Onechromosome of a homologous pair carries thegenes J am K.The othen chromosome of the pair carries the genes j and kat corresponding loci. Crossing results in exchangeof chromosome segmentsand production of gametescombinations ofgenes. A "recombinautnewtypegameteresulfing from this cross oven might contain:A-Jaud KD-K and kB-J aud jE-j and Kand k

Crossing over is found in the prophase 1 of meiosis. It produces genetic variations.

One chromosome of a homologous pair carries the genes Jam K. The othen chromosome of the pair carrieo the genes jand k at corresponding loci. Crossing results in exchange of chromosome segmut of gamutes combinations of A "recombinaut and production with genes. new type gamete resulting from this cross over might contain: A-Jand K D-K and k B-J and j E-i and K and k

One chromosome of a homologous pair carries the genes Jam K. The othen chromosome of the pair carrieo the genes jand k at corresponding loci. Crossing results in exchange of chromosome segmut of gamutes combinations of A "recombinaut and production with genes. new type gamete resulting from this cross over might contain: A-Jand K D-K and k B-J and j E-i and K and k

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter6: Cytogenetics: Karyotypes And Chromosome Aberrations

Section: Chapter Questions

Problem 3QP: A colleague e-mails you saying that she has identified an interesting chromosome variation at 21q13....

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A normal female is discovered with 45 chromosomes, one ofwhich exhibits a Robertsonian translocation containing most ofchromosomes 18 and 21. Discuss the possible outcomes in heroffspring when her husband contains a normal karyotype.
in the experiment of following chromosomal dna mvement througgh meiosis, why. do you use non-sister chromatids to demobstrate crossing over? what combinatiobns of alleles could result from a crossover between BD and bd chromosomes? Identify two ways that meiosis contributes to genetic recombination. Why is it necessary to reduce the number of chromosomes in gametes, but not in other cell?
A male Drosophila from a wild-type stock is discovered to haveonly seven chromosomes, whereas normally 2n = 8. Closeexamination reveals that one member of chromosome IV (thesmallest chromosome) is attached to (translocated to) the distalend of chromosome II and is missing its centromere, thusaccounting for the reduction in chromosome number. (a) Diagram all members of chromosomes II and IV duringsynapsis in meiosis I.
. Chromosome 3 of corn carries three loci (b for plant-color booster, v for virescent, and lg for liguleless). A testcross of triple recessives with F1 plants heterozygous forthe three genes yields progeny having the followinggenotypes: 305 + v lg, 275 b + +, 128 b + lg, 112 + v +,74 + + lg, 66 b v +, 22 + + +, and 18 b v lg. Give the genesequence on the chromosome, the map distances between genes, and the coefficient of coincidence.
The normal sequence of nine genes on a certainDrosophila chromosome is 123 • 456789, where the dotrepresents the centromere. Some fruit flies were foundto have aberrant chromosomes with the followingstructures:a. 123 • 476589 c. 1654 • 32789b. 123 • 46789 d. 123 • 4566789Name each type of chromosomal rearrangement, anddraw diagrams to show how each would synapse withthe normal chromosome.
The karyotype of a young girl who is affected with familialDown syndrome revealed a total of 46 chromosomes. Her olderbrother, however, who is phenotypically unaffected, actually had45 chromosomes. Explain how this could happen. What wouldyou expect to be the numbers of chromosomes in the parents ofthese two children?
A couple planning their family are aware that through the pastthree generations on the husband’s side a substantial numberof stillbirths have occurred and several malformed babies wereborn who died early in childhood. The wife has studied geneticsand urges her husband to visit a genetic counseling clinic,where a complete karyotype-banding analysis is performed.Although the tests show that he has a normal complement of46 chromosomes, banding analysis reveals that one memberof the chromosome 1 pair (in group A) contains an inversioncovering 70 percent of its length. The homolog of chromosome1 and all other chromosomes show the normal bandingsequence. Question: How would you explain the high incidence of paststillbirths?
A couple planning their family are aware that through the pastthree generations on the husband’s side a substantial numberof stillbirths have occurred and several malformed babies wereborn who died early in childhood. The wife has studied geneticsand urges her husband to visit a genetic counseling clinic,where a complete karyotype-banding analysis is performed.Although the tests show that he has a normal complement of46 chromosomes, banding analysis reveals that one memberof the chromosome 1 pair (in group A) contains an inversioncovering 70 percent of its length. The homolog of chromosome1 and all other chromosomes show the normal bandingsequence. Question: What can you predict about the probability of abnormality/normality of their future children?
A woman who sought genetic counseling is found to be heterozygousfor a chromosomal rearrangement between the second andthird chromosomes. Her chromosomes, compared to those in anormal karyotype, are diagrammed on the next page:(a) What kind of chromosomal aberration is shown?
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