Question

BIO 105 Laboratory Mitosis .Recognize and describe the phases of mitosis. o Be able to identify the phases of mitosis if shown models o Be able to identify the phases of mitosis if shown a slide (i.e. onion root tip or whitefish) o How would you identify interphase? Identify the fundamentals of cloning and its history Participate in deliberation using appropriate procedure. . Why deliberate? What did you learn by arguing a point, even if it was not your own? o o

Answer 1

The different phases of the mitosis or the M phase in a cell cycle is Prophase, Metaphase,Anaphase and telophase.

In order to identify the stages of Mitosis in Models; If by models the question means cell models then the phases on Mitosis can be identified as follows:

1. Prophase : The model shown contains condensed chromosomes, Mitotic spindle starts forming, the nucleus is gone.

2.Metaphase : The spindle fibres captures the condensed chromosomes by the formation of microtubules which get attached kinetochore( protein in the centromere) to each sister chromatids.

3. Anaphase : the model shows the sister chromatids pulled apart to the extreme ends by the microtubules.

4. Telophase: The model is characterised by decondensed chromosomes, nucleolus partially starts reappearing, the nuclear membrane reforms and the cell starts dividing(i.e a small cleavage sort of thing appears in the cell ).

In order to identify stages in Mitosis in slides:

Look for the chromosomes. If there are no chromosomes the cell is in interphase stage and the nucleus is in the process of duplicating the DNA.

Chromosomes appear as large,distinct dark objects. If chromosomes are present, they are X-shaped, the cell is in the first half of mitosis. This includes prophase, prometaphase and metaphase. Chromosomes as single dark lines present in the cell indicates the second half of mitosis. This includes anaphase and telophase.

If they are bunched together inside the nucleus, the cell is in prophase and the chromosomes have just been formed from the DNA.

If the X-shaped chromosomes are not inside a nucleus but not in a line and just loosely grouped inside the cell, the cell is in prometaphase. The nucleus has just broken down, and the chromosomes are beginning to move. If they are lined up across the middle of the cell, it is in metaphase and the chromosomes are preparing to divide.

If the chromosomes in the cell are line-shaped and they look like they are being pulled toward the ends of the cell by their centers, the cell is in anaphase.

If the chromosomes are bundled at the end of the cell is in telophase, and the new nuclei are in the process of formation. A new membrane begins to appear around each bundle. At the end of this phase the cell divides around the middle and divide into two. This process is called cytokinesis.