1. Nucleotides and nucleic acids Nucleotides: small molecules –Components of nucleic acids –Energy storage (eg. ATP) –Signal transduction/info transfer (eg. cAMP) –Components of coenzymes (eg. NADH) Nucleic acids: polymers –Major role: information transfer DNA: genetic information RNA: ‘translate’ genetic info into protein 1° structure: messenger RNA –Component of proteins eg. ribosomes Other RNA-containing proteins (mRNA splicing) –Enzyme “ribozymes”

2. Nucleic acids are polymers of nucleotides “Nucleoside” = base + sugar 1.Phosphate 2.Nitrogenous base 3.Sugar (pentose)

3. Nitrogenous bases

4. Sugar (ribose/deoxyribose) H 2’ position: Hydroxyl in ribose Hydrogen in deoxy-

5. Phosphate group

6. Adenosine 5’-triphosphate

7. Polymerization via phosphodiester linkage

8. Structure of DNA “Double helix” Discovered by Watson & Crick, but also Franklin & Wilkins (~1940s/50s) Two strands running anti- parallel Contains large major groove and smaller minor groove –H-bond donors/acceptors, protein binding

9. Antiparallel 5’ 3’ 5’ 3’

10. DNA strands held together by weak interactions “Watson-Crick” base pairing A (purine) with T (pyrimidine) G (purine) with C (pyrimidine) Complementarity: genetic information Non-specific interactions: van der Waals forces stabilize helix formation via ‘base stacking’

12. Watson-Crick base pairing A-T: two H-bonds G-C: three H-bonds –More G/C content = stronger bond between strands (melting temperature) Not all potential H-bonds are used: areas for proteins, other molecules to bind (major/minor groove)

13. Base pairing allows for information storage

14. RNA Translates DNA information into protein sequence –Messenger (mRNA) ‘Charges’ amino acids for incorporation into polymerizing protein –Transfer (tRNA) Part of the structure of ribosomes –Ribosomal (rRNA) Other functions –Small nuclear (snRNA) –Genome (RNA viruses) –Catalytic (ribozymes)

15. RNA is typically single stranded still has complex 3D structure

16. Three dimensional structure of RNA