Mitosis in Allium Root Tips
- The tip of the onion of the plant genus allium is a favorite for studying mitosis.Jupiterimages/Photos.com/Getty Images
Mitosis, or division, is the process by which chromosomes split within growing plant cells. The cells produced by the split contain the genetic characteristics of the original cell. The apical meristems, or the growing tips of allium, the onion genius, have large chromosomes, and they stain darkly, making them a favorite for viewing the process of mitosis in the laboratory. Mitosis is sometimes divided into five stages, beginning with interphase; some texts list four stages, beginning with prophase. - Interphase, involving the first and final stages of dividing plant cells, is the state in which a cell grows larger, reproducing its DNA. The cell is preparing to divide, and its nucleus may be seen clearly under a microscope.
Joseph C. Rossi, a student at the Rochester Institute of Technology, photographed five stages of the mitosis of allium root tip through a compound light microscope, beginning with the interphase, and has made them available online in clear images. - During prophase, the chromosomes in the cell begin to coil up in the center of the cell, and the envelope containing the nucleus beings to break down. The website Microscope has drawings that clearly illustrate prophase, metaphase, anaphase and telophase.
- During metaphase, the middle stage of mitosis, pairs of chromosomes line up in the cell nucleus on spindles of fibers that pull to the sides of the cell.
- During anaphase, the spindle fibers attached to the sides of the cell shorten; as the spindle fibers grow shorter, they separate the pairs of chromosomes, pulling them to opposite sides of the cell.
- In telophase, the final stage of mitosis, the pairs of chromosomes break apart. Cell walls form around the separated chromosomes, forming identical daughter cells. Each daughter cell begins the interphase, growing and replicating its chromosomes as it prepares to divide again.
