BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Each three-letter sequence of mRNA nucleotides corresponds to a specific amino acid, or to a stop codon. UGA, UAA, and UAG are stop codons. AUG is the codon for methionine, and is also the start codon.

Detailed explanation-2: -Each group of three bases in mRNA constitutes a codon, and each codon specifies a particular amino acid (hence, it is a triplet code). The mRNA sequence is thus used as a template to assemble-in order-the chain of amino acids that form a protein.

Detailed explanation-3: -It was also known that there are only four nucleotides in mRNA: adenine (A), uracil (U), guanine (G), and cytosine (C). Thus, 20 amino acids are coded by only four unique bases in mRNA, but just how is this coding achieved?

Detailed explanation-4: -Codons are made up of any triplet combination of the four nitrogenous bases adenine (A), guanine (G), cytosine (C), or uracil (U). Of the 64 possible codon sequences, 61 specify the 20 amino acids that make up proteins and three are stop signals.

Detailed explanation-5: -The three-letter nature of codons means that the four nucleotides found in mRNA-A, U, G, and C-can produce a total of 64 different combinations. Of these 64 codons, 61 represent amino acids, and the remaining three represent stop signals, which trigger the end of protein synthesis.