In mice, the X-linked dominant mutation Testicular feminization (Tfm) eliminates the normal response to the testicular hormone testosterone during sexual differentiation. An XY mouse bearing the Tfm allele on the X chromosome develops testes, but no further male differentiation occurs–the external genitalia of such an animal are female. From this information, what might you conclude about the role of the Tfm gene product and the X and Y chromosomes in sex determination and sexual differentiation in mammals? Can you devise an experiment, assuming you can “genetically engineer” the chromosomes of mice, to test and confirm your explanation?
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Essentials of Genetics Plus Mastering Genetics with eText -- Access Card Package (9th Edition) (Klug et al. Genetics Series)
- 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_forwardSexual differentiation begins close to 4 weeks after fertilization, but cannot be seen visually until about 6 weeks post fertilization. All fetuses begin with a ______________________ gonad that is able to become either ovaries or testes, depending on the presence or absence of the Y chromosome. If the Y chromosome is present, a region of the Y chromosome will begin expressing genes that start the process of masculinization of internal structures. This region is known as the ______________________________ region or ___________ for short. The expression of these genes causes the bipotential gonad to develop into the testes. Once the testes have started developing, two hormones, testosterone and Anti-MüllerianHormone are produced. Testosterone causes the _____________________ ducts to develop into the _____________________. Testosterone also causes the internal development of the __________________ and __________________. Anti-Müllerian Hormone causes the ______________________ ducts…arrow_forwardWith relevance to sex determination in humans, discuss: i) X chromosome inactivation; and ii) Testicular feminization Provide detail examples.arrow_forward
- If a genetic female fetus is exposed to testosterone in utero, would that individual develop a complete male phenotypic sex, partial male phenotypic sex, or a normal female phenotypic sex? Explain your answer, describing the sex phenotype of the gonads, internal genital ducts and external genitalia. What would the developmental outcomes be if the fetus were instead exposed to dihydrotestosterone in utero?arrow_forwardIn humans, the AR gene is located on the X chromosome. If a person who is XY has a complete deletion of the AR gene, do you think giving them testosterone injections during puberty would cause an increase in expression of male secondary sex characteristics compared to not receiving injections? Explain your answer.arrow_forwardIn mice, the Sry gene is located on the Y chromosome very close to one of the pseudoautosomal regions that pairs with the X chromosome during male meiosis. Given this information, propose a model to explain the generation of unusual males who have two X chromosomes (with an Sry-containing piece of the Y chromosome attached to one X chromosome).arrow_forward
- What will be the effect on sexual development in newly fertilized Drosophila embryos if the following genes are deleted? Q. sex-lethalarrow_forwardGametogenesis in mammals is a complex process. When comparing spermatogenesis and oogenesis, indicated whether the follow statements are true or false. After the S phase, both the spermatogonial stem cell and primary oocyte have the same number of double-copy chromosomes. #analyze Question 1 options: True False Both the first polar body and the second polar body have the same number of chromosomes. #analyze Question 2 options: True False After the S phase, both the spermatogonial stem cell and primary oocyte have the same number of double-copy chromosomes. #analyze Question 3 options: True False Both the primary oocyte and the secondary spermatocyte have double-copy chromosomes. #analyze Question 4 options: True Falsearrow_forwardSuppose you are analyzing the DNA from the polar bodies formed during human oogenesis. If the woman who produced the oocyte has a mutation in a known disease gene, would analyzing the polar body DNA allow you to infer whether the mutation is present in the mature oocyte? Explain.arrow_forward
- Mutations Can Uncouple chromosomal Sex from Phenotypic Sex Discuss whether the following individuals (1) have male or female gonads, (2) are phenotypically male or female (discuss Wolffian/Mllerian ducts and external genitalia), and (3) are sterile or fertile. a. XY, homozygous for a recessive mutation in the testosterone biosynthetic pathway, producing no testosterone b. XX, heterozygous for a dominant mutation in the testosterone biosynthetic pathway, which causes continuous production of testosterone c. XY, heterozygous for a recessive mutation in the MIH gene d. XY, homozygous fora recessive mutation in the SRY gene that abolishes functionarrow_forwardWhat pathway is Fog2 gene product a part of and how does it affect sex determination?arrow_forwardWhat will be the effect on sexual development in newly fertilized Drosophila embryos if the following genes are deleted? Q. doublesexarrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning