Sequence of amino acids in a polypeptide chain of protein molecule coresponds to the sequence of nucleotides on mRNA for that protein. If reading frame of mRNA for a human protein is 993 nucleotide including a stop codon at the end, how many amino acids would be incorporated in the polypeptide chain?

330

Explanation:

A codon is the sequence of three nucleotides on mRNA that refers for particular amino acid during translation (protein synthesis) process. The four nucleotides arrange themselves in various combinations to produce different codons. The tRNA with corresponding anticodon attach the particular amino acid to polypeptide chain during translation.

Remember there is always a stop (UAA) and start codon (AUG) for the synthesis of polypeptide and stop codon does not contribute for any amino acid. It just terminate the polypeptide chain synthesis. We know that a codon is made up of three nucleotide so our calculation will be.

                                     993-stop codon =990

                                     990/3=330

So that's why 330 amino acid will be incorporated in the polypeptide chain.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products