Genetics: From Genes to Genomes, 5th edition
5th Edition
ISBN: 9780073525310
Author: Leland H. Hartwell, Michael L. Goldberg, Janice A. Fischer, Leroy Hood, Charles F. Aquadro
Publisher: McGraw-Hill Education
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Chapter 12, Problem 34P
The incidence of Down syndrome will be very high (somewhat less than 50%) among the offspring of a parent with Down syndrome. Diagram meiosis in the Down syndrome parent to explain why progeny have such a high risk for chromosome 21 aneuploidy. Explain in addition why the incidence of Down syndrome among these children might be less than 50%.
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Shown below are photomicrographs of Rhoeo tradescantia cells undergoing meiosis. Answer the following question for each of the photomicrographs:
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Explain how these aberrations are formed and relate to the possible causal mutation(s).
Will this result to sterile and/or fertile gametes? Explain.
The incidence of Down syndrome will be high (nearly 50%) among the offspring of a parent with Down syndrome. Diagram meiosis in the Down syndrome parent to explain why progeny have such a high risk for chromosome 21 aneuploidy. Explain in addition why the incidence of Down syndrome among these children might be less than 50%.
A diploid (2n) trihybrid individual with the genotype EeFfGg can make eight genetically different gametes.
Loci E/e and F/f are on chromosome 1 and locus G/g is on chromosome 2. Explain how a gamete containing the alleles e, f and g may be produced by meiosis. Refer specifically to meiotic events occurring during Prophase I, Metaphase I, Anaphase I and Anaphase II. (NB: remember to refer to the organism above).
Chapter 12 Solutions
Genetics: From Genes to Genomes, 5th edition
Ch. 12 - For each of the terms in the left column, choose...Ch. 12 - Prob. 2PCh. 12 - For each of the following types of chromosomal...Ch. 12 - For the following types of chromosomal...Ch. 12 - One of the X chromosomes in a particular...Ch. 12 - Prob. 6PCh. 12 - Prob. 7PCh. 12 - Prob. 8PCh. 12 - Two wild-type fragments of human genomic DNA from...Ch. 12 - Indicate which of the four major classes of...
Ch. 12 - The recessive, X-linked z1 mutation of the...Ch. 12 - Genes a and b are 21 m.u. apart when mapped in...Ch. 12 - In the following group of figures, the pink lines...Ch. 12 - Three strains of Drosophila Bravo, X-ray, and...Ch. 12 - Prob. 15PCh. 12 - Suppose a haploid yeast strain carrying two...Ch. 12 - In the mating between two haploid yeast strains...Ch. 12 - During ascus formation in Neurospora, any...Ch. 12 - In the following figure, black and pink lines...Ch. 12 - In Drosophila, the gene for cinnabar eye color is...Ch. 12 - Semisterility in corn, as seen by unfilled ears...Ch. 12 - Prob. 22PCh. 12 - Prob. 23PCh. 12 - Prob. 24PCh. 12 - Duchenne muscular dystrophy DMD is caused by a...Ch. 12 - Explain how transposable elements can cause the...Ch. 12 - The Drosophila genome normally harbors about 40 P...Ch. 12 - Prob. 28PCh. 12 - Fred and Mary have a child named Bob. The genomic...Ch. 12 - Uniparental disomy is a rare phenomenon in which...Ch. 12 - Among adults with Turner syndrome, it has been...Ch. 12 - In Neurospora, his2 mutants require the amino acid...Ch. 12 - Human geneticists interested in the effects of...Ch. 12 - The incidence of Down syndrome will be very high...Ch. 12 - The Drosophila chromosome 4 is extremely small;...Ch. 12 - Down syndrome is usually caused by having a...Ch. 12 - Common red clover, Trifolium pratense, is a...Ch. 12 - The numbers of chromosomes in the somatic cells of...Ch. 12 - Prob. 39PCh. 12 - Somatic cells in organisms of a particular diploid...Ch. 12 - Prob. 41PCh. 12 - Prob. 42PCh. 12 - Chromosomes normally associate during meiosis I as...Ch. 12 - Using whole-genome sequencing, how could you...Ch. 12 - Prob. 45PCh. 12 - Prob. 46PCh. 12 - Seedless watermelons that you find in the...Ch. 12 - Prob. 48PCh. 12 - What characteristic property of translocations...Ch. 12 - In examining the genome of the rice Oryza sativa...Ch. 12 - Prob. 51PCh. 12 - Prob. 52PCh. 12 - The accompanying figure shows idiograms of human...
