1. Reminder-four classes of large biomolecules Carbohydrates/polysaccharides Lipids Proteins/polypeptides Nucleic acids/polynucleotides

2. Two Types Nucleic Acid DNA and RNA Synthesis of mRNA mRNA DNA NUCLEUS CYTOPLASM mRNA Ribosome Amino acids Polypeptide Movement of mRNA into cytoplasm Synthesis of protein 123 Function: Information Storage And Control

3. Components of nucleic acids Nucleic acids are polymers Nucleotides are the monomers Each nucleotide consists of a base, a sugar and a phosphate But the base plus the sugar without the phosphate is called a nucleoside Bases are purines (Pu) or pyrimidines (Pyr) Sugars are either ribose or 2-deoxyribose

4. Phosphodiester Bond Links nucleotides together Sugar and phosphate involved This example is a 3’-5’ bond Gives two distinct ends

5. Sugar-phosphate backbone 5 end 5C5C 3C3C 5C5C 3C3C 3 end (a) Polynucleotide, or nucleic acid (b) Nucleotide Phosphate group Sugar (pentose) Nucleoside Nitrogenous base 5C5C 3C3C 1C1C Nitrogenous bases Cytosine (C)Thymine (T, in DNA) Uracil (U, in RNA) Adenine (A) Guanine (G) Sugars Deoxyribose (in DNA) Ribose (in RNA) (c) Nucleoside components Pyrimidines Purines

6. RNA Structure Individual chains in cells Aka “single-stranded”: ssRNA Chains generally from 50- 5000 nucleotides Distributed throughout the cell

7. RNA molecules fold up on themselves Secondary structure refers to folding pattern Confers unique shape Primary structure is the 5’ to 3’ sequence of bases 5’ 3’

8. DNA structure-different from RNA Two molecules interact to form double strand

9. Important features of the double helix Antiparallel strands Bases on the inside Chain held together by hydrogen bonds Watson-Crick base pairs AT and GC are the Watson-Crick base pairs Complementary

10. DNA Structure Almost always double helix Aka “double- stranded”: dsDNA Not as flexible as RNA Chains can be very long 120,000,000 nucleotides Distributed throughout the cell Sequestered

11. Individual nucleotides Mononucleotides Have different functions Energy carriers Help with enzyme reactions as cofactors Signalling