Mitosis refers to the process in which cells divide, resulting in two daughter cells that are identical to the parent cell. Though not usually necessary, mitosis occurs when cells grow to such a large size that their organelles and structures begin to overlap and interfere with each other's function. Mitosis is responsible for producing all of the cells in an organism's body, and it can be observed in onion root tips.
Introduction to the study
Mitosis is a process that can be observed in all plant and animal cells, including onion root tips. It involves sequential replication of chromosomes, followed by separation of each daughter nucleus into two identical daughter cells. Mitosis requires a large number of biochemical events that occur in a precise order, and take place within specific cell structures known as mitotic spindles. Scientists continue to conduct research on mitosis; one reason is because it helps scientists understand how cancer cells reproduce unchecked.
Why Onion Roots:
Onion roots are an excellent example of root meristem activity. The root tips of onion contains meristematic cells which are commonly known as Dividing cells. The onion root tip is also commonly used for studies about mitosis, because it is easy to see mitotic figures (cells dividing) in young root tips. All tissues above ground in an onion plant are derived from cells that were once located in the onion’s tip. That includes flowers, leaves, and small bulbs which later develop into large ones. Therefore, what we observe here in terms of cell division represents not only some key features in human biology but also aspects of plant development. It is one thing to read about mitosis as a concept and quite another thing to actually be able to witness it under a microscope or other instrumentation.
Materials and Methods
You will need a sharp razor blade, a piece of Packing material, and some really sharp scissors. First, cut a row through each tip of the root hairs to form many rows. Line the division in your packing material block with the appropriate divisions on your paper with your scissors. Now cut mitotic figures through the center of each cell division with your scissors. The mitotic figures should be at least three cells long, but don’t have to go all of the way from one side of the petri dish to another. Observe these slides every day for 24 hours or until you see anaphase. This may take one or two days, depending on how much time it takes for karyokinesis to occur. Make drawings and sketches of each stage so that you can observe and record any important findings during your dissection process.
Conclusion
The onion root tip has two stages of cell division, prophase and metaphase. Prophase is when nuclear envelope breaks down allowing chromosomes to move towards equator of cell. Metaphase occurs once all chromosomes have aligned at equator, prior to moving to opposite poles during anaphase. Finally, during telophase all nuclear material reassembles back into a single nucleus and so begins cytokinesis which then creates two daughter cells.
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