2.3 Meiosis This process is more complicated than what occurs in mitosis. In meiosis, the genetic complement is cut in half so that the daughter cells each have half the number of chromosomes as the original cell. Because of this, meiosis is often called a reduction division. The genetic complement is now half the original, meaning one copy of each chromosome pair ends up in each daughter cell. This is the haploid number. This process produces the gametes, the sperm, and the ovum, and it takes place in the testes and ovaries, respectively. Two divisions, meiosis I and meiosis II, make this possible. Prior to meiosis, the chromosomes replicate themselves, again becoming double stranded. Thus, there are 46 double-stranded chromosomes when meiosis I begins. During meiosis I, the homologous chromosomes pair with each other, join together, and intertwine. The homologous chromosome pairs separate, with one homologue moving into one daughter cell, while the other homologue moves into the second daughter cell. The end result of meiosis I is two daughter cells with 23 double-stranded chromosomes each. In meiosis II, each daughter cell now divides, resulting in four daughter cells total. In the nucleus, the sister chromatids separate, with one strand going into each daughter cell. The result is four daughter cells, each with half the number of original chromosomes (23). In males, this process is referred to as spermatogenesis and produces four sperm cells. In females, this process is called oogenesis and produces one egg cell and three polar bodies; the polar bodies later disintegrate. When an egg and sperm combine, the resulting zygote has one set of 23 chromosomes from the mother and one set of 23 chromosomes from the father. EXERCISE 2: Mitosis and Meiosis Compare and contrast mitosis and meiosis in the human with the following matching questions. produces somatic cells produces 4 daughter cells as final product begins with 46 chromosomes produces 2 daughter cells as final product one cell division one chromosome replication produces gametes daughter cells have 23 chromosomes each two cell divisions daughter cells are diploid A. mitosis B. meiosis C. both mitosis and meiosis

2.3 Meiosis This process is more complicated than what occurs in mitosis. In meiosis, the genetic complement is cut in half so that the daughter cells each have half the number of chromosomes as the original cell. Because of this, meiosis is often called a reduction division. The genetic complement is now half the original, meaning one copy of each chromosome pair ends up in each daughter cell. This is the haploid number. This process produces the gametes, the sperm, and the ovum, and it takes place in the testes and ovaries, respectively. Two divisions, meiosis I and meiosis II, make this possible. Prior to meiosis, the chromosomes replicate themselves, again becoming double stranded. Thus, there are 46 double-stranded chromosomes when meiosis I begins. During meiosis I, the homologous chromosomes pair with each other, join together, and intertwine. The homologous chromosome pairs separate, with one homologue moving into one daughter cell, while the other homologue moves into the second daughter cell. The end result of meiosis I is two daughter cells with 23 double-stranded chromosomes each. In meiosis II, each daughter cell now divides, resulting in four daughter cells total. In the nucleus, the sister chromatids separate, with one strand going into each daughter cell. The result is four daughter cells, each with half the number of original chromosomes (23). In males, this process is referred to as spermatogenesis and produces four sperm cells. In females, this process is called oogenesis and produces one egg cell and three polar bodies; the polar bodies later disintegrate. When an egg and sperm combine, the resulting zygote has one set of 23 chromosomes from the mother and one set of 23 chromosomes from the father. EXERCISE 2: Mitosis and Meiosis Compare and contrast mitosis and meiosis in the human with the following matching questions. produces somatic cells produces 4 daughter cells as final product begins with 46 chromosomes produces 2 daughter cells as final product one cell division one chromosome replication produces gametes daughter cells have 23 chromosomes each two cell divisions daughter cells are diploid A. mitosis B. meiosis C. both mitosis and meiosis

Biology Today and Tomorrow without Physiology (MindTap Course List)

5th Edition

ISBN:9781305117396

Author:Cecie Starr, Christine Evers, Lisa Starr

Publisher:Cecie Starr, Christine Evers, Lisa Starr

Chapter8: How Cells Reproduce

Section: Chapter Questions

Problem 2.1DID

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