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The Cell Cycle

Explore the intricate world of the cell cycle, from chromosome replication to cell division stages like mitosis and cytokinesis. Understand the phases of interphase and mitosis. Discover why cells divide and how they ensure growth and repair through division.

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The Cell Cycle

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  1. The Cell Cycle

  2. Chromosomes • Before a cell can divide into two daughter cells, the chromosomes must replicate themselves • A duplicated chromosome is made of DNA, and is in the form of the letter “X” • The two halves of the “X” are referred to as sister chromatids, because they are copies of one another

  3. Cell Division • The centromere holds the “X” together

  4. The Cell Cycle • The cell cycle is a series of changes that a cell goes through from the time it is formed until it divides • The cell cycle is broken down into 2 main parts: Interphase and the Mitotic Phase

  5. The Cell Cycle

  6. Interphase • Interphase can be thought of as the “everyday life” of the cell where it performs all of its usual activities • Interphase is broken down into 3 phases; G1, S, and G2 • G1 - Stage of cell growth • S - DNA is copied (chromosome duplication) • G2 - Cell produces more organelles

  7. Mitotic Phase • During the mitotic phase, the cell divides its nucleus and its cytoplasm • Mitosis is the process of the division of the eukaryotic cell nucleus into two identical nuclei • Mitosis occurs in 4 stages A. Prophase B. Metaphase C. Anaphase D. Telophase • Cytokinesis, the division of the cytoplasm and organelles, occurs during and after telophase

  8. Cell Division • Why do cells divide? • Cells divide because they can not get too big (too big = difficult time obtaining enough resources!) • Cells divide so that an organism can grow, reproduce, and repair/replace old or damaged cells

  9. A closer look at Interphase Interphase • Cell grows and prepares for division • DNA has replicated, but has not yet formed into chromosomes

  10. A closer look at the Mitotic Phase Prophase • The DNA shortens and condenses to form chromosomes • The nuclear membrane and nucleolus are no longer visible • The centrioles move to the poles, and spindle fibers begin to form

  11. A closer look at the Mitotic Phase Metaphase • The chromosomes line up along the equatorial line of the cell. • Spindle fibers attach themselves to the centromeres of each chromosome

  12. A closer look at the Mitotic Phase Anaphase • The spindle fibers shorten and the centromere splits • The sister chromatids are pulled apart towards the centrioles

  13. A closer look at the Mitotic Phase Telophase • The chromosomes reach the poles of their respective spindles • Nuclear membranes form • The spindle fibers disintegrate

  14. A closer look at the Mitotic Phase Cytokinesis • Occurs during and after telophase, the cell is pinched in two and cytoplasm evens out so both cells are about equal size

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