Mitosis and Meiosis

Mitosis

Stages of Mitosis:

• Prophase
  • Duplicated Membranes coil and become visible
  • Nuclear Membrane dissapears
  • Centrioles Divide and move to opposite poles
  • Spindle Fibres form
• Metaphase
  • Chromosomes line up along the middle of the cell
  • Spindle fibres attach to each chromatid of each chromosome
• Anaphase
  • Sister Chromatids move to the opposite ends of the spindle
  • The spindle fibres pull apart the structures, and are now called sister chromosomes
• Telophase
  • The separated chromosomes group together at the end of the cell
  • A new nuclear membrane forms, and the chromosomes start to become chromatids
  • Animal Cells pinch in, Plant Cells start to grow new cell membranes and walls
  • Each daughter cell will have the exact copy of the original DNA, and half of each molecule will be from the parent cell
• Cytokinesis occurs: The cytoplasm is split into two different cells (Not part of mitosis)

Meiosis

• Production/Formation of Germ Cells
• Basis of Sexual Reproduction
• Only germ, and sex cells undergo meiosis

Interphase: A pair of homologous chromosomes duplicate into sister chromatids

Crossing Over: Exchange of Genetic Material between Non-Sister Chromatids of Homologous Chromosomes during meiosis, which results in new and different combinations of the daughter cells

Example of Crossing Over