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Friday, 9 October

JEE Main 2021 · ChemistryMultiple choiceDiagram basedMediumDiagram reading

JEE Main 3 August 2021, Shift 2, Chemistry Q50

Question 50 of 90 in this shift, Chemistry question 20 of 30, Section A.

Which one of the following represents the correct structure of a dinucleotide?

The figure, in words

Options are four structural drawings of dinucleotides (sugar rings with 'Base' boxes joined by phosphate groups).
  1. (1)[figure: dinucleotide; first sugar bears 5'-phosphate (-O2P(=O)O- ... ) and its 3'-O is linked through a phosphate (O-P(=O)(O-)-O) to the 5'-CH2-O of the second sugar; each sugar carries a Base box; second sugar has two OH groups]Official answer
  2. (2)[figure: two sugar units each with a Base; a single phosphate (O-P(=O)-O-) joins the 5'-O of the first sugar to the 5'-O of the second sugar; sugars carry OH groups at 2' and 3']
  3. (3)[figure: dinucleotide; first sugar bears a 5'-phosphate (-O-P(=O)(O-)-) and its 3'-O is linked through a phosphate to the 5'-CH2-O of the second sugar; each sugar carries a Base box; second sugar has two OH groups]
  4. (4)[figure: two sugar units each with a Base; two phosphate groups (P-O-P, pyrophosphate-like) join the 5'-O of the first sugar to the 5'-O of the second sugar; sugars carry OH groups at 2' and 3']

Official answer

Option 1

NTA final key.

Chapter
Biomolecules
Topic
No close match in our taxonomy
Idea tested
No close match in our taxonomy

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.