2017 · Q1
Polynucleotide chain of DNA contains
General KnowledgeBiology
- Aa nitrogenous base, deoxyribose sugar and phosphate group.
- Ba nitrogenous base, ribose sugar and phosphate group.
- Cdeoxyribose sugar, ribose sugar and phosphate group.
- Da nitrogenous base and phosphate group only.
Explanation
A DNA nucleotide consists of a nitrogenous base (adenine, guanine, cytosine, or thymine), the pentose sugar deoxyribose (which lacks the 2'-OH group of ribose), and a phosphate group. In a polynucleotide chain, these nucleotides are linked by phosphodiester bonds between the 3' carbon of one deoxyribose and the 5' phosphate of the next. Option B describes an RNA nucleotide (ribose sugar), C wrongly includes both sugars, and D omits the sugar entirely. Hence A.