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Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYMolecular Basis of Inheritance1 Mark
Question
For question, two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
  2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
  3. Assertion is true, but reason is false.
  4. Both assertion and reason are false.

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 polypeptides.

✓

Answer

  1. Both assertion and reason are true, and reason is the correct explanation of assertion.

Explanation:

In 1948, Beadle and Tatum proposed that a gene controls the synthesis of one enzyme. But, many enzymes, as well as the haemoglobins 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. coli, for example, contains an $\alpha$ polypeptide, the product of the trp A gene and $\beta$ polypeptide, the product of the $\beta$ gene It was necessary, therefore, to change the concept of one gene-one enzyme to one gene-one polypeptide.

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