NEETChemistryBiomolecules
Which of the following correctly describes the structure of a nucleotide that is found exclusively in DNA?
Options
- AA unit containing thymine attached to the 1' position of -D-2-deoxyribose, which is further linked to phosphor
- BA unit containing uracil attached to the 1' position of -D-ribose, which is further linked to phosphoric acid
- CA unit containing thymine attached to the 1' position of -D-2-deoxyribose, which is further linked to phosphor
- DA unit containing thymine attached to the 5' position of -D-2-deoxyribose, which is further linked to phosphor
Correct answer
A. A unit containing thymine attached to the 1' position of -D-2-deoxyribose, which is further linked to phosphor
Step-by-step solution
A nucleotide is formed when a nitrogenous base is attached to the 1' position of a pentose sugar, and phosphoric acid is linked to the 5' position of the sugar. DNA exclusively contains the nitrogenous base thymine (whereas RNA contains uracil) and the pentose sugar -D-2-deoxyribose (whereas RNA contains -D-ribose). Therefore, a nucleotide found exclusively in DNA consists of thymine attached to the 1' position of -D-2-deoxyribose, with phosphoric acid linked at the 5' position. Option 2 describes an RNA nucleotide