question_answer

Assertion : The concept of one gene-one enzyme was changed to one gene-one polypeptide. Reason : Each enzyme may consist of two or more different polypeptide.

A) If both the assertion and the reason are true and the reason is a correct explanation of the assertion

B) If both the assertion and reason are true but the reason is not a correct explanation of the assertion 

C) If the assertion is true but the reason is false

D) If both the assertion and reason are false

E) If the assertion is false but reason is true

Correct Answer: A

Solution :

In 1948, Beadle and Tatum proposed that a gene controls the synthesis of one enzyme. But, many enzymes, as well the haemoglobin were shown to consist of two or more different polypeptide chains and each polypeptide was found to be the product of a separate gene. Tryptophan synthetase of E. coil, for example, contains and -polypeptide, the product of the trp A gene and a -polypeptide, the product of the  gene. It was necessary, therefore, to change the concept of one gene-one enzyme to one gene-one polypeptide.