Question:
Which ONE of the following options is CORRECT with respect to sequential breakdown of deoxyribonucleic acid (DNA) into lower-molecular weight compounds?
Which ONE of the following options is CORRECT with respect to sequential breakdown of deoxyribonucleic acid (DNA) into lower-molecular weight compounds?
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Remember that a nucleotide loses its phosphate to become a nucleoside, and a nucleoside then splits into its sugar (2-deoxyribose) and base; reverse-engineer the breakdown order from this build-up.
Updated On: Jul 20, 2026
- Deoxyribonucleic acid → 2-deoxyribose → Nucleosides → Nucleotides
- Deoxyribonucleic acid → 2-deoxyribose → Nucleotides → Nucleosides
- Deoxyribonucleic acid → Nucleotides → Nucleosides → 2-deoxyribose
- Deoxyribonucleic acid → Nucleosides → Nucleotides → 2-deoxyribose
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The Correct Option is C
Solution and Explanation
Step 1: Recall the structural hierarchy of DNA. DNA is a polymer built from repeating nucleotide units, and each nucleotide itself is built from a nucleoside (a sugar joined to a nitrogenous base) plus a phosphate group.
Step 2: Identify the first breakdown step. Enzymatic hydrolysis (by nucleases such as DNases) first cleaves the phosphodiester backbone of the DNA polymer, breaking it down into its repeating monomer units, the nucleotides (sugar-phosphate-base units).
Step 3: Identify the second breakdown step. Nucleotidases then remove the phosphate group from each nucleotide, converting nucleotides into nucleosides (sugar joined only to the base, phosphate removed).
Step 4: Identify the final breakdown step. Nucleosidases finally cleave the bond between the sugar and the nitrogenous base, releasing the free sugar, 2-deoxyribose (and the free base) from the nucleoside.
Step 5: Assemble the full sequence and eliminate wrong options. The correct order is therefore Deoxyribonucleic acid -> Nucleotides -> Nucleosides -> 2-deoxyribose, which is option (C). Options (A) and (B) incorrectly place 2-deoxyribose right after DNA, before the phosphate and base have even been separated out, which is not physically possible since 2-deoxyribose is the smallest, final breakdown product. Option (D) incorrectly reverses the order of nucleosides and nucleotides.
Step 2: Identify the first breakdown step. Enzymatic hydrolysis (by nucleases such as DNases) first cleaves the phosphodiester backbone of the DNA polymer, breaking it down into its repeating monomer units, the nucleotides (sugar-phosphate-base units).
Step 3: Identify the second breakdown step. Nucleotidases then remove the phosphate group from each nucleotide, converting nucleotides into nucleosides (sugar joined only to the base, phosphate removed).
Step 4: Identify the final breakdown step. Nucleosidases finally cleave the bond between the sugar and the nitrogenous base, releasing the free sugar, 2-deoxyribose (and the free base) from the nucleoside.
Step 5: Assemble the full sequence and eliminate wrong options. The correct order is therefore Deoxyribonucleic acid -> Nucleotides -> Nucleosides -> 2-deoxyribose, which is option (C). Options (A) and (B) incorrectly place 2-deoxyribose right after DNA, before the phosphate and base have even been separated out, which is not physically possible since 2-deoxyribose is the smallest, final breakdown product. Option (D) incorrectly reverses the order of nucleosides and nucleotides.
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