Question by correctomundo: translation.?
what is translation?
and where does it occur and what does it produce?
Answer by ATP-Man
Translation: t-RNA : a specialized form of RNA used to carry a specific amino acid to the ribosome and place it in the proper position. t-RNA contains 80 nucleotides in the form of a clover leaf. The t-RNA must attach the correct amino acid to itself. The process is as follows:
1. The specific amino acid reacts with a specific enzyme and ATP to release 2 P and combine the AMP and the amino acid.
2. The t-RNA will replace the AMP and bond with the amino acid.
Ribosomes: Before translation ribosomes consist of 2 separate sub-units. As translation proceeds the ribosome parts come together to allow protein synthesis to begin.
There are 3 steps to protein synthesis:
1. Initiation: m-RNA binds to the small subunit of the ribosome. There is 1 binding site for the m-RNA, and 2 binding sites for the t-RNA. The P site holds for the t-RNA carrying the growing polypeptide and the A site for the t-RNA carrying the next amino acid. AUG ( start codon ) is in place and the appropriate t-RNA delivers the amino acid Methionine. The large sub unit then joins and creates a functional ribosome.
2. Elongation: The chain moves from the 5′ – 3′ direction caused by the use of GTP and several protein-enzyme complexes. As the polypeptide chain is produced the t-RNA move from site A to site P, and then are released into the cytoplasm. The polypeptide chain continues to grow, and is held to the ribosome by the t-RNA at the P site.
3. Termination: The termination codons: UAA, UAG, and UGA stop the process by adding water to the end of the chain instead of an amino acid. In order for the protein to become functional, it must be folded into its appropriate shape,and/ or have some amino acids removed, and/or have some of the polypeptides modified by adding sugars or phosphate groups to them.
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