Target Exam

CUET

Subject

Chemistry

Chapter

Organic: Biomolecules

Question:

Identify the sequence of bases of m-RNA molecule synthesised on the given strand of DNA AGCGATTAC.

Options:

ACGCATTAG

TGGCTAATG

UCGCUAAUG

UCGCUTTUC

Correct Answer:

UCGCUAAUG

Explanation:

The correct answer is Option (3) → UCGCUAAUG.

In transcription, mRNA is synthesized using a DNA template strand. The rules of base pairing are:

Adenine (A) pairs with Uracil (U) in RNA (instead of Thymine (T) in DNA),

Thymine (T) pairs with Adenine (A),

Cytosine (C) pairs with Guanine (G), and

Guanine (G) pairs with Cytosine (C).

The given DNA strand is:

\(\text{DNA: } 5' - AGCGATTAC - 3'\)

Steps for transcription:

Pair the complementary RNA bases with the DNA template:

  • A → U
  • G → C
  • C → G
  • G → C
  • A → U
  • T → A
  • T → A
  • A → U
  • C → G


Thus, the sequence of bases on the mRNA will be:

\(\text{mRNA: } 5' - UCGCUAAUG - 3'\)

Conclusion:

The correct sequence of the mRNA molecule synthesized is: option (3): UCGCUAAUG.