Genetics: From Genes to Genomes
6th Edition
ISBN: 9781259700903
Author: Leland Hartwell Dr., Michael L. Goldberg Professor Dr., Janice Fischer, Leroy Hood Dr.
Publisher: McGraw-Hill Education
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Chapter 4, Problem 5P
Researchers discovered recently that the sole function of the SRY protein is to activate an autosomal gene called 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 |
| b. | Given your answer to part (a), why is SRY, rather than Sox9, considered the male determining factor? (Hint: What do you think would happen if you did an experiment like the one in the Fast Forward Box Transgenic Mice Prove That SRY Is the Maleness Factor, except that you used a Sox9 transgene instead of SRY?) |
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. 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.
Suppose a man carries a very uncommon dominant mutation for a deadly muscular disease that doesn't show up until people are usually over 50 years of age (he has the disease). He and his wife are expecting their first child--a girl. What is the probability she will also have the disease if...
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Chapter 4 Solutions
Genetics: From Genes to Genomes
Ch. 4 - Choose the best matching phrase in the right...Ch. 4 - Humans have 46 chromosomes in each somatic cell....Ch. 4 - The figure that follows shows the metaphase...Ch. 4 - Human XX males who are sex-reversed because they...Ch. 4 - Researchers discovered recently that the sole...Ch. 4 - One oak tree cell with 14 chromosomes undergoes...Ch. 4 - Indicate which of the cells numbered iv matches...Ch. 4 - a. What are the four major stages of the cell...Ch. 4 - Answer the questions that follow for each stage of...Ch. 4 - Can you think of anything that would prevent...
Ch. 4 - One oak tree cell with 14 chromosomes undergoes...Ch. 4 - Which types of cell division mitosis, meiosis I,...Ch. 4 - Complete the following statements using as many of...Ch. 4 - The five cells shown in figure a e are all from...Ch. 4 - One of the first microscopic observations of...Ch. 4 - A person is simultaneously heterozygous for two...Ch. 4 - Assuming i that the two chromosomes in every...Ch. 4 - In the moss Polytrichum commune, the haploid...Ch. 4 - Can you think of anything that would prevent...Ch. 4 - Sister chromatids are held together through...Ch. 4 - The pseudoautosomal regions PARs of the X and Y...Ch. 4 - Remarkably, the platypus has 10 sex chromosomes,...Ch. 4 - Somatic cells of chimpanzees contain 48...Ch. 4 - In humans: a. How many sperm develop from 100...Ch. 4 - Women sometimes develop benign tumors called...Ch. 4 - In a certain strain of turkeys, unfertilized eggs...Ch. 4 - Imagine you have two pure-breeding lines of...Ch. 4 - A system of sex determination known as...Ch. 4 - In Drosophila, the autosomal recessive brown eye...Ch. 4 - Barred feather pattern is a Z-linked dominant...Ch. 4 - When Calvin Bridges observed a large number of...Ch. 4 - In a vial of Drosophila, a research student...Ch. 4 - In 1919, Calvin Bridges began studying an X-linked...Ch. 4 - In Drosophila, a cross was made between a...Ch. 4 - As we learned in this chapter, the white mutation...Ch. 4 - The following is a pedigree of a family in which a...Ch. 4 - Each of the four pedigrees that follow represents...Ch. 4 - The pedigree that follows indicates the occurrence...Ch. 4 - Duchenne muscular dystrophy DMD is caused by a...Ch. 4 - The X-linked gene responsible for DMD encodes a...Ch. 4 - Males have hemophilia when they are hemizygous for...Ch. 4 - In the Fast Forward Box Visualizing X Chromosome...Ch. 4 - Consider the following pedigrees from human...Ch. 4 - Several different antigens can be detected in...Ch. 4 - The ancestry of a white female tiger bred in a...Ch. 4 - The pedigree that follows shows the inheritance of...Ch. 4 - In 1995, doctors reported a Chinese family in...Ch. 4 - In cats, the dominant O allele of the X-linked...Ch. 4 - In marsupials like the opposum or kangaroo, X...Ch. 4 - The pedigree diagram below shows a family in which...
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- XX individuals can be sex-reversed males if one of their X chromosomes contains a translocated portion of the Y chromosome that includes the SRY gene. In light of what you now know about X-chromosome inactivation, it seems that this karyotype might have more complex consequences. In fact, although most such males are completely sex-reversed, X-chromosome inactivation can cause some of these XX males to have varying degrees of residual female characteristics. a. X-chromosome inactivation in normal XX embryos occurs earlier in development than SRY production in normal XY embryos. When present on a translocation X chromosome, SRY is subject to inactivation. Formulate a hypothesis to explain why many XX individuals with a translocation X chromosome that includes the SRY gene are not completely sex-reversed (male). b. Based on your answer to part (a), why do you think some individuals with this karyotype are completely sex-reversed?arrow_forwardIn drosophila, a recessive mutation (m-) of a maternal effect gene results in an abnormal phenotype wherein homozygous (m-m-) females produce eggs that cannot support embryonic development. Homozygous (m-m-) males, however, can still produce viable sperm. (A) Using m+ to denote a normal gene, determine the genotypes and phenotypes of the F1s produce by a cross between a heterozygous female and a recessive male. (B) From the offspring, backcross the recessive female with the paternal strain. What are the genotypes and phenotypes of the F2s? (C) If m-m- females produce useless eggs, then how are m-m- produced?arrow_forwardA man who is a carrier of a translocated 15/21 chromosome marries a genotypically normal woman. a. Show the possible gametes that will be formed by this man if the translocated 15/21 chromosome synapses with chromosome 21 at Prophase I.arrow_forward
- The somatic cells of most individuals with Down syndrome contain an extra chromosome 21, for a total of forty-seven chromosomes. a. At which stage(s) of meiosis could nondisjunction alter the chromosome number? b. A few individuals with Down syndrome have forty-six chromosomes: two normal-appearing chromosomes 21, and a longer-than-normal chromosome 14. Speculate on how this chromosome abnormality may arise.arrow_forwardA male Drosophila melanogaster has the genotype A/a; B/b; C/c; XD/Y (all genes are on separate chromosomes). How many different sperm genotypes can it produce through meiosis of one single pre-gametic (2n) cell? (remember, there is no crossing over in male Drosophila) Explain.arrow_forwardHemophilia A is caused by a sex-linked recessive gene in human and in dogs. a. What proportions (and sexes), among their offspring will be hemophiliacs if a hemophilic male is mated to a homozygous nonhemophilic female?b. If a daughter produced by the mating in (a) is mated to a normal male, what proportions and (sexes) will be hemophilic among their offspring?arrow_forward
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