VKC ScienceChemistry for written exams Telegram

UPSC Civil Services (Mains)

Chemistry optional

  • 2 papers
  • 250 marks each
  • 3 h per paper
  • 5 of 8 questions, Q1 and Q5 compulsory

Paper II covers organic chemistry and spectroscopy.

UPSC Civil Services (Mains), Chemistry optional · 2022 · Paper II

Q5(a). Nucleosides, nucleotides and the primary structure of DNA and RNA

Question

Write the structures of nucleosides and nucleotides, and discuss the primary structures of DNA and RNA.

Answer in brief

Nucleoside = base + pentose (β-N-glycosidic bond); nucleotide = nucleoside + phosphate (ester at 5′-OH); primary structure is the nucleotide sequence linked by 3′,5′-phosphodiester bonds, read 5′ → 3′.

Part of VKC Basic

Read the key points and the full model answer with VKC Basic

VKC Basic (₹999 for 6 months) opens every solved answer, the notes, the handbook and the daily answer archive. Every Mains test series includes it.

See what is included Already a member? Sign in

The full model answer

As written for the answer booklet: the diagram carries the working, the lines stay short. Read here only; it is not offered as a download.

The handwritten model answer pages open with the VKC plan.
Read the whole 2022 solution2022 question paper

Topic notes: biopolymers: proteins, peptides, DNA and RNA, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversnucleosidenucleotidephosphodiester bondprimary structure of DNARNAglycosidic bond

All parts of Question 5