The Cell Cycle & Cell Division
Cells have a life cycle Cells develop and grow Somatic cells (body cells) of a multicellular organism perform specialized functions to keep the organism functioning Life cycle of a cell is called the Cell Cycle Interphase Mitosis
The Cell Cycle
The Cell Cycle The sequence of growth and division of a cell. ~95% of cell cycle in interphase Time when cell carries out its function ~5% of cell cycle in mitosis Cell divides
Interphase The cell prepares for division Cell carries out its “life” functions Maintains homeostasis and carries out metabolic reactions DNA replicated Organelles replicated Cell increases in size
Chromosomes Homologous Chromosomes Sister chromatids Centromere Pair of chromosomes that have the same types of genes on them in the same locations Sister chromatids A duplicated chromosome Created after DNA replication Centromere Holds sister chromatids together after DNA replication
Chromosomes Before replication = 2 copies of each chromosome (homologous pair) After replication = 4 copies of each chromosome (sister chromatids within a homologous pair)
Cell Division: Mitosis Cells leave interphase and enter mitosis to… Maintain size Growth and repair Asexual reproduce (unicellular organisms)
Mitosis can be divided into stages Prophase Metaphase Anaphase Telophase Cytokinesis
Prophase The cell prepares for nuclear division DNA condenses into chromosomes Nuclear membrane disappears
Metaphase Chromosomes line up on the metaphase plate Chromosomes line up at the center of the cell Spindle fibers attach to the chromosomes at the centromere
Anaphase The chromosomes divide and separate Spindle fibers pull chromosomes apart by separating the sister chromatids of each homologous pair
Telophase The Nuclei Return Chromosomes begin to uncoil Nuclear membranes begin to form
Cytokinesis The cytoplasm divides Cytoplasm divides and separates Cleavage furrow pinches cell membrane between the two new nuclei Happens at the same time as telophase 2 identical daughter cells are formed