Stages of the Cell Cycle Divided into 2 main stages Interphase- G1, S, G2 Mitotic Phase- M

Stages of the Cell Cycle G1 phase- growth S phase- “synthesis”, chromosomes copied G2 phase- cell completes preparations for cell division Mitosis- division of cells to 2 daughter cells

The Stages of Mitosis Prophase Chromosomes condense and nuclear membrane disappears Each chromosome appears as a sister chromatid- X SHAPE FORMATION Mitotic spindle, consisting of microtubules and other proteins, forms between the two pairs of centrioles as they migrate to opposite poles of the cell. THIS IS USED TO PULL THE CHROMOSOMES APART

The Stages of Mitosis Prometaphase Breakdown of nuclear envelope into small fragments Microtubules interact with the chromosomes Bundles of microtubules extend from each pole toward the middle Each of the 2 chromatids has a specialized structure called a kinetochore. Some microtubules attach to the kinetochore to begin movement Kinetochore

The Stages of Mitosis Metaphase Centrosomes are now at opposite poles of the cell Chromosomes convene on the metaphase plate-immaginary line between poles Centromeres aligned and the kinetochores of the sister chromatids are attached to microtubules coming from opposite poles of the cell The microtubules are called spindles b/c of their shape

The Stages of Mitosis Anaphase Paired centromeres of each chromosome separate, freeing sister chromatids Each chromatid is considered a full fledged chromosome The once joined sisters begin to move towards opposite poles of the cell By the end of anaphase, the 2 poles of the cells have equivalent and a complete collections of chromosomes

The Stages of Mitosis Telophase Nonkinetochore microtubules elongate the cell, and daughter nuclei form at the poles of the cell Nuclear envelopes arise from the fragments of the parent cell’s nuclear envelope Chromatin fiber becomes less tightly coiled CYTOKINESIS- division of cytoplasm takes place shortly after end of mitosis

Cytokinesis Cleavage furrow forms which pinches the cell into 2 parts, near the old metaphase plate. On the cytoplasmic side of the furrow is a contractile ring of microfilaments which contracts to pull apart the cells like a drawstring Finally 2 separate cells are created