specifies what type of protein will be produced.

16. DNA Replication

17. How Does it Work? DNA molecule “unzips” down the middle into two pieces. It breaks apart where the bases are joined. Extra bases are made in the cytoplasm. These bases pair up with the “free” bases. Two new complete DNA molecules form which are identical to the original DNA.