Mitosis is nuclear division; cytokinesis is cell division. In the lab students should learn to recognize cells in interphase and in any of the four stages of mitosis. Further, students should relate what they learn in lecture to their observations in lab as outlined below. Students are to determine the relative duration of each stage of mitosis by their pooled observations.
The Cell Cycle:
Go to a Slide Show of Each Stage of Mitosis
Interphase: The non dividing cell: Includes three stages, G1, S, and G2 described in lecture. The cell's chromosomes are dispersed as chromatin inside the nucleus.
Link to view of interphase cell.
Link to view of interphase cell of Narcissus root tip squash
Link to E.M. of interphase Cell
The Stages of Mitosis:
Prophase: The chromatin becomes condensed and the chromosomes become visible. Each chromosome consists of two chromatids. This stage ends with the breakdown of the nuclear envelope.
Link to view of prophase cell of Allium (onion) root tip
Link to view of prophase cell of Narcissus root tip squash
Metaphase: A network of microtubules form called the spindle. Individual microtubules connect to each chromosome at the centromere. These rearrange the chromosomes so that they line-up along the cell equator.
Link to view of metaphase cell of Allium (onion) root tip
Link to view of metaphase cell of Narcissus root tip squash
Anaphase: Chromatids separate and become the chromosomes of daughter nuclei. These are pulled to opposite ends of the cell.
Link to view of anaphase cell of Allium (onion) root tip
Link to view of anaphase cell of Narcissus root tip squash
Telophase: Begins when the chromosomes stop moving. During this stage the chromosomes disperse to form chromatin and the nuclear envelope reforms. Telophase in most plant cells is coupled with cytokinesis. Cell division is accomplished through the formation of a cell plate. This action is facilitated by a system of microtubules called the phragmoplast which directs the movement of vesicles formed by dictyosomes.These vesicles deliver pectic materials to the forming cell plate. The membranes of the vesicles coalesce to form a continuous new membrane that will divide the mother cell in two.
Link to view of telophase cell of Allium (onion) root tip
Link to view of telophase cell of Narcissus root tip squash
Link to E.M. of telophase cell showing developing cell plate
Duration of Stages of Mitosis - Link to Frequency Counts This Semester
Link to frequency counts from Narcissus from Fall, 2017
Link to frequency counts from Allium from Fall, 2013
Link to frequency counts from Narcissus from Spring, 2013
Link to frequency counts from Allium from Fall, 2012