Chapter 12 Mitosis - Chapter 12: The Cell Cycle (Mitosis)...

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Concept 12.1: Cell division results in genetically identical daughter cells Cellular Organization of the Genetic Material o Chromosomes: “colorful bodies;” sausage-shaped structures found when the cell is actively dividing. o Genome: cell’s total endowment of DNA o Chromatin: DNA associated with proteins o DNA are double-helix structures packed into chromosomes (DNA is packaged by wrapping around a protein and super-coiling) o Human body cells called somatic cells: contain 46 chromosomes made up of two sets of 23, one set inherited from each parent. ( we inherit 22 pairs of autosomes and 2 sex chromosomes) 46 is the diploid number 2n 23 is the haploid number n o To look at your chromosomes, take a blood sample and centrifuge the red blood cells out but keep the white blood cells (have nucleus). Place them in a hypotonic solution, and use a pipet to drop the cells in solution onto a slide. As they drop, they pop. Add cultusink to inhibit the mitotic spindle and then you will be able to see your chromosomes on the slide. Distribution of Chromosomes During Cell Division o When a cell is not dividing, and even as it duplicates its DNA in prep for cell division, each chromosome is in the form of a long, thin chromatin fiber. o When the cell is dividing, each duplicated chromosome has two sister chromatids . Each contains identical DNA and they are most closely attached at a specialized region called the centromere . o Homologues : have the same information but different forms (ex: short and tall: they are both info for height but are different forms of height)=====duplicated chromosomes are not homologous---they are sister chromatids. o Gene : certain parts of chromosome; responsible for proteins. o Mitosis : cells divide to form two new daughter cells The purpose of mitosis is growth and repair 1 cell creates two new cells that are exactly alike. o Cytokinesis : usually follows mitosis division of the cytoplasm. o Meiosis : occurs only in the gonads; yields nonidentical daughter cells that have only one set of chromosomes, thus half as many chromosomes as the parent cell---4 daughter cells with ½ the # of cells (go from diploid to haploid) Concept 12.2: The mitotic phase alternates with interphase in the cell cycle Phases of the Cell Cycle (Mitosis) o Interphase You cannot tell that anything is happening: see cell as it should appear A nuclear envelope bounds the nucleus and the nucleus contains a nucleolus Two centrosomes have formed by the replication of a single centrosome. In animal cells, each centrosome features two centrioles. Chromosomes duplicate and cannot be seen individually because they have not
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This note was uploaded on 04/30/2008 for the course BIO 123 taught by Professor Cusic during the Spring '08 term at University of Alabama at Birmingham.

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Chapter 12 Mitosis - Chapter 12: The Cell Cycle (Mitosis)...

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