Q.51 Nucleotides, Nucleosides, purines and pyrimidines are the building blocks of DNA and RNA.
Based on their molecular weight, arrange these molecules in an ascending order.

A. Purine
B. Nucleotide
C. Pyrimidine
D. Nucleoside
E. Phosphate

Choose the correct answer from the options given below:

1. A, C, D, B, E
2. A, B, C, D, E
3. E, A, D, B, C
4. E, C, A, D, B

   Phosphate has the lowest molecular weight, followed by pyrimidine, purine, nucleoside, and nucleotide in ascending order.

   Question Breakdown

   The query asks to arrange purine (A), nucleotide (B), pyrimidine (C), nucleoside (D), and phosphate (E) by molecular weight from lowest to highest. These are key components of DNA/RNA: purines/pyrimidines are nitrogenous bases, nucleosides add sugar to bases, nucleotides add phosphate to nucleosides.

   Molecular Weights Explained

   Phosphate (PO4^2- or HPO4^2-) is ~95 Da, the smallest unit. Pyrimidines (e.g., cytosine ~111 Da, thymine ~126 Da) have single-ring structures and weigh less than purines. Purines (adenine ~135 Da, guanine ~151 Da) feature double rings, increasing mass. Nucleosides (base + deoxyribose ~130 Da sugar) range ~250-280 Da (e.g., deoxyadenosine ~251 Da). Nucleotides add phosphate (~3 phosphates in triphosphate form, avg. ~500 Da like ATP 507 Da), making them heaviest.

   Correct Sequence

   Order: E (95 Da) < C (~120 Da) < A (~140 Da) < D (~260 Da) < B (~500 Da). Matches option E, C, A, D, B.

   Nucleotides, nucleosides, purines, and pyrimidines serve as the core building blocks of DNA and RNA, with their molecular weights dictating size-based arrangements in exams. Understanding the nucleotides nucleosides purines pyrimidines molecular weight order is essential for molecular biology students preparing for competitive tests like GATE Life Sciences.​

   Structures and Components

   • Phosphate: Simplest at ~95 g/mol (HPO4^2-), links sugars in backbone.​

   • Pyrimidine bases (cytosine 111 Da, uracil/thymine ~126 Da): Single-ring, lightest nitrogenous bases.

   • Purine bases (adenine 135 Da, guanine 151 Da): Double-ring, heavier than pyrimidines.​

   • Nucleoside: Base + sugar (ribose/deoxyribose ~130 Da), e.g., adenosine ~267 Da.​

   • Nucleotide: Nucleoside + 1-3 phosphates, avg. 300-500 Da (ATP 507 Da).

   This hierarchy reflects added complexity: phosphate < base < base+sugar < base+sugar+phosphate.​

   Ascending Molecular Weight Order

   1. Phosphate (E, ~95 Da)

   2. Pyrimidine (C, ~111-126 Da)

   3. Purine (A, ~135-151 Da)

   4. Nucleoside (D, ~250-280 Da)

   5. Nucleotide (B, ~300-500+ Da)

   For DNA/RNA, average nucleotide monophosphate is ~330 Da, but triphosphates (polymerization form) exceed 480 Da. Use this for matching questions: E < C < A < D < B.

   Exam Tips

   Practice with averages: pyrimidines < purines due to rings; nucleotides heaviest from phosphate addition. Relate to techniques like electrophoresis, where size/mass separates them.​