1. Nucleotides & Nucleic Acids Roles: Energy currency (ATP, GTP) Chemical links in response of cells to hormones (cAMP) Involved in cofactors (NAD, FAD, CoA) Metabolic intermediates (acetyl CoA) Constituents of nucleic acids, DNA and RNA Central Dogma of Biology Storage and transmission of genetic info Contains genes rRNA - structural components of ribosomes mRNA - carries genetic info from gene to ribosome to make protein tRNA - adaptor that translates info in mRNA into amino acid sequence

2. Nucleotides & Nucleic Acids Nucleotides: 1. Nitrogenous base 2. Pentose sugar 3. Phosphate Nucleosides: 1. Nitrogenous base 2. Pentose sugar Nitrogenous bases are either pyrimidines or purines

3. Nucleotides & Nucleic Acids Nitrogenous bases are either pyrimidines or purines

4. Nucleotides & Nucleic Acids Ribose sugars can be either 2’-deoxy (DNA) or have a 2’-OH (RNA)

5. Nucleotides & Nucleic Acids

6. Hydrolysis of RNA

7. Nucleotides & Nucleic Acids Properties of RNA and DNA Forces involved in structure 1.

8. Nucleotides & Nucleic Acids Properties of RNA and DNA Forces involved in structure 1. Hydrophobic Bases hydrophobic at neutral pH, hydrophobic stacking interactions

9. Nucleotides & Nucleic Acids Properties of RNA and DNA Nitrogenous rings are mostly planar Resonance in cyclic rings allow nucleotide bases to absorb UV light

10. Nucleotides & Nucleic Acids Properties of RNA and DNA Forces involved in structure 2. Hydrogen bonding patterns in RNA and DNA Involve ring N, carbonyls, amino groups Permits complementary association of 2 strands of nucleic acid (structure of DNA by Watson & Crick) Uridine (RNA)

11. Nucleotides & Nucleic Acids Discovery of DNA structure and its role in housing genetic information Miescher 1868 Isolate phosphorus-containing substance which he termed “nuclein” Acidic (DNA) & basic portions (protein) Hypothesize that nuclein associated with genetic inheritance Avery-MacLeod-McCarty 1944 Direct evidence that DNA carries genetic info

12. Nucleotides & Nucleic Acids Discovery of DNA structure and its role in housing genetic information Avery-MacLeod-McCarty 1944 Direct evidence that DNA carries genetic info

13. Nucleotides & Nucleic Acids Discovery of DNA structure and its role in housing genetic information Avery-MacLeod-McCarty 1944 Direct evidence that DNA carries genetic info Griffith Avery-MacLeod-McCarty ?? Results Treat DNA with protease - transform Treat DNA with deoxyribonucleases- destroy transforming activity

14. Nucleotides & Nucleic Acids Hershey-Chase 1952 More evidence that DNA carries genetic info DNA radiolabeledProtein radiolabeled

15. Nucleotides & Nucleic Acids Chargaff’s rules 1940s 1. Base composition of DNA varies from one species to another 2. DNA from different tissues of same species have same base composition 3. Base composition of DNA in given species does not change with age, nutritional state, environment 4. In all cellular DNAs, regardless of species, the number of adenosine residues is equal to the number of thymidine residues (A=T), and the number of guanosines = cytidines (G=C) A + G (purines) = C + T (pyrimidines)

16. Nucleotides & Nucleic Acids Watson & Crick 1953 (Franklin & Wilkins too) Franklin & Wilkins Used x-ray crystallography to analyze fibers of DNA X - indicates helical structure Heavy bands - indicates recurring bases

17. Nucleotides & Nucleic Acids Watson & Crick 1953 (Franklin & Wilkins too) Watson & Crick Used x-ray crystallography data Used Chargaff’s rules 3D structure of DNA, strands antiparallel

18. Nucleotides & Nucleic Acids DNA structure Complementarity (replicate by separating strands and synthesizing complementary strand for each) Strands not identical in base sequence or composition DNA replication

19. Nucleotides & Nucleic Acids DNA structure - different 3D forms