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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:
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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: AAACACGGU AAA – CAC - GGU lysine – 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