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Molecular Basis of Inheritance question

2024 · Q36
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Molecular Basis of Inheritance question

2024 · Q36

NEETBiologyMolecular Basis of InheritanceMCQ+4 / −1

Given below are two statements :

Statement I: In the lac operon, the z gene codes for beta-galactosidase which is primarily responsible for the hydrolysis of lactose into galactose and glucose.

Statement II: In addition to lactose, glucose or galactose can also induce lac operon.

In the light of the above statements, choose the correct answer from the options given below :

  1. A
    Statement I is true but Statement II is false
  2. B
    Statement I is false but Statement II is true
  3. C
    Both Statement I and Statement II are true
  4. D
    Both Statement I and Statement II are false
View written solutionFree

Correct answer: A

Let's examine both statements to determine their validity.

Statement I: In the lac operon, the z gene codes for beta-galactosidase which is primarily responsible for the hydrolysis of lactose into galactose and glucose.

Explanation: This statement is correct. The lac operon in E. coli consists of three structural genes: lacZ, lacY, and lacA. The lacZ gene encodes for the enzyme beta-galactosidase, which catalyzes the hydrolysis of lactose into glucose and galactose.

Statement II: In addition to lactose, glucose or galactose can also induce lac operon.

Explanation: This statement is incorrect. The lac operon is specifically induced by lactose or allolactose (an isomer of lactose), which act as inducers by deactivating the lac repressor. Glucose, on the other hand, represses the lac operon through catabolite repression, a mechanism that ensures the operon is not expressed when glucose is available. Galactose does not serve as an inducer for the lac operon.

Based on the explanations above, we can conclude that:

Option A: Statement I is true but Statement II is false

Thus, the correct answer is:

Option A

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