Source: ©1999 William Reusch, All rights reserved (most recent revision 7/16/2007) – Permission granted

In Translation, the RNA information in nucleotides is used to make a protein. 3 Phases: 1) Initiation 2) Elongation 3) Termination

 mRNA attaches to the ribosome (in cytoplasm)  A ribosome is where protein synthesis occurs  A ribosome is protein and RNA (rRNA)  An initiator or START codon (AUG) turns on protein synthesis.

The large subunit has an A-site (Aminoacyl-tRNA binding site, a P-site (Peptidyl-t-RNA binding site) and an E- site (exit site)

1.Small subunit of the ribosomebinds to the AUG codon forming the initiation complex. 2.A special tRNA called met t RNA enters the small subunit & binds to the start codon. 3.Then the large subunit attaches forming a complete ribosome.

 Transfer RNA (tRNA) picks up amino acids that are circulating within the cytoplasm and shuttles them to the mRNA.  tRNA has an anti-codon that recognizes the codon on the mRNA (i.e. they are complementary).

A bond is formed between the 2 amino acids by ATP

 The amino acids bind to the growing polypeptide chain.  The assembly moves along the mRNA, one position at a time, with tRNA adding amino acid.

 The sequencing of the amino acids is determined by the message carried from the nucleus by the mRNA.  The genetic code is degenerate - there are more than one codon for the 20 different amino acids.

Source: Access the National Health Museum RC/VL/GG/genetic.php

 Translation continues until a STOP codon (UAA, UGA, UAG) is reached.  The protein has been built and translation is turned off.  The result is a polymer or chain of amino acids. A protein is a polypeptide, which is a chain of amino acids

tRNA carrying an amino acid Free tRNA mRNA Ribosome Developing polypeptide

 ml ml  _EK3g6px7Ik

Source: ©1999 William Reusch, All rights reserved (most recent revision 7/16/2007) – Permission granted