Q.(a) Explain the role of translation components in protein synthesis. OR

(a) Translation depends on mRNA, tRNA and the ribosome working together with enzymes/factors to convert the codon sequence into a polypeptide. (b) The genetic code is triplet, degenerate, unambiguous, non-overlapping, and (nearly) universal, with specific start and stop codons.

(a) Protein synthesis (translation) occurs on ribosomes and requires several essential components. Messenger RNA (mRNA) carries the genetic information transcribed from DNA in the form of a sequence of codons (triplets of nucleotides), each specifying a particular amino acid. Transfer RNA (tRNA) molecules act as adaptors: each tRNA has a specific anticodon loop that base-pairs with a complementary codon on the mRNA, and carries the corresponding amino acid attached at its 3' acceptor end; the correct amino acid is loaded onto each tRNA by a specific aminoacyl-tRNA synthetase enzyme, using ATP. The ribosome, made of ribosomal RNA (rRNA) and proteins in a large and a small subunit, provides the physical platform for translation; it has three functional sites - the A (aminoacyl) site where a new charged tRNA enters, the P (peptidyl) site where the growing polypeptide chain is held, and the E (exit) site from which the uncharged tRNA leaves. The process also needs initiation factors (to assemble the ribosome at the start codon), elongation factors (to help move charged tRNAs into the A site and translocate the ribosome), release factors (to terminate translation at a stop codon), and GTP as an energy source for several of these steps.

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