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Genetics Exam Review Problem on Mitosis and Meiosis

A woman is know to be carrying a severe recessive autosomal gene. It is possible to determine whether a cell or poloar body is carrying the normal or dissorder recessive. The detection procedure destroys the ovum.

She has opted for in vitro fertilization so the the egg and sperm can be united in a test tube. To avoid having to select a normal embryo and destroy others, she wants to be certain the egg is not carrying the mutation. It is possible to have the oocyte continue meiosis in a test tube.

What would you want to see in the poloar body at the first meiotic division? What would you want to see in the second meitoic division? You must be able to diagram oogenesis and segregation of the genes. Do not give probabilities, only certainy.

Solution Preview

Remember that in the first step of meiosis, an oocyte divides, with one set of homologous chromosomes going into each of the daughter cells. One of those cells will get the majority of the cytoplasm, and will go on to divide again in the second step of meiosis, while the other daughter cell will become a polar body. At the second step of meiosis, the sister chromatids separate to form an ovum with one set of single-chromatid chromosomes, while the other part of the cell from that division becomes another polar body.
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<br>So, assume that the woman who wishes to become pregnant is only carrying one ...

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