cell divsion

• Interphase: The first phase of the cell cycle, during which the cell grows and copies its DNA (parent cell to new copy). Chromosomes condense and thicken until they are visible. 90% interphase and 10% mitosis or meiosis.
• Prophase: Chromosomes thicken or condense and become visible.

  • Cell membrane disassembles
  • Nuclear membrane disintegrates
  • Centrioles divide and move to poles
  • Mitotic spindle begins to form between centrioles

  In meiosis however, 2 pairs of chromosomes (1 from mom and 1 from dad) pair together if homologous and have a process called ‘crossover’ where they swap a gene and the dominant trait is expressed in the child.
• Metaphase: In this third stage of mitosis, chromosomes line up along the middle of the cell and spindle fibres attach to them in mitosis. In meiosis, 2 pairs of chromosomes line up instead of one
• Anaphase: The chromosomes are pulled apart into sister chromatids in mitosis and same in meiosis yet the 2 chromosomes are pulled apart.

  • Centromeres divide
  • Sister chromatids begin moving towards the centromeres while being pulled by the spindle fibers
• Telophase: Chromosomes reach the opposite poles of the cell and divide into 2 cells in mitosis and 4 in meiosis. Chromosomes reach the opposite poles of the cell

  • The nuclear membrane forms
  • The nucleolus reappears
  • Chromosomes begin decondensing and become invisible
  • Cytokinesis happens (division of cytoplasm)
• Mitosis is the asexual reproduction of somatic cells to create an identical copy. It produces 2 daughter cells that are haploids (n) and is a simple process. Meiosis is sexual reproduction that produces germ cells in non-identical copies. It produces 4 daughter cells that are diploids (2n) and is a complex process.

  
• During meiosis, the number of chromosomes halves from 2n to n. During mitosis, the number of chromosomes stays at 2n.