EBK GENETICS: FROM GENES TO GENOMES
5th Edition
ISBN: 8220100255250
Author: HARTWELL
Publisher: YUZU
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Chapter 12, Problem 43P
Chromosomes normally associate during meiosis I as bivalents (a pair of synapsed homologous chromosomes) because chromosome pairing involves the synapsis of the corresponding regions of two homologous chromosomes. However, Fig. 13.17b shows that in a heterozygote for a reciprocal translocation, chromosomes pair as quadrivalents (that is, four chromosomes are associated with each other). Quadrivalents can form in other ways: For example, in some autotetraploid species, chromosomes can pair as quadrivalents rather than as bivalents.
| a. | How could quadrivalents actually form in these autotetraploids, given that chromosomal regions synapse in pairs? To answer this question, diagram such a quadrivalent. |
| b. | How can these autotetraploid species generate euploid gametes if the chromosomes pair as quadrivalents rather than bivalents? |
| c. | Could quadrivalents form in an amphidiploid species? Discuss. |
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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 Xa. Draw the pairing arrangement of these chromosomes in prophase 1 of meiosis. Mention their gametic composition. b. Draw the alternate, adjacent I, and adjacent II segregation patterns in anaphase I of meiosis. Mention their gametic composition.
A diploid individual is heterozygous for a chromosome rearrangement. The original chromosome and its rearranged homolog have the following segments, where ∙ represents a centromere:
A B ∙ C D E F G
A B ∙ C F E D G
While paired in prophase I, a single crossing-over occurs between segment E and segment D of the paired chromosomes. Describe the unusual crossing-over structure that forms as a result.What gamete types will result from crossing over when meiosis is complete?
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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. Draw a picture of these chromosomes pairing in prophase I of meiosis.
Chapter 12 Solutions
EBK GENETICS: FROM GENES TO GENOMES
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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