Meiosis

Chapter 13  · Homologous Chromosomes/ Homologues  - Chromosome that have the same length, and centromere position  - Carry genes controlling the same inherited characters  · Haploid Cells  - Cell with a single chromosome set  - Abbreviated //n// (//n//=23)  · Fertilization  - Union of haploid gametes to produce diploid zygote <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Zygote <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Contains 2 haploid sets, bearing genes from the maternal & paternal family lines <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Tetrads <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - 4 complex chromatids <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Diploid Cells <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Zygote and all other cells having two sets of chromosomes <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Abbreviated //2n (2n=46)// <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Meiosis <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - 2-stage type of cell division in sexually reproducing organisms that results in gametes with half the chromosome # of the original cell <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Interphase I <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Each of the chromosomes replicate <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 85.5pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> § Results in 2 genetically identical sister chromatids <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Prophase I <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Chromosomes begin to condense <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Homologous chromosomes, made of 2 sister chromatids come together as pairs <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Chromatids of homologues are criss-crossed <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Chiasmata <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 85.5pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> § Homologues that have exchanged genetic material through criss crossing <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Centrosomes move away from each other <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Microtubules capture the kinetochores that form on the chromosomes <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Metaphase I <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Chromosomes now arranged on the metaphase plate à still in homologous form <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Anaphase I <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Sister chromatids move as a single unit toward the same pole <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - The homologous chromosome moves toward the opposite pole <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Telophase I / Cytokinesis <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Spindle apparatus continue to separate the homologue pairs until they reach the poles of the cell <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Each pole has a haploid chromosome set, but each chromosome has 2 sister chromatids <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - In Telophase I, the cell might be preparing for the 2nd meiotic division prior to meiosis II <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Prophase II  <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Spindle fibers form <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Metaphase II <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Chromosomes are positioned on the metaphase plate <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Anaphase II <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Centrosomes of sister chromatids finally separate <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Individual chromosomes move toward opposite poles of the cell <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Telophase II / Cytokinesis <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Nuclei form at opposite poles of the cell <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - End of Cytokinesis <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 85.5pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> § 4 daughter cells <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 103.5pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> 9 With 23 chromosomes <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"> (Page 230 Top Picture) <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Fertilized Egg to Adult à Mitosis <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Diploid <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">**<span style="font-family: Symbol; font-size: 10pt; line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;">· **Egg or Sperm (unfertilized) à Meiosis <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Haploid <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 27pt; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> · Random Fertilization due to: <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Independent assortment of homologous chromosomes during Meiosis I <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Crossing over between homologous chromosomes during Prophase I  <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - Random Fertilization of an ovum (egg) by a sperm <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="line-height: normal; margin-bottom: 0in; margin-left: 0.75in; margin-right: 0in; margin-top: 0in; text-indent: -9pt;"> - 2 parents will produce a zygote with about 64 trillion diploid combinations