Protein Synthesis How are they made??

Review DNA contains the ‘instructions for the cell’ or instructions for making proteins Proteins are long chains of amino acids bound together (also called polypeptides)

Protein synthesis Has 2 different steps = making proteins Transcription Translation

Step 1 = Transcription Where does transcription start and end? Overview: section of DNA is copied into a piece of mRNA RNA polymerase separates one section (a specific gene) of DNA in the nucleus and uses one strand as a template to make the mRNA strand  Where does transcription start and end? Specific nucleotides tell the process when to start and stop The start sequence is called a promoter Initiates transcription by allowing RNA polymerase to bind to one side of the DNA The stop sequence is called the terminator Signals end of gene and stops the process

What does the transcribed DNA tell us? Just like DNA, mRNA nucleotides are ‘read’ 3 at a time Called a codon Each codon specifies for a particular amino acid The order of mRNA codons determines the order of amino acids that will be linked together during our next step Practice Original strand TAC GGA TTC CGT TTT AAG ACT mRNA complementary strand

Step 2 = Translation Overview = mRNA is read at the ribosome by tRNA which brings amino acids to build our polypeptide chains (proteins) tRNA Amino Acids themselves cannot recognize codons on the mRNA, so the tRNA helps them ‘translate’ Each tRNA carries only one type of amino acid The three nitrogen bases on the tRNA are called anticodon Complementary to the mRNA codon Original strand AUG UUU GUG CCU GGU UGA tRNA complementary strand