NEETZoologyMolecular Basis of Inheritance
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The sequence of the coding strand in a transcription unit is the same as the transcribed RNA, except that thymine is replaced by uracil. Reason (R): During transcription, the RNA polymerase reads and copies the coding strand to synthesize the mRNA. In the light of the above statements, choose the m
Options
- AAssertion (A) is true but Reason (R) is false.
- BAssertion (A) is false but Reason (R) is true.
- CBoth Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- DBoth Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
Correct answer
A. Assertion (A) is true but Reason (R) is false.
Step-by-step solution
Assertion (A) is true. By convention, the DNA strand with 5' to 3' polarity is called the coding strand. Its sequence is identical to the newly synthesized mRNA, with the only difference being the presence of thymine (T) in DNA and uracil (U) in RNA. Reason (R) is false. During transcription, RNA polymerase binds to the promoter and reads the template strand (which has 3' to 5' polarity), not the coding strand. The coding strand does not code for anything and is displaced during the process. It is merely a referenc