Essentials of Genetics (9th Edition) - Standalone book
9th Edition
ISBN: 9780134047799
Author: William S. Klug, Michael R. Cummings, Charlotte A. Spencer, Michael A. Palladino
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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Students have asked these similar questions
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]
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?
Alleles of genes A and B were analyzed in Neurospora according to the cross shown below. Ordered tetrads are summarized in each horizontal row with the number of tetrads in each category listed alongside.
A) Analyze the data to determine the recombination frequency (RF) between A and B, along with any additional information that is available from this data.
B) Draw a map of the chromosome or chromosomes with appropriate map distances.
C) Use the Perkins formula to reanalyze any relationship between A and B.
Chapter 6 Solutions
Essentials of Genetics (9th Edition) - Standalone book
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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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- 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.arrow_forwarda) 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 distances.arrow_forwardTwo 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_forward
- 7.7 Genes a and b are 20 cM apart. An a* b*la* b* individual was mated with an a bla b individual. (a) Diagram the cross and show the gametes produced by each parent and the genotype of the F₁. (b) What gametes can the F, produce, and in what proportions? (c) If the F, was crossed to a bla b individuals, what off- spring would be expected, and in what proportions? (d) Is this an example of the coupling or repulsion link- age phase? (e) If the F, were intercrossed, what offspring would be expected, and in what proportions?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_forwardShown below is a pedigree for Phenylketonuria (PKU), an autosomal recessive metabolic disorder. The characteristic feature of PKU is severe mental retardation A) What is the probability that individual II-1 is heterozygous for this gene? B) What is the probability that individual III-4 is heterozygous for this gene? C) If individuals III-3 and III-4 were to marry, what is the probability that their child would express PKU?arrow_forward
- In 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_forwardRice has a chromosome number of 2n = 24. If different euploids and aneuploids are available in rice, identify the chromosomal mutation, chromosome configuration, chromosome number, and/or type of gametes in each of the mutations below. Example: For 10B, the answer is “10 II + 2 I”arrow_forward
- Please 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_forwardA PORTION OF THE LINKAGE MAP OF CHROMOSOME 2 IN THE TOMATO IS ILLUSTRATED HERE. ci (compound influorescence) o (oblate) - 15 CM 20 CM p (peach) THE OBLATE PHENOTYPE IS A FLATTENED FRUIT, THE PEACH PHENOTYPE IS HAIRY FRUIT (LIKE A PEACH), AND COMPOUND INFLORESCENCE MEANS CLUSTERED FLOWERS. IGNORE THE PEACH LOCUS. AMONG 1000 GAMETES PRODUCED BY A PLANT OF GENOTYPE O CI /+ +, WHAT TYPES OF GAMETES WOULD BE EXPECTED, AND WHAT NUMBER WOULD BE EXPECTED OF EACH?arrow_forwardProgeny 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_forward
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