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Asexual Reproduction aka MITOSIS!. In asexual reproduction, cell division results in 2 identical “ daughter ” cells being produced from a “parent” parent cell Each human cell has 46 chromosomes in its nucleus. Cell Cycle - Mitosis. 10% of cell life cycle The cell undergoes cell division.
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Asexual Reproduction aka MITOSIS! • In asexual reproduction, cell division results in 2 identical “daughter” cells being produced from a “parent” parent cell • Each human cell has 46 chromosomes in its nucleus
Cell Cycle - Mitosis • 10% of cell life cycle • The cell undergoes cell division In humans, millions of cells divide every second to maintain a total of ~60 trillion cells - some divide once a day (skin & hair), others less often (stomach lining) and some not at all (nerve & muscle cells)
Stages of Mitosis Mitosis is a continual process, but we divide it into 4 phases Mitosis phases: • Prophase • Metaphase • Anaphase • Telophase
Mitosis 1. Prophase • chromatin condenses into distinct duplicated chromosomes • Nuclear membrane begins to disintegrate • In animal cells organelles called the centrioles move to opposite sides of the cell (“poles”) • Astral rays (microtubles) form around centrioles
Be sure to label: • Sister chromatids/ chromosomes • Centrioles • Astral rays • Nuclear memebrane Draw a prophase diagram Centrioles Astral Rays Made of 2 sister chromatids, attached by a centromere Nuclear membrane disintegrates
Mitosis Step 2: Metaphase • Chromosomes line up at equatorial plate and centromere attaches to spindle fibers that formed from elongated astral rays • At the end of this phase the centromere splits separating the sister chromatids • Nuclear membrane disappears
Draw a diagram • Be sure to label: • Centromere • Equatorial plate • Spindle fibers • Centriole Spindle Fibres Centrioles Centromere Equatorial Plate
Mitosis Step 3: Anaphase • The spindle fibers contract, pulling the chromosomes (sister chromatids) to the opposite poles of the cell • Centromeres divide
Draw a diagram • Be sure to include: • Sister chromatids • Spindle fibres • Centromere • Centrioles Centrioles Centromere is split
Mitosis Step 4: Telophase • Chromatids reach opposite poles; spindle and astral rays disappear • Chromosomes unwind back into chromatin • Nuclear membrane begins to reform • Cell membrane pinches in the middle to divide the cell = Cytokinesis
Cytokinesis • Cytoplasm begins to divide by forming a cleavage furrow at the equator and pinches off • Forming 2 daughter cells, with genetic information identical to each other • These cells will become the new parent cells • Cytokinesis in an animal cell Cleavage furrow
Draw a diagram • Be sure to liable: Part A: • Cleavage furrow • Nuclear membrane Part B: • Daughter cells • Nuclear membrane • Chromatin Daughter cells Chromatin Nuclear membrane
INTERPHASE PROPHASE
METAPHASE ANAPHASE TELOPHASE & CYTOKINESIS Metaphase plate Cleavagefurrow Nucleolusforming Nuclearenvelopeforming Daughterchromosomes Spindle
Metaphase Interphase Prophase Metaphase Anaphase Telophase
Animals Versus Plants • There are 2 main differences in plant cell division • Plants do not contain centrioles • They contain microtubules that create many of the same proteins (spindles), they just don’t have the centrioles 2. Plants do not undergo cytokinesis - Instead a cell plate forms at the equator of the cell to form a new cell wall
Cytokinesis • Animal Cytokinesis Plant Cytokinesis Cleavage furrow Cell Plate