Directions: In the following questions a statement of assertion (A) i...
The sequence of mRNA will be identical to the given sequence of coding strand except for the presence of uracil in place of thymine in mRNA.
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Directions: In the following questions a statement of assertion (A) i...
Assertion (A): The newly formed mRNA has the same sequence as the coding strand of the transcriptional unit with uracil present at place of thymine.
Reason (R): The rule of complementarity guides the formation of DNA and RNA.
Explanation:
- During transcription, the DNA molecule is used as a template to synthesize an RNA molecule. The process involves the synthesis of a complementary RNA molecule based on the DNA sequence.
- The DNA molecule consists of two strands, the coding strand and the template strand. The coding strand has the same sequence as the newly formed mRNA, except that it contains thymine (T) instead of uracil (U).
- The template strand is the complementary strand to the coding strand and is used as a template during transcription. The RNA polymerase enzyme adds nucleotides to the growing mRNA molecule based on the complementary base pairing rule.
- The rule of complementarity states that adenine (A) pairs with uracil (U) in RNA, and cytosine (C) pairs with guanine (G). Therefore, during transcription, when the RNA polymerase encounters an adenine (A) on the template strand, it adds a uracil (U) to the growing mRNA molecule.
- As a result, the newly formed mRNA molecule has the same sequence as the coding strand of the transcriptional unit, with uracil (U) present in place of thymine (T).
- Therefore, both the assertion (A) and the reason (R) are true. The reason (R) correctly explains why the newly formed mRNA has the same sequence as the coding strand of the transcriptional unit with uracil present at the place of thymine.
- Hence, the correct answer is option A.
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