A male Drosophila from a wild-type stock is discovered to have only seven chromosomes, whereas normally 2n = 8. Close examination reveals that one member of chromosome IV (the smallest chromosome) is attached to (translocated to) the distal end of chromosome II and is missing its centromere, thus accounting for the reduction in chromosome number. (a) Diagram all members of chromosomes II and IV during synapsis in meiosis I.

A male Drosophila from a wild-type stock is discovered to have only seven chromosomes, whereas normally 2n = 8. Close examination reveals that one member of chromosome IV (the smallest chromosome) is attached to (translocated to) the distal end of chromosome II and is missing its centromere, thus accounting for the reduction in chromosome number. (a) Diagram all members of chromosomes II and IV during synapsis in meiosis I.

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter2: Cells And Cell Division

Section: Chapter Questions

Problem 25QP: We are following the progress of human chromosome 1 during meiosis. At the end of prophase I, how...

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We are following the progress of human chromosome 1 during meiosis. At the end of prophase I, how many chromosomes, chromatids, and centromeres are present to ensure that chromosome 1 faithfully traverses meiosis?
Variations in Chromosome NumberAneuploidy Describe the process of nondisjunction and explain when it takes place during cell division.
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?
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.
Two phenotypically normal parents produce a phenotypicallyabnormal child in which chromosome 5 is missing part of its longarm but has a piece of chromosome 7 attached to it. The child alsohas one normal copy of chromosome 5 and two normal copies ofchromosome 7. With regard to chromosomes 5 and 7, what do youthink are the chromosomal compositions of the parents?
In Neurospora, his2 mutants require the amino acidhistidine for growth, and lys4 mutants require theamino acid lysine. The two genes are on the samearm of the same chromosome, in the ordercentromere - his2 - lys4.A his2 mutant is mated with a lys4 mutant. Draw all ofthe possible ordered asci that could result from meioses in which the following events occurred, accountingfor the nutritional requirements for each ascospore.Ascospores without any copy of a chromosome willabort and die, turning white in the process.a. A single crossover between the centromere and his2b. A single crossover between his2 and lys4c. Nondisjunction during the first meiotic divisiond. Nondisjunction during the second meiotic divisione. A single crossover between the centromere andhis2, followed by nondisjunction during the firstmeiotic divisionf. A single crossover between his2 and lys4,followed by nondisjunction during the firstmeiotic division
The human genome consists of 23 pairs of chro-mosomes (22 pairs of autosomes and one pair of sex chro-mosomes). During meiosis, the maternal and paternal setsof homologs pair, and then are separated into gametes, sothat each contains 23 chromosomes. If you assume thatthe chromosomes in the paired homologs are randomlyassorted to daughter cells, how many potential combina-tions of paternal and maternal homologs can be gener-ated during meiosis? (For the purposes of this calculation,assume that no recombination occurs.)
For each of the following types of chromosomalaberrations, tell: (i) whether the chromosomes of anorganism heterozygous for the aberration will formany type of loop during prophase I of meiosis;(ii) whether a chromosomal bridge can be formedduring anaphase I in a heterozygote, and if so, underwhat conditions; (iii) whether an acentric fragmentcan be formed during anaphase I in a heterozygote,and if so, under what conditions; (iv) whether theaberration can suppress meiotic recombination; and(v) whether the two chromosomal breaks responsible for the aberration occur on the same side or on opposite sides of a single centromere, or if the two breaksoccur on different chromosomes.a. Reciprocal translocationb. Paracentric inversionc. Small tandem duplicationd. Robertsonian translocatione. Pericentric inversionf. Large deletion
A woman with an abnormally long chromosome 13 (and a normalhomolog of chromosome 13) has children with a man with anabnormally short chromosome 11 (and a normal homolog of chromosome 11). What is the probability of producing an offspringthat will have both a long chromosome 13 and a short chromosome11? If such a child is produced, what is the probability that thischild will eventually pass both abnormal chromosomes to one ofhis or her offspring?
The kidney bean plant, Phaseolus vulgaris, is a diploid speciescontaining a total of 22 chromosomes in somatic cells. Howmany possible types of trisomic individuals could be producedin this species?
Rice has a chromosome number of 2n = 24. If different aneuploids are available in rice, identifythe specific aneuploidy that shows the following chromosomal configurations at diakinesis ormetaphase I. Also provide the formula and chromosome number of the different aneuploids. Complete the table. Chromosome configuration at diakinesis or metaphase I Specific Type of Aneuploidy Formula (e.g. 2n+1) Chromosome number (2n=24) Types of gametes n, n+1, n+2, n-1, n-2) a. 1 III + 11 II b. 1 IV + 11 II c. 1 I + 11 II d. 11 II e. 2 I + 10 II
I. In humans, chromosome 16 sometimes has a heavilystained area in the long arm near the centromere. Thisfeature can be seen through the microscope but has noeffect on the phenotype of the person carrying it.When such a “blob” exists on a particular copy ofchromosome 16, it is a constant feature of that chromosome and is inherited.A couple conceived a child, but the fetus hadmultiple abnormalities and was miscarried. When thechromosomes of the fetus were studied, it was discovered that it had three copies of chromosome 16 (it wastrisomic for chromosome 16), and that two of thethree chromosome 16s had large blobs. Bothchromosome 16 homologs in the mother lacked blobs,but the father was heterozygous for blobs. Which parent experienced nondisjunction, and in which meioticdivision did it occur?