The pyrimidine base that is present in RNA is?

Appeared in: DSSSB -28 August 2019 (Shift-2)

Explanation

The question asks to identify the pyrimidine base present in RNA.
Nitrogenous bases are classified as purines (Adenine, Guanine) and pyrimidines (Cytosine, Thymine, Uracil).
RNA contains the purine bases Adenine and Guanine, and the pyrimidine bases Cytosine and Uracil.
Uracil is the unique pyrimidine base in RNA, replacing Thymine which is found in DNA.
Therefore, among the given options, Uracil is the correct pyrimidine base found in RNA.

Option A: Adenine is a purine, characterized by a double-ring structure, not a pyrimidine which has a single-ring structure.
Option B: Thymine is a pyrimidine base, but it is exclusively found in DNA, not in RNA.
Option D: Guanine is a purine, not a pyrimidine. The question specifically asks for a pyrimidine base.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Structure and components of RNA, specifically pyrimidine bases as background academic context rather than a clinical decision trigger.
Understanding the structural differences between DNA and RNA, such as the presence of Uracil in RNA, is fundamental to molecular biology, genetics, and pharmacology.
Many antiviral drugs, such as those used to treat HIV (e.g., Zidovudine/AZT) or Hepatitis C, are nucleoside analogs that interfere with viral RNA or DNA replication by targeting these unique structural components.
The distinct composition of RNA is crucial for its diverse roles, including acting as a messenger (mRNA), a component of ribosomes (rRNA), and a transfer molecule for amino acids (tRNA) during protein synthesis.

How to Approach the Question

First, identify the key terms in the question: 'pyrimidine base' and 'RNA'.
Recall the two main categories of nitrogenous bases: purines (double-ring structure) and pyrimidines (single-ring structure).
Remember the specific bases in each category: Purines are Adenine (A) and Guanine (G); Pyrimidines are Cytosine (C), Thymine (T), and Uracil (U).
Recall the base composition of DNA (A, T, C, G) and RNA (A, U, C, G).
Analyze the options based on this knowledge. Eliminate Adenine and Guanine as they are purines.
Differentiate between the remaining pyrimidines, Thymine and Uracil. Thymine is in DNA, and Uracil is in RNA.

Concept Tested & Keywords

Qj0cpZ5xTHBW-FNMIHgFy_

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 2 — Subpart A (pp 1-239 of 478) p. 216-218

E6 Biochemistry U Satyanarayana— Part 1 (pp 26-420 of 840) p. 61-63

Practise the full DSSSB -28 August 2019 (Shift-2)

Attempt every question from this paper in a timed mock, then review the full solution for each one.