2. ( Of all the chromosomal disorders, abnormalities in chromosome number are the most easily identifiable from a karyotype (chromosome smear). While most of the time, meiosis occurs "correctly", occasionally pairs of homologous chromosomes fail to separate during meiosis. This is called nondisjunction. The risk of nondisjunction increases with the age of the parents. Nondisjunction can occur at meiosis I or meiosis II 1. For a diploid cell with n= two chromosomes (so the cell has 2n=4 chromosomes), draw pictures, label the stages, and explain the outcome if nondisjunction occurs at meiosis I or meiosis II. 2. In each case, indicate the percent of gametes that have the normal complement of chromosomes, one extra, and one too few. 3. Give an example of a disease or syndrome that is the result of nondisjunction. Indicate the chromosome involved.

2. ( Of all the chromosomal disorders, abnormalities in chromosome number are the most easily identifiable from a karyotype (chromosome smear). While most of the time, meiosis occurs "correctly", occasionally pairs of homologous chromosomes fail to separate during meiosis. This is called nondisjunction. The risk of nondisjunction increases with the age of the parents. Nondisjunction can occur at meiosis I or meiosis II 1. For a diploid cell with n= two chromosomes (so the cell has 2n=4 chromosomes), draw pictures, label the stages, and explain the outcome if nondisjunction occurs at meiosis I or meiosis II. 2. In each case, indicate the percent of gametes that have the normal complement of chromosomes, one extra, and one too few. 3. Give an example of a disease or syndrome that is the result of nondisjunction. Indicate the chromosome involved.

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Description: 2.Of all the chromosomal disorders, abnormalities in chromosome number are the most easily identifiablefrom a karyotype (chromosome smear). While most of the time, meiosis occurs "correctly", occasionally pairs ofhomologous chromosomes fail to separ

Biology 2e

2nd Edition

ISBN:9781947172517

Author:Matthew Douglas, Jung Choi, Mary Ann Clark

Publisher:Matthew Douglas, Jung Choi, Mary Ann Clark

Chapter13: Modern Understandings Of Inheritance

Section: Chapter Questions

Problem 3VCQ: Figure 13.6 Which of the following statements about nondisjunction is true? Nondisjunction only...

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Figure 13.6 Which of the following statements about nondisjunction is true? Nondisjunction only results in gametes with n+1 or n-1 chromosomes. Nondisjunction occurring during meiosis II results in 50 percent normal gametes. Nondisjunction during meiosis I results in 50 percent normal gametes. Nondisjunction always results in four different kinds of gametes.
Assuming that independent assortment occurs during meiosis, what type(s) of gametes will form in individuals with the following genotypes? a. AABB b. AaBB c. Aabb d. AaBb
Assuming that independent assortment occurs during meiosis, what type(s) of gametes will form in individuals with the following genotypes? a. AABB b. AaBB c. Aabb d. AaBb
8. Down Syndrome most commonly results from having three copies (trisomy) of chromosome 21 instead of two. Below is a fertilization event that could have given rise to Down Syndrome. Identify samete is abnormal and explain how the abnormal gamete could have been produced from a hondisjunction event in meiosis I and from a nondisjunction event in meiosis i.
1.What happens during anaphase in mitosis, meiosis I, and meiosis II? What happens if the steps you just described do not occur correctly during meiosis? State the term for this sort of meiotic error and the term that describes the resulting daughter cells.
1. A diploid organism has the genotype I1I2V1V2 Y1Y2 on different chromosomes. Diagram only these three pairs of chromosomes to represent: Any correct mitotic phase, label the alleles. Any correct meiotic phase, label the alleles. Compare the results of mitosis with the results of meiosis in terms of the number of chromosomes and the genotype of the cells produced.
A. 1. Division of the cell nucleus, results in two daughter nuclei, each have the same number of chromosomes as the parent nucleus. 2. One two identical halves of a duplicated chromosome. 3. Fusion of haploid (n) gametes; results in the formation of a diploid (2)n zygote. 4. The breaking and rejoining of homologous (non sister) chromatids during early meiotic prophase I, resulting in an exchange of genetic material. 5. The diploid (2n) cell that results from the union of haploid (n) gametes in sexual reproduction. 6. The condition of having one set of chromosomes per nucleus. 7. The complex of DNA, proteins and some RNA that makes up eukaryotic chromosomes. 8. Structures in the cell nucleus, composed of chromatin and containing the genes. 9. An X-shaped site in a tetrad marking the location where homologous chromatids previously underwent crossing over. 10. A sex cell; in plants and animals, an egg or sperm. 11. Type of reproduction in which two gametes (usually, but not necessarily,…
. If you were asked to complete the table with the correct answer, which of the following table would you chose? А. CHITERIA MITOSIS MEIOSIS 1. Na. of nuciear dimsion 2. Syriapaia/crossing over ECentromere of suster chromatids atanaphase Preseut separates Fresent M-attached/M-separates Haploid S. Na of chromosomes per daughter cell 6 Function Diplaid Growth. Rapair Growth. Repair and Reproduction B. CRITERIA MITOSIS MEIOSIS TNo, af nuclear darinion Synapsin/croing over 3. Centromere af sister chromatids at anaphase Absetit sepiarates Fresent -attached FNo. of daughter cells 5. No. of chromosomes per daughter cell 6 Function Diploid Haploid Growth, Eapair Growth, Repair and Reproduction C. CRITERIA MITOSIS MEIOSIS 1. No. of muclear division 2. Synapsis/crossing over 3. Centromereof sister chromatids at anaphane 4 Na, af daughter cells 5. No. of chromosoetes per daughter cell 6 Punction Absent Present separates MI-attached/Mli-separates Haploid Diploid Gruwth, Repair Reproduction D.…
2. There are two pairs of chromosomes in a diploid cell (2n=4). Label the genes and alleles on homologs and sister chromatids. A is on the big chromosome and B is on the smaller chromosome. The genotype is AaBb. Using a vertical metaphase plate, draw the two independent orientations of this AaBb cell in Metaphase I of MEIOSIS. OR GAMETES:
3) For each cell below, identify the meiosis phase (meiosis I or II) and stage of meiosis it is in (or if it is in interphase).
. Four of the following events are part of both meiosis andmitosis, but only one is meiotic. Which one? (1) Chromatidformation, (2) spindle formation, (3) chromosome condensation, (4) chromosome movement to poles, (5)synapsis.
3. Put the following images in the order they are most likely to occur during meiosis: A H