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A&P Cell Physiology

Terms in this set (43)

Translation is the process of making protein and occurs in the cytoplasm with the aid of ribosomes. Protein synthesis can occur either in cytosol, using free-floating ribosomes, or on rough endoplasmic reticulum (rRER), using fixed ribosomes. In the cytosol many free-floating ribosomes attach to a single strand of mRNA at the same time and begin "reading" the genetic sequence on the mRNA. The ribosomes that attach to the strand of mRNA form molecular "docking stations" that enable another molecule, transfer RNA (tRNA), to also bond to the mRNA strand. Each tRNA carries a specific amino acid and has a specific anticodon that correlates with the particular amino acid it carries. The "reading" process involves the bonding of a specific anticodon on the (tRNA to a complimentary codon on the mRNA. At the docking site tRNA molecules bond to the mRNA molecule, bringing the amino acids they carry into close approximation of one another. This allows the amino acids to bond directly to one another. Once the amino acid it carries is bonded to the adjacent amino acid, the tRNA molecule leaves the ribosome to pick up another amino acid. Over time a chain of amino acids, called a polypeptide chain, forms on the ribosome. When the chain has reached its required length, it disconnects from the ribosomal "docking station" and floats out into the cytosol (or if translation occurred on RER, the peptide is taken into the tubular cisternae of the RER for modification). Polypeptides are linked together to form proteins.