In General, Describe the Process Whereby MRNA That Has Exited

Question

Examlex · Accepted Answer

The Answer is mRNA is read in triplets, from the initiator codon (AUG), which codes for the amino acid methionine, to a termination codon. Translation is started by initiation factors that bind to the cap group on the mRNA, while other factors form a complex with small ribosomal subunits and a charged tRNA (containing an amino acid). The tRNA with an anticodon will bind to the codon on the mRNA by the Law of Complementary Base Pairs. The large ribosomal subunit then binds, causing initiation factors to dissociate, thereby aligning the first tRNA with the P site of the ribosome. A second charged tRNA with the appropriate anticodon will attach itself to the A site on the ribosome. An enzyme within the ribosome then catalyzes the formation of a peptide bond between amino acids, and the first tRNA will be released from the amino acid. The ribosome will then move three bases down to the next codon. As the first tRNA leaves the P site, the second tRNA will move from the A to the P site. Then, a new charged tRNA will bind to the A site; the tRNA with the anticodon that matches the mRNA. This process will continue until the termination codon is reached. The leader sequence will determine whether the protein will remain in the cytosol or attach to the endoplasmic reticulum. Post -translational modification is required in order to make the protein functional, and this process can occur anywhere from the rough endoplasmic reticulum to the Golgi apparatus. The leader sequence must first be cleaved as well as any other excess amino acids that are present on the protein. Thereafter, other molecules can be added to proteins, like carbohydrates (glycoprotein), or lipids (lipoproteins), in order to make the protein functional.

In General, Describe the Process Whereby MRNA That Has Exited

Definitions: