1. DNA Structure and Function

2. The Role of DNA Molecule of Heredity –Stores information for various genetic traits –Controls development and growth of each cell as well as the entire organism –Copies itself : before a cell divides, genetic information must be copied –Transmits information from one generation to the next http://www.youtube.com/ watch?v=l0TC9Lt7IGU& safe=active

3. What is the structure of DNA and how was it discovered? The Chemical Structure of DNA I: http://www.youtube.com/watch?v= nExcd_wTcHg&safe=activehttp://www.youtube.com/watch?v= nExcd_wTcHg&safe=active

4. Discovery of DNA Structure –Watson-Crick: worked together on DNA structure and came up with “double helix” model –Won Nobel Prize in 1962 –Helped by X-ray crystalography images by Rosalind Franklin The Chemical Structure of DNA II: http://www.youtube.com/watch?v=oZiAwqo77GM&s afe=activehttp://www.youtube.com/watch?v=oZiAwqo77GM&s afe=active

5. Chargaff’s Ratios: –Helped scientist understand how the bases paired up http://www.hhmi.org/biointeractive/media/DNAi_chargaff_ratio-lg.mov

6. The Chemical Structure of DNA DNA: (Deoxyribose Nucleic Acid) Large Polymer Molecule Two long chains of nucleotide subunits Nucleotides from each chain pair up and bond together with hydrogen bonds Hydrogen bonds (weak) Strand 1Strand 2

7. Nucleotide Structure –3 components of nucleotide: 5 carbon deoxyribose sugar Phosphate group Nitrogenous Bases –Adenine, thymine, cytosine, guanine 4 bases possible (A, T, C, G) http://www.hhmi.org/biointeractive/media/DNAi_ building_blocks-lg.mov

8. Nitrogenous Base Pairs –Adenine - Thymine –Cytosine - Guanine

9. Nucleotides join together into two long chains Phosphate of one nucleotide is joined to sugar of next nucleotide by a covalent bond The two chains are joined together by hydrogen bonds (weak bonds) between the nitrogenous bases. Base pairs always A-T, C-G http://www.youtube.co m/watch?v=qy8dk5iS1f0 &safe=activehttp://www.youtube.co m/watch?v=qy8dk5iS1f0 &safe=active

10. Double Helix Structure Base pairs are rungs on a ladder Sides of ladder are phosphate and sugar Whole ladder is twisted into a “double helix” structure Video: Chemical Structure of DNA III http://www.youtube.com/watch?v=54n8DLr eEe4&safe=activehttp://www.youtube.com/watch?v=54n8DLr eEe4&safe=active http://www.hhmi.org/biointeractive/media/DNAi_paired_ strands-lg.movhttp://www.hhmi.org/biointeractive/media/DNAi_paired_ strands-lg.mov

11. Order of A, T, C, G nitrogenous bases eventually codes for different proteins. The order of nucleotides is unique for different organisms The more closely related two organisms are the more similar the DNA sequences –Way to determine evolutionary relationships Nucleotide Base Sequence

12. Build a DNA Molecule http://learn.genetics.utah.edu/content/begi n/dna/builddna/http://learn.genetics.utah.edu/content/begi n/dna/builddna/

13. DNA Replication DNA duplicates itself prior to cell division Each strand serves as a pattern or “template” to make a new DNA molecule

15. Enzymes: –Break open (unzip) weak H-bonds between bases pairs –Bind free nucleotides to complimentary bases of unzipped single strand (DNA polymerase)

16. Produces 2 identical DNA double helix strands (called complimentary strands) Each new strand made of one of the original strands plus one new synthesized strand. http://www.youtube.com/watch?v=z685FFq mrpo&safe=activehttp://www.youtube.com/watch?v=z685FFq mrpo&safe=active http://www.youtube.com/watch?v=zdDkiRw 1PdU&safe=activehttp://www.youtube.com/watch?v=zdDkiRw 1PdU&safe=active

17. Focus Question Why is accuracy so important in replication of DNA?