MBG 2040 Study Guide - Midterm Guide: Sister Chromatids, Zygosity, Y Chromosome

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lilacduck832

27 Nov 2015

School

University of Guelph

Department

Molecular Biology and Genetics

Course

MBG 2040

Professor

Jim Uniacke

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Document Summary

Use this information to answer the next two questions. Bivalents are segregated from each other during meiosis i, so none are left at meiosis ii. Immediately before s phase of the cell cycle, there would be 24 chromosomes in a tomato leaf cell. The organism is 2n=24, so 24 chromosomes in a cell before division: above statement is true, above statement is false. An xxy human has a banana with an xo drosophila on it. A students says the human and fly are males and the banana is an autotriploid. Y in humans dictates the male sex, one x in drosophila dictates the male sex, and bananas can be autotriploid: the student is correct, the student is incorrect. Rex coats in rabbits is controlled by a single gene, r. rabbits with at least one dominant allele, r, have normal coats. Homozygous recessive, r r, rabbits have rex coats (wavy, velvet-like coats).

Related Questions

Nonsister chromatids:

a. are attached at the centromere

b. both come from the father

c. are segregated randomly at meiosis I

d. come from both the maternal and paternal genomes

e. none of the above

(I know crossing over for nonsister chromatids occur duringmeiosis I...)

Telomeres are specialized repetative DNA sequences found at theends of chromosomes. How many telomeres are present in ahuman cell at prophase I of meiosis?

a. 23

b. 46

c. 92

d. 184

e. 368

A human cell has 23 chromosomes with 46 chromosome. In whichphase of meiosis is it?

a. telophase II

b. metaphase I

c. prophase II

d. prophase I

e. all but c

A triploid cell contains 3 sets of chromosomes. If acell of a usually diploid species with 42 chromosomes per cell istriploid, this cell would be expected to have which of thefollowing?

a. 63 chromosomes on 31 1/2 pairs

b. 63 chromosomes in 21 sets of 3

c. 63 chromosomes, each with three chromatids

d. 21 chromosome pairs and 21 unique chromosomes

(I'm leaning toward b, but I'm not sure)

blackmallard517

While working in a pathology lab, you are presented with an ovine blood sample (2n=54) that is suspected to have a genetic abnormality. You decide to karyotype the sample and diagnose trisomy 24.

1. Assume two hypothetical genes A and B are located on chromosomes 24 and 25 respectively. How many alleles for each gene will be present in the Primary oocyte, secondary oocyte and ovum that produced the animal with the abnormal karyotype indicated above â Provide answers for all possible scenarios.

2. Describe the number of autosomal chromosomes and chromatids in the Primary oocyte, Secondary oocyte and ovum that produced the animal with the abnormal karyotype indicated above â Provide answers for all possible scenarios

3. Another two hypothetical genes P and Q are located on chromosome 1; with the dominant alleles (P and Q) in coupling phase, and recessive alleles (p and q) in coupling phase on homologous chromosomes. Suppose a single crossing over occurs between the two genes during meiosis. What is the probability that the ovum that gave rise to karyotypically abnormal animal contains a chromatid with dominant alleles P and Q in coupling phase?

4. Suppose the animal had an XXY karyotype instead of trisomy 24. Did non-disjunction occur in the male or female parent (or both) and at which division(s), meiosis I or meiosis II?

While working in a pathology lab, you are presented with a bovine blood sample (2n=60) that is suspected to have a genetic abnormality. You decide to karyotype the sample and diagnose trisomy 29. Assume two hypothetical genes A and B are located on chromosomes 28 and 29 respectively. How many alleles for each gene will be present in the Primary oocyte, secondary oocyte and ovum that produced the animal with the abnormal karyotype indicated above â Provide answers for all possible scenarios. (1.5 marks) Describe the number of chromosomes and chromatids in the Primary oocyte, Secondary oocyte and ovum that produced the animal with the abnormal karyotype indicated above â Provide answers for all possible scenarios. (1.5 marks) Another two hypothetical genes P and Q are located on chromosome 1; with the dominant alleles (P and Q) in repulsion phase, and recessive alleles (p and q) in repulsion phase on homologous chromosomes. Suppose a single crossing over occurs between the two genes during meiosis. What is the probability that the ovum that gave rise to karyotypically abnormal animal contains the dominant or recessive alleles in coupling phase? (1 mark) Suppose the animal had an XXY karyotype instead of trisomy 29. Did non-disjunction occur in the male or female parent (or both) and at which division(s), meiosis I or meiosis II? (1 mark)

MBG 2040 Study Guide - Midterm Guide: Sister Chromatids, Zygosity, Y Chromosome

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