Concepts of Genetics (12th Edition)
12th Edition
ISBN: 9780134604718
Author: William S. Klug, Michael R. Cummings, Charlotte A. Spencer, Michael A. Palladino, Darrell Killian
Publisher: PEARSON
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Chapter 8, Problem 26ESP
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 symbol represent, and how many chromosomes would you expect to be present in t(14;21) Down syndrome individuals?
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In a human genetic study, a family with five phenotypicallynormal children was investigated. Two children were “homozygous”for a Robertsonian translocation between chromosomes19 and 20 (they contained two identical copies of the fusedchromosome). They have only 44 chromosomes but a completegenetic complement. Three of the children were “heterozygous”for the translocation and contained 45 chromosomes,with one translocated chromosome plus a normal copy of bothchromosomes 19 and 20. Two other pregnancies resulted instillbirths. It was later discovered that the parents were firstcousins. Based on this information, determine the chromosomecompositions of the parents. What led to the stillbirths? Whywas the discovery that the parents were first cousins a key pieceof information in understanding the genetics of this family?
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.
Consider the following two nonhomologous wildtype chromosomes, where letters or
numbers represent genes, the "-" represents the centromere of each chromosome, and
chromosomes are shown on separate lines.
ABCDE-FGHIJK
123-45678
Identify the type of rearrangement shown in each of the following (A-C) and then identify
whether it is balanced or unbalanced. Assume that the individual is diploid and
heterozygous for the rearrangement.
A.
ABCDE-FGHIJKGH
123-45678
Rearrangement:
[Select]
• Balanced or Unbalanced: [Select]
B.
ABCDGF-EHIJK
123-45678
Rearrangement: [Select]
Balanced or Unbalanced: [Select]
Chapter 8 Solutions
Concepts of Genetics (12th Edition)
Ch. 8 - A human female with Turner syndrome (47, X) also...Ch. 8 - When two plants belonging to the same genus but...Ch. 8 - What is the effect of a rare double crossover (a)...Ch. 8 - Controlling the overgrowth of invasive aquatic...Ch. 8 - Controlling the overgrowth of invasive aquatic...Ch. 8 - Controlling the overgrowth of invasive aquatic...Ch. 8 - HOW DO WE KNOW? In this chapter, we have focused...Ch. 8 - Review the Chapter Concepts list on page 171....Ch. 8 - Define these pairs of terms, and distinguish...Ch. 8 - For a species with a diploid number of 18,...
Ch. 8 - What evidence suggests that Down syndrome is more...Ch. 8 - What evidence indicates that humans with aneuploid...Ch. 8 - Contrast the fertility of an allotetraploid with...Ch. 8 - Describe the origin of cultivated American cotton.Ch. 8 - Predict how the synaptic configurations of...Ch. 8 - Inversions are said to suppress crossing over. Is...Ch. 8 - Contrast the genetic composition of gametes...Ch. 8 - Human adult hemoglobin is a tetramer containing...Ch. 8 - Discuss Ohnos hypothesis on the role of gene...Ch. 8 - What roles have inversions and translocations...Ch. 8 - The primrose, Primula kewensis, has 36 chromosomes...Ch. 8 - Certain varieties of chrysanthemums contain 18,...Ch. 8 - Drosophila may be monosomic for chromosome 4, yet...Ch. 8 - Mendelian ratios are modified in crosses involving...Ch. 8 - Having correctly established the F2 ratio in...Ch. 8 - The mutations called bobbed in Drosophila result...Ch. 8 - The outcome of a single crossover between...Ch. 8 - A couple planning their family are aware that...Ch. 8 - In a cross in Drosophila, a female heterozygous...Ch. 8 - A woman who sought genetic counseling is found to...Ch. 8 - Prob. 25ESPCh. 8 - In a recent cytogenetic study on 1021 cases of...Ch. 8 - A boy with Klinefelter syndrome (47,XXY) is born...Ch. 8 - Prob. 28ESPCh. 8 - A 3-year-old child exhibited some early indication...Ch. 8 - A normal female is discovered with 45 chromosomes,...
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- Two different female Drosophila were isolated, each heterozygous for the autosomally linked genes black body (b), dachs tarsus (d), and curved wings (c). These genes are in the order d–b–c, with b closer to d than to c. Shown in the following table is the genotypic arrangement for each female, along with the various gametes formed by both. Identify which categories are noncrossovers (NCO), single crossovers (SCO), and double crossovers (DCO) in each case. Then, indicate the relative frequency with which each will be produced.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_forwardPlease label the tetrad type in the table as PD (parental ditype), NPD (non parental ditype) or T (tetratype) and answer the following questions a) Are the genes linked? Please explain SPECIFICALLY how you can distinguish between linked and unlinked genes in this instance. b) If the two genes are linked, calculate the % recombination between ser and thr. Show the formula used, as well as all of your calculations. c) Draw a single map illustrating the arrangement of the two genes on the chromosome with respect to each other and to the centromere of the chromosome. Make sure to map ALL three distancesarrow_forward
- Progeny of triploid tomato plants often contain parts of an extra chromosome, in addition to the normal complement of 24 chromosomes (J. W. Lesley and M. M. Lesley. 1929. Genetics 14:321–336). Mutants with a part of an extra chromosome are referred to as secondaries. James and Margaret Lesley observed that secondaries arise from triploid (3 n), trisomic (3 n + 1), and double trisomic (3 n + 1 + 1) parents, but never from diploids (2 n). Give one or more possible reasons that secondaries arise from parents that have unpaired chromosomes but not from parents that are normal diploids.arrow_forwardIn the figure below, black and pink lines are used to represent nonhomologous chromosomes. Which of the figures matches the following descriptions? More than one diagram may correspond to any one statement, and a diagram may be a correct answer for more than one question. 1) Gametes produced by a reciprocal translocation heterozygote: 2) Genetically balanced gametes produced by a reciprocal translocation heterozygote:arrow_forwardConsider two hypothetical recessive autosomal genes a and b, where a heterozygote is testcrossed to a double- homozygous mutant. Predict the phenotypic ratios under the following conditions: (a) a and b are located on separate autosomes. (b) a and b are linked on the same autosome but are so far apart that a crossover always occurs between them. (c) a and b are linked on the same autosome but are so close together that a crossover almost never occurs.arrow_forward
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