Question

The diagram to the right shows a pair of replicated, homologous chromosomes in the nucleus of a human primary oocyte. As it proceeds through meiosis, this cell next becomes a secondary oocyte containing one polar body, and then a mature ovum (egg cell) with two polar bodies. The female who produced this oocyte is heterozygous for a dominant disease allele, D. The wildtype allele of this gene is indicated by "+". Polar bodies are not absolutely necessary for embryo development. Methods exist to detect whether a D or + allele is present in a polar body and how many copies are present. A geneticist is considering whether removing and analysing one of the polar bodies would allow her to predict if the ovum would produce a child affected by the disease. Use a diagram(s) based on the drawing above to discuss whether this is possible 14 marks]

Answer 1

yes it is possible to detect weather the child is affected by the disease or not, because as shown in the figure uploaded there are two possible cases for the division of primary oocyte mentioned in the question.

Case 오 8 tpelax boday 1st Powe body matuue OVum and polau bodly

Case 1: In oogenesis among the two polar bodies if the one under detection is diploid and contains wild type genes then surely the child produced by the ovum will be affected by the disease.

If the polar body under detection is haploid and contains D allele then also it is sure that the ovum contains D allele too and the child produced by this ovum will have disease. (as shown in the image)

Case 2: If the polar body under detection is diploid and contains D allele then it is sure that ovum producing child is normal and having + allele.

If the polar body under detection is haploid and contains + allele then also its sure that ovum contains wild type allele too.