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Anatomy and Physiology. Cellular Division The Cell Cycle: Mitosis. The Cell Cycle. The series of changes that a cell undergoes from the time it forms until the time it divides. Interphase.
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Anatomy and Physiology Cellular Division The Cell Cycle: Mitosis
The Cell Cycle • The series of changes that a cell undergoes from the time it forms until the time it divides.
Interphase Period between cell divisions when a cell is carrying on its normal functions and is preparing for division. • Stages of Interphase • G1 - Growth phase - cells grow and develop, rapid growth and protein synthesis. • S - Synthesis phase - DNA replication occurs. • G2 - Growth phase - centrioles replicate, cell prepares for cell division.
Mitosis • Division of a somatic cell to form two genetically identical nuclei. • P.M.A.T • Prophase • Metaphase • Anaphase • Telophase
Mitosis • Somatic Cells - body cells, chromosome number is constant. • Chromosomes exist in pairs. • Ex. We have 23 pairs of chromosomes or 46 chromosomes. • Called diploid or 2N (two homologous copies of a chromosome) • Each pair of chromosomes carries the genetic information for the same trait - Homologous.
Chromosome Structure • Sister Chromatids • Duplicated chromosome made in S phase of interphase. • Centromere • Holds sister chromatids together.
4 Stages of Mitosis: Prophase • Chromatin in the nucleus condenses to form visible chromosomes. • Nuclear membrane breaks down. • Nucleolus disappears. • Centrioles move to opposite sides of the cell. • Microtubules form spindle fibers attached to centrioles.
4 Stages of Mitosis: Metaphase Chromosomes align in the center of the cells and attach to the spindle fibers by their centromeres.
4 Stages of Mitosis: Anaphase • Centromeres separate- sister chromatids move to opposite ends (poles) of the cell. • The individual sister chromatids are now call individual chromosomes.
4 Stages of Mitosis: Telophase • Like prophase in reverse. • Chromosomes uncoil. • Nuclear membrane reforms around chromosome set. • Nucleoli become visible inside nucleus again. • Spindle fibers break down.
Cytokinesis: Cytoplasmic Division • Considered a separate stage. • Cell membrane pinches in on itself until 2 daughter cells are formed. Cytokinesis
Cell Differentiation • The process by which cells develop different structures and specialized functions. • Controlled by the activation of certain genes.
Stem Cells • A precursor cell that can be triggered by genes to become any type of cell.
Meiosis - Formation of Gametes • Meiosis only occurs during the production of gametes. • After fertilization, the diploid zygote divides by mitosis producing a multicellular, diploid organism.
Meiosis • Meiosis reduces the chromosome number from diploid to haploid. • Occurs in two divisions, called meiosis I and meiosis II. • Divisions result in 4 daughter cells, each with half the number of chromosomes as the parent. • Meiosis 1 separates the homologous chromosomes (2 copies of each chromosome-1 from mom & 1 from dad) and Meiosis 2 separates sister chromatids.
