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Cell Division

Cell Division. Cell Cycle, Mitosis, and Cytokinesis. Chromosomes. Are bundled packages that contain genetic information (DNA). Must be copied before cell division begins. Make the process of separating DNA during cell division possible. Chromosomes. There are two types Prokaryotic

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Cell Division

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  1. CellDivision Cell Cycle, Mitosis, and Cytokinesis

  2. Chromosomes • Are bundled packages that contain genetic information (DNA). • Must be copied before cell division begins. • Make the process of separating DNA during cell division possible.

  3. Chromosomes • There are two types • Prokaryotic • Is a single, circular chromosome that contains almost all the cell’s genetic information.

  4. Chromosomes • Eukaryotic • Formation process • DNA and histones combine to form chromatin. • Chromatin coils tightly to form beadlike structures (nucleosomes). • Nucleosomes are packed together to form thick fibers. • Thick fibers form super coils which become chromosomes.

  5. Chromosomes

  6. The Cell Cycle • Is a series of events that cells go through as they grow and divide.

  7. The Cell Cycle • Prokaryotic cell cycle • Is known as binary fission • Includes a regular, and rapid, pattern of growth, DNA, replication, and cell division. • Produces two genetically identical cells.

  8. The Cell Cycle • Eukaryotic cell cycle • Consists of interphase and cell division. • Interphase is divided into three phases: Gap1 (G1), Synthesis (S), and Gap2 (G2). • Cell growth occurs during G1 phase. • New proteins and organelles are synthesized • DNA replication occurs during the synthesis (S) phase. • New DNA is synthesized whenchromosomes are replicated. • Cells have double the amount of DNA at the end of this phase.

  9. The Cell Cycle • Eukaryotic cell cycle • The cell is prepared for cell division during G2. • This is the shortest phase of interphase. • Organelles and molecules required forcell division are produced. • Cell division (M phase) includes mitosis and cytokinesis. • Occurs rapidly • In mitosis the cell nucleus is divided. • In cytokinesis the cytoplasm is divided.

  10. Mitosis • Is divided into four phases: prophase, metaphase, anaphase, and telophase.

  11. Mitosis • Prophase • Is the longest phase of mitosis. • Events • The genetic material inside the nucleus condenses. • Duplicated chromosomes become visible • Duplicated DNA strands are attached toa centromere. • Each DNA strand of the duplicatedchromosome is a chromatid.

  12. Mitosis • Metaphase • Is the shortest phase of mitosis • Events • The centromeres of the duplicated chromosomes line up across the center of the cell. • The spindle fibers connect the centromeres of each chromosome to the two poles of the spindle.

  13. Mitosis

  14. Mitosis • Anaphase • Events • The chromosomes separate from each other. • Chromosomes move to opposite ends of the cell. • Spindle fibers begin to break down.

  15. Mitosis

  16. Mitosis • Telophase • Events • Each cell has a complete set of chromosomes • Chromosomes become a tangle of chromatin. • A nuclear envelope forms around each new set of chromosomes. • The spindle fibers disappear.

  17. Mitosis

  18. Mitosis • Cytokinesis • Usually occurs at the same time as telophase. • Cells divide into new cells; each has its own nucleus. • Plant cells form a new cell wall in the center of the cell.

  19. Animal vs. Plant Cytokinesis

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