Mitosis PP

MITOR DIVISION

What is Mitosis?

  • Mitosis is a cell's process for making copies of itself.

  • It occurs when:

    • The cell needs to grow.

    • The cell needs to repair itself.

    • The cell needs to replace old or damaged cells.

  • Preparation:

    • The cell ensures it has everything necessary to divide into two new cells.

Stages of Mitosis

  • The stages include:

    • Interphase

    • Prophase

    • Metaphase

    • Anaphase

    • Telophase

    • Cytokinesis

Interphase

  • Interphase occurs before mitosis begins and is crucial for cell division:

    • The cell grows in size.

    • DNA is duplicated.

    • Preparations for division are made.

  • Note: Interphase is not considered part of mitosis, but it is essential as a precursor.

Prophase

  • The official beginning of mitosis:

    • Chromatin condenses into visible chromosomes.

    • Each chromosome consists of two identical sister chromatids joined at a centromere.

    • Breakdown of the nuclear envelope occurs.

    • Spindle fibers start to form.

Metaphase

  • Characterized by the alignment of chromosomes:

    • Chromosomes line up along the metaphase plate, equidistant from the poles.

    • This alignment ensures equal distribution of chromosomes to daughter cells.

Anaphase

  • Defined by sister chromatid separation:

    • Spindle fibers attached to centromeres shorten.

    • Sister chromatids are pulled apart to opposite poles of the cell.

Telophase

  • Occurs after chromatids have reached the poles:

    • New nuclear envelopes form around separated chromosomes.

    • Chromosomes decondense back into chromatin.

    • Spindle fibers disassemble.

Cytokinesis

  • The final stage of cell division:

    • The cytoplasm of the parent cell divides into two daughter cells.

    • In animal cells, a cleavage furrow forms, pinching the cell membrane inward.

Conclusion

  • After cytokinesis, daughter cells re-enter interphase, restarting the cycle:

    • Each daughter cell is genetically identical to the parent cell.

    • Both daughter cells contain the same number of chromosomes.

  • Mitosis is vital for:

    • Growth

    • Development

    • Tissue repair

    • Asexual reproduction in multicellular organisms.