Allium amplectens (pink form of this western American onion) Allium przewalskianum (an Asian species) Allium schoenoprasum 'Snowcap' , a dwarf white-flowered chive Allium heldreichii (a hardy species from Greece)

Investigating Mitosis in Allium Root Tip

4 Phases of Mitosis Prophase Metaphase Anaphase Telophase and Cytokinesis

Interphase (Pre-Mitosis) Cell prepares for division by: A cell being a cell growing, functioning, replicating DNA and organelles. THIS IS NOT MITOSIS…pre-phase -DNA is replicated -Cells size is slightly increasing

Prophase Cell prepares for nuclear division by: Coiling chromatin into chromosomes Digesting nuclear membrane Creating spindle fibers -DNA is condensed into chromosomes -Nuclear envelope disappears (Nuclear envelope is a membrane system that surrounds the nucleus of eukaryotic cells. It separates the contents of the nucleus (DNA in particular) from the cytosol. )

Metaphase Cell prepares chromosomes for division by: aligning chromosomes at cell equator attaching spindle fibers to sister chromatids of each chromosome -Chromosomes align at the equatorial plate -Spindle fibers begin to move to a pole

Anaphase Chromosomes divide: Spindle fibers pull chromosomes apart. Separated chromatids move to opposite ends of the cell. -Sister Chromatids separate -Centromeres divide

Telophase/Cytokinesis Cytoplasm divides: Chromosomes uncoil (revert to chromatin), two new nuclear membranes form, ell plate forms to create two daughter cells. -Chromatin expands -A new cell wall sperates the 2 newly formed cells -Cytoplasm divides in Cytokinesis

Can you identify the mitosis phases in these cells?  Explore Allium root with a microscope. Where was the most growth in this tissue? Try to find cells in mitosis. Can you identify the stage of mitosis for one or more cells?

Parts of the Onion Root Review parts of root: Region of Maturation- where root hairs develop and cells differentiate -------------------------------------> Region of Elongation- area in which growth occurs Apical Meristem- region containing the highest percentage of cells undergoing mitosis ------------------------------------> Root Cap- functions in protection --------------------------------------> Review parts of root: -Maturation: root hairs develop & cells differentiate -Elongation: growth occurs here -Meristem: cell division/mitosis occurs here -Root Cap: protection

Which mitosis phase requires the most time Which mitosis phase requires the most time? Which mitosis phase requires the least time? How can we know? Why does it matter? MITOSIS PHASE Number of Cells found in that phase Percent of total mitotic cells counted Prophase Metaphase Anaphase Telophase Review parts of root: -Maturation: root hairs develop & cells differentiate -Elongation: growth occurs here -Meristem: cell division/mitosis occurs here -Root Cap: protection