Protein synthesis

• In humans, there are 20 different amino acids
• Amino acid order

  Determines the shape of the protein and its function
• Protein sequence

  Determined by the sequence of bases in the gene for that protein
• Protein synthesis


  1. Cell reads DNA sequence as triplets of bases

  2. Each triplet encodes for a specific amino acid

  3. First stage takes place in the nucleus

  4. Second stage takes place in the cytoplasm
• Transcription


  1. Base sequence of the gene is copied into a complementary template molecule

  2. Template is called messenger RNA (mRNA)

  3. mRNA is a single stranded molecule
• Translation


  1. mRNA molecule attaches to a ribosome

  2. Amino acids are brought to the ribosome on carrier molecules called transfer RNA (tRNA)

  3. Ribosome reads the triplets of bases on the mRNA and uses this to join together the correct amino acids in the correct order

  4. Protein chain folds into its unique shape