The process of translation.

Translation begins when mRNA binds to rRNA, there are 3 process to translation.

1. Initiation:  This is when the small subunit of a ribosome charged with tRNA and the amino acid methionine encounters an mRNA, then attaches and starts to search for a start signal.
   When the start signal AUG is found, the codon for the amino acid methionine the large subunit joins the small subunit to form a complete ribosome and protein synthesis initiates.
   
2. Elongation: A new tRNA and amino acid enters the ribosome at the next codon. Down stream of the AUG codon, If AUG anticodon matches the mRNA codon its base pairs and ribosomes can link the two amino acids together.  (If a tRNA with the wrong anticodon and therefore the wrong amino acid enters the ribosome, it cant base pair with the mRNA and is rejected.) The ribosome then moves one codon forward and a new tRNA and amino acid can enter the ribosome and procedure is repeated.
   
3. Termination: When the Ribosome reaches of 3 stop codons for example UGA. There are no corresponding tRNAs to that sequence instead termination proteins bind to the ribosomes and stimulates the realise of the polypeptide chain, the ribosome dissociates from the mRNA. When the ribosome is released from the mRNA, its large and small subunit disassociates. The small subunit can now be loaded with a new tRNA and methionine and then translation starts again. Some cells need large quantities of a particular protein, To meet this requirement they make many of the corresponding gene and have working on each mRNA.