e here is u r answer>>>>....TRANSLATION Protein synthesis occurs on 'workbenches' called ribosomes in a process called translation. In translation, all 3 primary types of RNA cooperate. mRNA (messenger RNA) carries the genetic information transcribed from DNA to the ribosome; tRNA (transfer RNA) molecules carry specific amino acids to the ribosome to be added to the growing chain; and RRNA (ribosomal RNA), along with proteins, make up ribosomes. RIBOSOME A ribosome has 3: the A site, the P site, and the E site. The A (aminoacyl) site is where amino acids arrive at the ribosome, carried by their respective tRNA molecules. The P (peptidyl) site is where the growing polypeptide is located, attached to the tRNA docked there. The E (exit) site is where a tRNA that has no amino acid attached it is positioned just before it leaves the ribosome. GENETIC CODE A ribosome "reads" an mRNA molecule 3 bases at a time; a set of 3 consecutive mRNA bases that are read as a single unit is called a codon. Because there 4 possibilities (A, C, U, or G) at each of 3 positions, there are a TOTAL of 4^3 = 64 possible codons. The genetic code is the mapping of each of the 64 possible codons to its corresponding amino acid; in a few cases, a codon maps instead to either a START or STOP signal Translation consists of 3 stages: initiation, elongation, and termination. INITIATION There are two separate subunits for a ribosome: a large subunit and a small subunit. The two are separate most of the time, but when mRNA binds to one of them, the other subunit binds to the complex, forming a ribosome and initiating translation. ELONGATION As a given codon sits in the A site, tRNA molecules randomly BUMP into the slot, but they don't dock. Only when a tRNA with a 3-base anticodon that is complementary to the codon in the A site arrives does docking occur. The specific tRNA molecule that docks carries a specific amino acid to the ribosome (this is how codons indirectly code for specific amino acids). The growing polypeptide attached to the tRNA docked in the P site is transferred to the newly arrived amino acid attached to the new tRNA molecule docked in the A site. During a process called translocation, the ribosome moves exactly 3 bases along the mRNA,.This physical shifting CAUSES repositioning of the tRNAs too. The tRNA in the E site leaves the ribosome; the tRNA in the P site is shifted over to the E site; and the tRNA withe growing polypeptide attached shifts from the A site to the P site. All of this positions the next codon to be read into the now-empty A site. The ribosome has been restored to its beginning position, but with the polypeptide now being 1 amino acid longer. These elongation steps are repeated over and over, once per amino acid added to the chain. We can break elongation down into steps. (1) Codon recognition: A tRNA carrying the correct amino acid (determined by complementarity between the tRNA’s anitcodon and the mRNA’s codon) docks in the A site. (2) Peptide bond formation: The existing, growing polypeptide is transferred from the tRNA molecule in the P site to the amino acid on the new tRNA in the A site. (3)Translocation: The ribosome moves 3 bases along the mRNA, moving the uncharged tRNA in the P site into the E (exit) site, the tRNA in the A site (with the polypeptide now attached) into the P site, and positioning a new codon into association with the now-empty A site. (4) Back to step (1) TERMINATION Eventually, a STOP codon is reach, positioned in the A site. A STOP codon does not code for an amino acid, but for a release factor. The release factor binds, dissociating the ribosome into its two subunits and releasing the mRNA and the polypeptide. The polypeptide will then fold into a stable tertiary structure to become a protein