GENETIC ANALYSIS: AN INTEG. APP. W/MAS
2nd Edition
ISBN: 9781323142790
Author: Sanders
Publisher: Pearson Custom Publishing
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Textbook Question
Chapter 3, Problem 26P
In humans, SRY is located near a pseudoautosomal region (PAR) of the Y chromosome, a region of homology between the X and Y chromosomes that allows them to synapse during meiosis in males and is a region of crossover between the chromosomes. The diagram below shows SRY in relation to the pseudoautosomal region.
About 1 in every 25,000 newborn infants is born with sex reversal; the infant is either an apparent male, but with two X chromosomes, or an apparent female, but with an X and a Y chromosome. Explain the origin of sex reversalin human males and females involving the SRY gene. (Hint: See Experimental Insight 3.1 for a clue about the mutational mechanism.)
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Butterflies have an X-Y sex-determination system that is different from that of flies or humans. Female butterflies may be either XY or X0, while butterflies with two or more X chromosomes are males. This photograph shows a tiger swallowtail gynandromorph, which is half male (left side) and half female (right side). Given that the first division of the zygote divides the embryo into the future right and left halves of the butterfly, propose a hypothesis that explains how nondisjunction during the first mitosis might have produced this unusual-looking butterfly.
Question is also in the picture.
Meiosis is characterized by the pairing of homologouschromosomes during prophase I. In many species, an elaboratestructure called the synaptonemal complex forms betweenhomologues. During this pairing, homologues may exchangechromosomal material at sites called chiasmata. In meiosis I, thehomologues separate from each other, reducing the chromosomenumber to the haploid state (thus the reductive division). It isfollowed by a second division without replication, during whichsister chromatids become separated. The result of meiosis I and IIis four haploid cells.
If sister chromatids separated at the first division, would meiosis still work?
During metaphase I of meiosis, tetrads align along the metaphase plate independently of each other. Therefore, there is a random “shuffle” of maternal and paternal chromosomes in the resulting gametes.The following diagram demonstrates how this works in a diploid cell with four chromosomes . Because there are two pairs of chromosomes and each pair can align in one of two ways during metaphase I, the number of possible variations in the gametes produced is , or .For an organism that is , there are three pairs of chromosomes, so the number of possible variations in the gametes produced due to independent assortment in metaphase I is , or .
In an organism with a haploid number of , how many possible combinations of maternal and paternal chromosomes can occur in its gametes?
Select one:
a. 72=49
b. 27=128
c.17=1
d. 214=16 384
Chapter 3 Solutions
GENETIC ANALYSIS: AN INTEG. APP. W/MAS
Ch. 3 - Examine the following diagrams of cells from an...Ch. 3 - Our closest primate relative, the chimpanzee, has...Ch. 3 -
3. In a test of his chromosome theory of...Ch. 3 - Cohesion between sister chromatids, as well as...Ch. 3 - 5. The diploid number of the hypothetical animal...Ch. 3 - 6. An organism has alleles R1 and R2 on one pair...Ch. 3 - Explain how the behavior of homologous chromosomes...Ch. 3 - 8. Suppose crossover occurs between the homologous...Ch. 3 -
9. Alleles A and a are on one pair of autosomes,...Ch. 3 - Prob. 10P
Ch. 3 - Describe the role of the following structures or...Ch. 3 - A womans father has ornithine transcarbamylase...Ch. 3 - In humans, hemophilia A (OMIM 306700) is an...Ch. 3 -
14. A wild-type male and a wild-type female...Ch. 3 - 15. A woman with severe discoloration of her tooth...Ch. 3 - 16. In a large metropolitan hospital, cells from...Ch. 3 - In cats, tortoiseshell coat color appears in...Ch. 3 - 18. The gene causing Coffin–Lowry syndrome (OMIM...Ch. 3 - 19. Four eye-color mutants in Drosophila—apricot,...Ch. 3 - 20. For each pedigree shown,
a. Identify which...Ch. 3 - 21. Use the blank pedigrees provided to depict...Ch. 3 - 22. Figure 3.22 (page 89) illustrates reciprocal...Ch. 3 - 23. In fruit flies, yellow body (y) is recessive...Ch. 3 - 24. In a species of fish, a black spot on the...Ch. 3 - LeschNyhan syndrome (OMIM 300322) is a rare...Ch. 3 - 26. In humans, SRY is located near a...Ch. 3 - 27. In an 1889 book titled Natural Inheritance...Ch. 3 - 30. Drosophila has a diploid chromosome number of...Ch. 3 - 29. A wild-type Drosophila male and female are...Ch. 3 - 28. In Drosophila, the X-linked echinus eye...Ch. 3 - 31. While examining a young tortoiseshell cat, you...Ch. 3 - 32. Redgreen color blindness in humans is...
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