Onion Mitosis

Demo

My Demo that I have done here, is basically to show you how the onion cells go through a process called mitosis. In this experiment you'll learn how mitosis occurs and what happens when it does. .

What is Mitosis you might ask?

Well to break it down simply...

Mitosis is a process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It divides the nuclei, cytoplasm, organelles and cell membrane into two identical new cells. Mitosis and cytokinesis together define the mitotic (M) phase of the cell cycle—the division of the mother cell into two daughter cells. This accounts for approximately 10% of the cell cycle.

Mitosis occurs in five different stages and are shown here .Each one of these stages has a particular purpose. Each one of the stages are very important into identifying mitosis as a whole.

1.*Interphase

- DNA molecules of chromosomes (chromatin) replicating; chromosomes dispersed in nucleus as chromatin

A cell spends 90% of its time in the first three phases of the cycle; in which all of these stages are combined and called interphase.

The Phases include:

- G1 phase- a cell grows rapidly and carries out its routine functions
- Synthesis (S) phase- a cells DNA is copied during this phase.
- Second growth (G2) phase- preparations are made for the nucleus to divide.

Once the three phases are completed they move onto:

- Mitosis (M)- The process of cell division
- Cytokinesis- The process during cell division in which the cytoplasm divides.

2.*Prophase

-Chromatin condenses into chromosomes

3.*Metaphase

-Chromosomes line up on equator of cell; centromeres attach to spindle fibers; longtitudinal separation of chromatids (now chromosomes) occurs; chromatids remain joined at centromere.

4.*Anaphase

-Centromeres divide; each set of chromosomes moves toward an opposite end of the cell.

5.*Telophase

-Spindle fibers disappear; Chromosomes become diffuse; nuclear membrane and nucleolus reappear; cytokinesis (cytoplasmic division) occurs.

6.*Daughter Cells

- Mitosis and cytokinesis complete; two new cells in interphase result.

Materials needed for this project:

- preserved onion root tips
- 18% hydrochloric acid
- Carnoy fluid
- toluidine blue
- microscope slides
- coverslips
- 30 Student Guides
- paper towels or bibulous paper droppers razor blades or scalpels
- forceps

Procedures:

1. Obtain two small cups. Label one 2. Label the other "Carnoy" 3. Use forceps to transfer 4. After 4 minutes, transfer

"HCI" and pour enough HCI into it and pour enough Carnoy an onion root tip into the the root into the Carnoy fluid.

to cover the bottom. fluid in it to cover the bottom. cup of HCI. The root should remain in the

Carnoy fluid for 4 minutes.

After 4 minutes, place the root

on a slide.

5. With a razor blade or scalpel, 6. Cover the root tip with a 7. After 2 minutes, blot away 8. When the stain has been

cut off 1 to 2 mm of the root few drops of toluidine blue the stain (without touching blotted away, cover the

tip and discard all but this tip. for 2 minutes. the root tip). root tip with 1 or 2 drops

of water.

9. Gently lower a coverslip 10. Cover the slide with a piece 11. Observe your preparation

over the root tip. of towel or other absorb- under the low power of a

ent paper and firmly press microscope. If the cells

on the coverslip (w/o twisting are not sufficiently separated

it). The pressure will spread to permit viewing of each,

the cells into a single layer. squash the preparation again.

12. Using the low power of a microscope, search the slide to find cells in various stages of division. Once you have located a cell in division, change to high power. Try to observe several cells in each stage. Note the important features characteristic of each stage.

Thank You

If you have followed the procedures well you should get really good results. Thank you for taking time out to read about Onion Mitosis and how to accomplish this amazing expirement.

mitosis.docx