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- Assume that a meiotic-nondisjunction event causes trisomy 8 in a newborn. If two of the three copies of chromosome 8 are absolutely identical, at what point during meiosis did the nondisjunction event take place?arrow_forwardHuman sex chromosomes are XX for females and XY for males. a. With respect to an X-linked gene, how many different types of gametes can a male produce? b. If a female is homozygous for an X-linked allele, how many different types of gametes can she produce with respect to this allele? c. If a female is heterozygous for an X-linked allele, how many different types of gametes can she produce with respect to this allele?arrow_forwardHuman females have two X chromosomes XX; males have one X and one Y chromosome XY. a. With respect to X-linked alleles, how many different types of gametes can a male produce? b. A female homozygous for an X-linked allele can produce how many types of gametes with respect to that allele? c. A female heterozygous for an X-linked allele can produce how many types of gametes with respect to that allele?arrow_forward
- A diploid (2n) trihybrid individual with the genotype AaBbDd can make eight genetically different gametes. 2n = 4 n = 2 (1) A d. ID 1 1 2 2 Gt: AaBbDd Loci A/a and D/d are on chromosome 1 and locus B/b is on chromosome 2. Explain how a gamete containing the alleles A, D and b may be produced by meiosis. Refer specifically to meiotic events occurring during Prophase I, Metaphase I, Anaphase I and Anaphase II. (NB: remember to refer to the organism above). COarrow_forwardBriefly illustrate how nondisjunction in meiosis can result in Down syndrome.arrow_forwardImagine a germ cell for an animal that is 2n=4. Gene A and B are found on chromosome one, and the cell is homozygous for A(AA) and heterozygous for Bb. Gene D is found on chromosome 2 and the germ cell is heterozygous for the Allee of the gene (Dd). Meiosis for this germ cell results in the following four gametes, and one crossing over event during meiosis ABD, ABd, AbD, Abd. Draw the chromosomes in cell during metaphase of meiosis 1. Make sure to include chromosomes, the allele in the correct locations on the chromosomes AFTER the crossing over event, and spindle fibers.arrow_forward
- if a species of animal has 18 chromosomes in its diploid cells (2n=18). Describe what the metaphase chromosome arrangement would look like for this species in each of the following stages: mitosis, meiosis I, and meiosis Ilarrow_forwardThough an individual with abberations such as Robertsonian translocation may be phenotypically normal, they can generate gametes through meiosis that have atypical organizations of chromosomes, resulting in recurrent fetal abnormalities or miscarriages. Why, despite these Robertsonian translocations, are affected cells still able to generate typical gametes through meiosis?arrow_forwardIn general, why do changes in chromosome structure or numbertend to affect an individual’s phenotype? Explain why somechanges in chromosome structure, such as reciprocal translocations,do not.arrow_forward
- Suppose you have a line of mice that has cytologicallydistinct forms of chromosome 4. The tip of the chromosome can have a knob (called 4K) or a satellite (4S) orneither (4). Here are sketches of the three types:4K4S4You cross a 4K/4S female with a 4/4 male and find thatmost of the progeny are 4K/4 or 4S/4, as expected.However, you occasionally find some rare types asfollows (all other chromosomes are normal):a. 4K/4K/4b. 4K/4S/4c. 4KExplain the rare types that you have found. Give, asprecisely as possible, the stages at which they originate,and state whether they originate in the male parent,the female parent, or the zygote. (Give brief reasons.)arrow_forwardAn 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. Diagram the alternate, adjacent-1, and adjacent-2 segregation patterns in anaphase I of meiosis.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 S T • U D E F R S T • U V W X a. Draw a picture of these chromosomes pairing in prophase I of meiosis. b. Draw the products of alternate, adjacent-1, and adjacent-2 segregations. c. Explain why the fertility of this individual is likely to be less than the fertility of an individual without a translocation.arrow_forward
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