DNA & RNA Notes Unit 3

DNA: deoxyribonucleic acid Genetic material; controls protein synthesis DNA is a very long, thin molecule made up of nucleotides Nucleotides are made up of three components: 1. 5 carbon sugar (deoxyribose in DNA) 2. phosphate group 3. nitrogenous base (ATCG)

Nitrogen Bases 1. Purines: two rings in structure -Adenine & Guanine 2. Pyrimidines: one ring -Thymine & Cytosine Base pairing occurs because adenine only bonds with thymine (A-T, T-A) and guanine only bonds with cytosine (C-G, G-C) The nitrogen bases are held together with hydrogen bonds

DNA structure The sides of DNA are alternating sugars and phosphates Strands condense into two long chains, which twists to form double helix The order of the nucleotides in the center of DNA determines the traits a person has The structure of DNA was determined by Watson & Crick Animation: http://www.johnkyrk.com/DNAanatomy.html

RNA: ribonucleic acid Nucleic acid which carries out protein synthesis (instructions from DNA) Differences from DNA: different sugar (ribose) single strand different base (no thymine, uracil instead)

Types of RNA Messenger RNA: carries specific nucleotide sequence from nucleus to ribosome Transfer RNA: picks up amino acid in cytoplasm and carries it to ribosome Ribosomal RNA: found in ribosome, helps with formation of protein