Anaphase promoting complex (APC) is a protein degradation machinery necessary for proper mitosis of animal cells. If APC is defective in a human cell, which of the following is expected to occur?
Answer: (C) Chromosomes will not segregate. Answer: Chromosomes will not segregate Solution: The Anaphase Promoting Complex (APC) triggers degradation of proteins that hold sister chromatids together, allowing the centromeres to split and chromatids to move to opposite poles during anaphase; if APC is defective, this separation cannot occur and chromosomes will not segregate.
- A.Chromosomes will not condense
- B.Chromosomes will be fragmented
- C.Chromosomes will not segregate✓
- D.Recombination of chromosome arms will occur
Correct Answer
(C) Chromosomes will not segregate
Solution & Explanation
Answer: Chromosomes will not segregate Solution: The Anaphase Promoting Complex (APC) triggers degradation of proteins that hold sister chromatids together, allowing the centromeres to split and chromatids to move to opposite poles during anaphase; if APC is defective, this separation cannot occur and chromosomes will not segregate. Chromosome condensation (prophase) and nuclear-membrane breakdown happen before APC acts, so they are unaffected, and APC does not fragment chromosomes or cause recombination of arms (a meiotic crossing-over event). (APC is a NEET extension; the NCERT text describes anaphase as centromere splitting and chromatid separation.) NCERT Reference: Ch 10, p.124, line 5 — "Centromeres split and chromatids separate."