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Objectives Name three parts of the cell cycle. Name four major parts of mitosis. Identify important parts of a dividing cell. Discuss important similarities and differences between mitosis and meiosis. The cell cycle has three major parts:. 1. Interphase. 2. Mitosis
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Objectives • Name three parts of the cell cycle. • Name four major parts of mitosis. • Identify important parts of a dividing cell. • Discuss important similarities and • differences between mitosis and meiosis.
The cell cycle has three major parts: 1. Interphase 2. Mitosis (Karyokinesis) (Mitosis has four major sub-parts) 1) Prophase 2) Metaphase 3) Anaphase 4) Telophase 3. Cytokinesis
Interphase • Characterized by: • Intact nuclear envelope • Visible nucleolus • Although you can’t tell it, • the cell’s DNA and other • cell components are undergoing a process called replication (duplication process); chromosomes become double-stranded. • 4. Three sub-phases: G1, S, and G2 Nuclear envelope Nucleolus
Mitosis = Karyokinesis Prophase • Characterized by: • Disappearing nuclear envelope • and nucleolus • Chromosomes (46* in each human cell) coil and condense • Spindle fibers (microtubules) • form and chromosomes become attached by way of centromeres • Newly formed centrioles • move to opposite ends of the cell *23 pairs of chromosomes Condensed chromosomes (chromatin fibers)
Mitosis = Karyokinesis Metaphase • Characterized by: • Chromosomes align across the • “equator” or metaphase plate • Centrioles stop at opposite • ends of the cell • Spindle apparatus is fully • formed Spindle apparatus Centrioles Metaphase plate Centrioles
Mitosis = Karyokinesis Anaphase • Characterized by: • Spindle fibers (microtubules) • shorten and separate the • chromosomes at the • metaphase plate • In the human cell, 46 single- • stranded chromosomes move • in opposite directions toward • each pole Centrioles Centrioles Shortening microtubules (spindle fibers)
Can you name structures in the dividing cell? single-stranded chromosome centromere centrioles spindle fiber (microtubule)
Mitosis = Karyokinesis Telophase • Characterized by: • Cleavage furrow forms • Nuclear envelopes begin to • form around two daughter • nuclei • Chromosomes decondense • Spindle disappears Cytokinesis (Division of cytoplasm and contents into two cells) cleavage furrow daughter nuclei
This figure represents an overview of meiosis (human female)
Similarities and Differences MITOSIS MEIOSIS