DNA DNA is a type of organic macromolecule

DNA § DNA is a type of organic macromolecule called Deoxyribonucleic Acid § DNA is made up of repeating monomers called Nucleotides § DNA has a distinct shape called a Double Helix § The discovery of the shape of DNA is credited to James Watson and Francis Crick § Rosalind Franklin used x-ray diffraction to discover the shape and shared her work with Watson and Crick

DNA § Each nucleotide is made of 3 parts: § 5 -carbon sugar (deoxyribose) § Phosphate group § Nitrogenous base § The “backbone” of DNA is made of the sugar and phosphate group to give the molecule support on the outside § DNA strands will run in a 3’ to 5’ or 5’ to 3’ direction § The oxygen in the sugar points to the 5’ end like an arrow

DNA § § The deoxyribose sugar, phosphate, and base are held by covalent bonds Nitrogenous bases are held together by hydrogen bonds § Nitrogenous bases in DNA: § Thymine (T) § Cytosine (C) Pyrimidines– single rings § Adenine (A) § Guanine (G) Purines– double rings

DNA § Chargaff’s Rule: equal number of adenine to thymine & guanine to cytosine § Bases are “complimentary”, meaning they always match with another §A–T §C–G § This means if 1 DNA strand is AGGCTGAGC, the complementary strand is T CCGACTCG § Match the nucleotides of the given DNA strand to create the complementary strand: GCTTAGTCGTA CGAATCAGCAT