Genetic Code

Chapter 10-3

4 Letters

DNA contains instructions; RNA is the understood language

RNA has only 4 nitrogen bases (nucleotides): U, A, C, G

The nucleotides are read in groups of three

Codons

Codon: a group of 3 nucleotides in mRNA that specifies an amino acid

Example:AAACACGGUAAA – CAC - GGUlysine – histidine - glycine

Start signal: AUG Stop signal: UAA, UAG, UGA

Translation

Nucleotides in mRNA are decoded into a sequence of amino acids in a polypeptide Floating in cytoplasm are amino acids

and tRNA mRNA (codon) has a complimentary

tRNA (anticodon) bound with a specific amino acid