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NEETZoologyPrinciples of Inheritance and Variation

Read the following statements carefully regarding sickle-cell anaemia: (I) It is an autosome linked recessive trait that can be transmitted from parents to the offspring when both the partners are carrier for the gene. (II) The defect is caused by the substitution of Glutamic acid by Valine at the sixth position of the beta globin chain of the haemoglobin molecule. (III) The mutant haemoglobin molecule undergoes poly

Options

  1. AOne
  2. BTwo
  3. CThree
  4. DFour

Correct answer

C. Three

Step-by-step solution

Statement (I) is correct: Sickle-cell anaemia is an autosome linked recessive trait. Statement (II) is correct: The molecular basis of the disease is a point mutation leading to the substitution of Glutamic acid (Glu) by Valine (Val) at the sixth position of the beta globin chain. Statement (III) is incorrect: The mutant haemoglobin molecule undergoes polymerisation under LOW oxygen tension, not high oxygen tension. This polymerisation changes the RBC shape from a biconcave disc to an elongated sickle-like structur

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