[Campbell Biology P.335] What is the underlying molecular cause of cystic fibrosis? | Practice Question

What is the underlying molecular cause of cystic fibrosis?

  • A: A substitution of a single amino acid in the hemoglobin protein.
  • B: Defective or absent chloride transport channels in plasma membranes.
  • C: An unusually high frequency of heterozygotes in the population.
  • D: The aggregation of hemoglobin proteins into long fibers under low oxygen.

Explanation

The text clearly states that the normal allele for the cystic fibrosis gene codes for a membrane protein that transports chloride ions. In affected individuals, these channels are 'defective or absent,' leading to the symptoms of the disease.