Biology Biomolecules SZABMU 2024 Reconduct
PMDC Verified Question 33 of 142
Which of the following is found in both messenger RNA and DNA of a mammalian cell?
A
Double helical structure
B
Ribose sugar
C
Thymine
D
Sugar phosphate backbone
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Sugar phosphate backbone
Concept:

DNA and RNA serve vastly different cellular functions, but they share the exact same fundamental polymer architecture.

Solution:

  • Both DNA and RNA are classified broadly as nucleic acids.


  • As such, they are both built by polymerizing nucleotides. Every single nucleotide, regardless of whether it's destined for DNA or RNA, connects to the next via a phosphodiester bond.


  • This creates a continuous, universal Sugar-phosphate backbone that forms the structural exterior of the molecule, serving as the universal scaffolding for both mRNA and DNA alike.


Why other options are incorrect:

  • Double helical structure: Found almost exclusively in DNA. Mammalian mRNA is inherently single-stranded.


  • Thymine: A base found exclusively in DNA (RNA replaces it with Uracil).


  • Ribose sugar: Found exclusively in RNA (DNA uses deoxyribose).

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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