[Campbell Biology P.1078] Based on the "WHAT IF?" scenario, if a woman carries a mutation in ... | Practice Question

Based on the "WHAT IF?" scenario, if a woman carries a mutation in a disease gene, would analyzing the DNA of the first polar body allow you to infer whether the mutation is present in the mature oocyte? Explain.

  • A: Yes, because polar bodies are genetically identical to the oocyte.
  • B: Yes, because both the mature oocyte and the first polar body originate from the same primary oocyte and undergo meiosis I, so they would share complementary genetic material for inference.
  • C: No, because polar bodies contain different genetic material due to unequal cytokinesis.
  • D: No, because the first polar body degenerates quickly, making DNA analysis impossible.

Explanation

A primary oocyte 2n undergoes Meiosis I, where homologous chromosomes separate. The first polar body receives one set of homologous chromosomes n, each with two chromatids , and the secondary oocyte receives the other. Since they both originate from the same primary oocyte and meiosis I separates homologous pairs, analyzing the DNA of the first polar body allows you to infer the genetic composition of the homologous chromosome that went into the secondary oocyte and eventually the mature oocyte . For instance, if the woman is heterozygous for a mutation, and the polar body receives the mutated allele, then the oocyte must have received the normal allele.