How is mRNA translated to an amino acid code?

Key Terms:

• tRNA
• translation factor
• anticodon loop
• ribosome
• rRNA
• polyribosome
• start codon
• missense mutation 
• nonsense mutation

Act 1: Initiation

• initiation factors assemble small unit ribsome, mRNA, initiator tRNA, and large unit ribosome to start synthesis of protein.
• small ribsome attaches to mRNA (5' AUG 3') 
• threee binding sites: P(peptide), A(amino acid), & E(exit) site
• P contains tRNA with peptide attached to it

Act 2: Elongation

• A contains tRNA with another amino acid which is added to polypeptide
• tRNA that no longer has amino acid is translocated to E site
• Amino acid continually added to growing polypeptide chain to make a protein
• The amino acids are attached by peptide bonds (covalent)

Act 3: Termination

• stop codons "UAA", "UAG", or "UGA" stop synthesis of protein
• everything dissociates