A healthy couple with a history of three previous spontaneous abo...

Question

A healthy couple with a history of three previous spontaneous abortions has just had a child with cri-du-chat syndrome, a disorder caused by a terminal deletion of chromosome 5. Their physician orders karyotype analysis of both parents and of the child. The karyotype results for chromosomes 5 and 12 are shown here.

What segregation pattern occurred to produce the gamete involved in fertilization of the child with cri-du-chat syndrome?

Accepted Answer

Hello, everyone and welcome to today's video. So if the Caro type analysis of a couple shows the female having a deletion at the terminal end of the five P arm, what could be the type overly segregation that may cause the offspring to have syndrome? As answer choice. A we have this junction followed by equal crossing over as answer choice B we have nondisjunction followed by equal crossing over as answer choice C we have nondisjunction followed by unequal crossing over and as answer choice D we have disjunction followed by equal crossing over. Now, the type of allele segregation that usually causes an offspring to have syndrome is going to be nondisjunction then followed by unequal crossing over. But why now nondisjunction is going to refer to the failure of homologous chromosomes or C orchids to separate properly during meiosis. And this is going to result in gametes with an abnormal number of chromosomes, unequal crossing over. On the other hand refers to an error that can occur during crossing over which can result in one chromosome having an extra copy of a particular DNA segment while the other is missing certain parts of its chromosome, certain parts of its DNA. So we know that syndrome is going to be the missing or just an organism missing a peace of a particular chromosome. So this unequal crossing over is going to end up resulting in that. Therefore, our correct answer choice here is going to be answer choice none disjunction followed by unequal crossing over. I really hope this video helped you and I hope to see you on the next one.

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