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UPSC Civil Services (Mains)

Chemistry optional

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

Paper I covers physical and inorganic chemistry.

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

Q5(c). Allosteric effect and homotropic modulators

Question

What is allosteric effect? Give example of an allosteric protein. Discuss homotropic allosteric modulators with examples.

Answer in brief

Allosteric effect: a ligand bound at one site of a protein changes its shape and so its affinity or activity at another site; example haemoglobin, where O₂ bound at one haem raises the O₂ affinity of the other three.

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Topic notes: bio-inorganic chemistry (haemoglobin, cytochromes, Fe–S proteins, ion pumps), with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversallosteric effecthomotropic modulatorhaemoglobin cooperativityT and R statesHill coefficientsigmoid binding curve

All parts of Question 5