1. DNA Structure and Function

2. What is DNA? DeoxyriboNucleic Acid DNA is a Nucleic Acid The main job of DNA is to make PROTEINS. Proteins build your body, help you grow, and repair damage.

3. What is the function of DNA? It is your genetic material or “program.” Passed from cell to cell. DNA can give clues to ancient mysteries!

4. Where do you find DNA? DNA is found in the nucleus of the cell. Our genes are on our chromosomes. Chromosomes are made up of a chemical called DNA.

5. “Building Blocks” of DNA Each nucleotide consists of  Deoxyribose (5-carbon sugar)  Phosphate group  A nitrogen-containing base (A, G, T, C)

6. Nucleotide Structure CH2 O C C CC Sugar Sugar(deoxyribose) N Nitrogenous base (A, G, C, or T) (A, G, C, or T) O=P-O OPhosphate Group Group

7. Nitrogen Bases Adenine (A) Guanine (G) Thymine (T) Cytosine (C) A or G T or C

8. DNA Structure Watson-Crick Model DNA is also called: The Double Helix Strands are held together by hydrogen bonds between bases Bases: A matches with T and C matches with G The sides of the ladder are a sugar-phosphate backbone, while the “rungs” of the ladder are the bases.

9. DNA is a double strand

10. The four bases of DNA are: Adenine (A) Guanine (G) Thymine (T) Cytosine (C) Make a copy of the following DNA Sequence: DNA(Original): A T C G C G A A T C C A G Copy: T A G C G C T T A G G T C Base-Pairing Rule

11. DNA replication Before mitosis and meiosis, all of the DNA in the cell must be copied or replicated How does this happen?

12. new old DNA Replication Half of the replicated DNA strand is “old” and the other half is “new”

13. Basepairing During Replication Each old strand serves as a template for the new complementary strand

14. DNA Replication: Fast & Accurate! It takes E. coli <1 hour to copy 5 million base pairs in its single chromosome & divide to form 2 identical daughter cells Human cell copies its 6 billion bases & divide into daughter cells in only few hours Remarkably accurate  only ~1 error per 100 million bases  ~30 errors per cell cycle

15. DNA Repair Mistakes can occur during replication Proofreading enzymes correct any mistakes that occur during replication. DNA studies have helped us solve major problems in history and in health. Ex. The Czar’s family in Russia, crime scene investigation, and paternity tests.