ESSENTIALS OF GENETICS-MODIFIED ACCESS
9th Edition
ISBN: 9780134190006
Author: KLUG
Publisher: PEARSON
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Chapter 6, Problem 22PDQ
In a recent cytogenetic study on 1021 cases of Down syndrome, 46 were the result of translocations, the most frequent of which was symbolized as t(14;21). What does this designation represent, and how many chromosomes would you expect to be present in t(14;21) Down syndrome individuals?
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An individual is heterozygous for a reciprocal translocation, with the following chromosomes:
A • B C D E F
A • B C V W X
R ST • U D E F
R ST • U V W X
Q. Explain why the fertility of this individual is likely to be less than the fertility of an individual without a translocation.
In a diploid organism of 2n=10, assume that you can label all the centromeres derived from its female parent and all the centromeres derived from its male parent. When this organism produces gamestes, how many male and female-labeled centromere combinations are possible in the gametes?
. In a diploid organism of 2n = 10, assume that you canlabel all the centromeres derived from its female parentand all the centromeres derived from its male parent.When this organism produces gametes, how many maleand female-labeled centromere combinations are possible in the gametes?
Chapter 6 Solutions
ESSENTIALS OF GENETICS-MODIFIED ACCESS
Ch. 6 - CASE STUDY| Fish tales Aquatic vegetation...Ch. 6 - CASE STUDY |Fish tales Aquatic vegetation...Ch. 6 - CASE STUDY |Fish tales
Aquatic vegetation...Ch. 6 - HOW DO WE KNOW? In this chapter, we focused on...Ch. 6 -
CONCEPT QUESTION
2. Review the Chapter Concepts...Ch. 6 -
3. Define these pairs of terms, and distinguish...Ch. 6 -
4. For a species with a diploid number of 18,...Ch. 6 - What explanation has been proposed to explain why...Ch. 6 - Contrast the fertility of an allotetraploid with...Ch. 6 -
7. Why do human monosomies most often fail to...
Ch. 6 -
8. Describe the origin of cultivated American...Ch. 6 - Predict how the synaptic configurations of...Ch. 6 - Inversions are said to “suppress crossing over.”...Ch. 6 -
11. Predict the genetic composition of gametes...Ch. 6 - Human adult hemoglobin is a tetramer containing...Ch. 6 -
13. The primrose, Primula kewensis, has 36...Ch. 6 - Certain varieties of chrysanthemums contain 18,...Ch. 6 - Drosophila may be monosomic for chromosome 4, yet...Ch. 6 - Mendelian ratios are modified in crosses involving...Ch. 6 -
17. Having correctly established the F2 ratio in...Ch. 6 -
18. In a cross between two varieties of corn,...Ch. 6 -
19. A couple planning their family are aware that...Ch. 6 -
20. A woman who sought genetic counseling is...Ch. 6 - The woman in Problem 20 has had two miscarriages....Ch. 6 -
22. In a recent cytogenetic study on 1021 cases...Ch. 6 -
23. A boy with Klinefelter syndrome (47,XXY) is...Ch. 6 - In a human genetic study, a family with five...Ch. 6 - A 3-year-old child exhibited some early indication...Ch. 6 - A normal female is discovered with 45 chromosomes,...
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- Two phenotypically unaffected parents produce two children withfamilial Down syndrome. With regard to chromosomes 14 and 21,what are the chromosomal compositions of the parents?arrow_forwardAn individual has the following reciprocal translocation:What would be the outcome of alternate segregation and of adjacent-1segregation?arrow_forwardThree autosomal recessive mutations in yeast, all producing the same phenotype (m1, m2, and m3), are subjected to complementation analysis. Of the results shown below, which, if any, are alleles of one another? Predict the results of the cross that is not shown—that is, m2 * m3. Cross 1: m1 * m24 F1: all wild-type progeny Cross 2: m1 * m34 F1: all mutant progenyarrow_forward
- An individual heterozygous for a reciprocal translocation possesses the following chromosomes: A B • C D E F G A B • C D V W X R S • T U E F G R S • T U V W X Q. Give the products that result from alternate, adjacent-1, and adjacent-2 segregation.arrow_forwardThe mutant genes for vestigial wings and singed bristles are approximately 30 map units apart on chromosome II in Drosophila. Assume that a vestigial-winged female was mated to a singed-bristle male, and that the resulting F1 phenotypically wild type females were mated to vestigial singed males. Of 1000 offspring, which phenotype class would represent the product of crossing over between the genes, and how many would you expect? a) vestigial, 300 flies b) vestigial, 150 flies wild type, 300 flies d) singed, 150 flies e) vestigial, singed double mutants, 150 fliesarrow_forwardWhen a female melanotic fly is crossed with a normal male, the progeny are produced: 123 normal females, 125 melanotic females, and 124 normal males. In subsequent crosses between melanotic females and normal males, melanotic females are frequently obtained, but never any melanotic males. Provide a possible explanation for the inhertiacne of the melanotic mutation (Hint: The cross produces twice as many female progeny as male progeny)arrow_forward
- Two phenotypically unaffected parents produce two children with familial Down syndrome. Regarding chromosome 14 and 21, what are the chromosomal composition of the parents?arrow_forwardFemales of wild-type Strain A and males of mutant Strain B, as well as females of mutant Strain B and males of wild-type Strain A, make reciprocal crosses. Explain why reciprocal crosses are needed in genetics experiments involving Drosophila fruit flies.arrow_forwardAn individual is heterozygous for a reciprocal translocation, with the following chromosomes: A • B C D E F A • B C V W X R ST • U D E F R ST • U V W X Q. Draw the products of alternate, adjacent-1, and adjacent-2 segregations.arrow_forward
- On Neurospora chromosome 4, the leu3 gene is just to theleft of the centromere and always segregates at the firstdivision, whereas the cys2 gene is to the right of the centromere and shows a second-division segregation frequency of 16 percent. In a cross between a leu3 strain anda cys2 strain, calculate the predicted frequencies of thefollowing seven classes of linear tetrads where l = leu3 andc = cys2. (Ignore double and other multiple crossovers.)arrow_forwardIn a series of two-point mapping crosses involving five genes located on chromosome II in Drosophila, the following recombinant (single-crossover) frequencies were observed: pr–adp 29% pr–vg 13 pr–c 21 pr–b 6 adp–b 35 adp–c 8 adp–vg 16 vg–b 19 vg–c 8 c–b 27 (a) Given that the adp gene is near the end of chromosome II (locus 83), construct a map of these genes. (b) In another set of experiments, a sixth gene, d, was tested against b and pr: d–b 17% d–pr 23% Predict the results of two-point mapping between d and c, d and vg, and d and adp.arrow_forwardWhat is the probability of fixation of a unique new, neutralmutation in a population of N haploid individuals?arrow_forward
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