Over a period of two years, a man in his early 20s received a series of intermittent chemotherapy and radiotherapy treatments for Hodgkin disease. During this therapy, he and his wife were unable to initiate a pregnancy. The man had a series of his semen samples examined at a fertility clinic. The findings revealed that shortly after each treatment very few mature sperm were present, and abnormal chromosome numbers were often observed in developing spermatocytes. However, such chromosome abnormalities disappeared about 40 days after treatment, and normal sperm reappeared about 74 days post-treatment. Do you think that exposure to chemotherapy and radiotherapy would cause more problems to spermatocytes than to mature sperm?
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Concepts of Genetics (12th Edition)
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- Human sex chromosomes are XX for females and XY for males. a. With respect to an X-linked gene, how many different types of gametes can a male produce? b. If a female is homozygous for an X-linked allele, how many different types of gametes can she produce with respect to this allele? c. If a female is heterozygous for an X-linked allele, how many different types of gametes can she produce with respect to this allele?arrow_forwardJan is concerned about using ART. She wants to be the genetic mother and have Darryl be the genetic father of any children they have. What methods of ART would you recommend to this couple? Jan, a 32-year-old woman, and her husband, Darryl, have been married for 7 years. They have attempted to have a baby on several occasions. Five years ago, they had a first-trimester miscarriage, followed by an ectopic pregnancy later the same year. Jan continued to see her OB/GYN physician for infertility problems but was very dissatisfied with the response. After four miscarriages, she went to see a fertility specialist, who diagnosed her with severe endometriosis and polycystic ovarian disease (detected by hormone studies). The infertility physician explained that these two conditions were hampering her ability to become pregnant and thus making her infertile. She referred Jan to a genetic counselor. At the appointment, the counselor explained to Jan that one form of endometriosis (MIM 131200) can be a genetic disorder, and that polycystic ovarian disease can also be a genetic disorder (MIM 184700) and is one of the most common reproductive disorders among women. The counselor recommended that a detailed family history of both Jan and Darryl would help establish whether Jans problems have a genetic component and whether any of her potential daughters would be at risk for one or both of these disorders. In the meantime, Jan is taking hormones, and she and Darryl are considering alternative modes of reproduction. Using the information in Figure 16.4, explain the reproductive options that are open to Jan and Darryl.arrow_forwardWhat is the probability for a spermatozoid to receive only maternal chromosomes (that were given by the mother of this man) ?arrow_forward
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- In the process of Oogenesis in animal cells, will the genotype of the second polar body (derived from meiosis II) always be identical to that of the ootid? Why or why not?arrow_forwardWhy are newborns with an abnormal sex chromosome number more likely to survive than those with an abnormal autosome number?arrow_forward. Researchers discovered recently that the sole functionof the SRY protein is to activate an autosomal genecalled Sox9 in the presumptive gonad (before it has“decided” to become a testis or an ovary).a. What would be the sex of an XY individual homozygous for nonfunctional mutant alleles of Sox9?Explain.arrow_forward
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