1. –DNA functions as the inherited directions for a cell or organism. –How are these directions carried out? Flow of Genetic Information Gene DNA RNA Protein Amino acid Nucleic acids

2. Gene DNA RNA Protein Amino acid Nucleic acids –An organism’s genotype is its genetic makeup, the sequence of nucleotide bases in DNA. –The phenotype is the organism’s physical traits, which arise from the actions of a wide variety of proteins. Flow of Genetic Information

3. Phosphate group Nitrogenous base  A, G, C, or U  Uracil  U  Sugar  ribose  Nitrogenous base (A,G,C, or T) Phosphate group Thymine (T) Sugar (deoxyribose) Phosphate Base Sugar ●Nucleic acids are polymers of nucleotides –DNA, deoxyribonucleic acid –RNA, ribonucleic acid Nucleic Acids

4. Review nucleotide structure: Nucleic Acids

5. ●Each DNA nucleotide has one of the following bases: Adenine (A) Guanine (G) Cytosine (C) Thymine (T) Adenine  A  Guanine  G  Thymine  T  Cytosine  C  ● Each RNA nucleotide has one of the following bases: Adenine (A) Guanine (G) Cytosine (C) Uracil (U)

6. DNA Structure *Early 1950’s Rosalind Franklin *1953 Watson and Crick

7. Sugar-phosphate backbone Nucleotide Base pair Hydrogen bond Bases  a  DNA strand  polynucleotide   b  Double helix  two polynucleotide strands  ●Nucleic Acid Structure DNA Structure

8. Sugar-phosphate backbone Phosphate group Nitrogenous base DNA nucleotide Nucleotide Thymine (T) Sugar Polynucleotide DNA double helix Sugar (deoxyribose) Phosphate group Nitrogenous base (can be A, G, C, or T) DNA Structure

10. Complementarity ”It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism … “ Mode of DNA Replication Semiconservative DNA Replication

11. *Overview: DNA replication *Complementarity determines which nucleotide will be added *Chain elongation in a 5’- to-3’ direction DNA Replication

12. Initiation *Primase *Strands must separate Helicases SSBPs DNA gyrase *Two are antiparallel Continuous DNA synthesis = leading Discontinuous DNA synthesis = lagging DNA Replication

13. A large team of enzymes carry out DNA replication: Helicases SSBPs DNA gyrase Elongation: Association of polymerase Sliding clamp Primase DNA synthesis (DNA pol) Primer removal and replacement (DNA pol) Ligase closes the gaps DNA Replication