Onion root tips: structure and function

Onion Root Tips

Since a plant root is always looking for water and nutrients, it is in a continual state of growth and is ideal for studying cell division. The information presented in the table that follows shows the subjective cell cycle phases that an onion root tip undergoes. This particular cell spends more than half of the time in the first stage -- interphase, and in the following phase -- prophase the time spent is just over a quarter of the time, while the remaining two phases show a dramatic decrease in the total time.

Interphase

Prophase

Metaphase

Anaphase

Telophase

Total

number of cells percent of cells

Healthy cell division replaces old or dead cells and is a normal process of life. Meanwhile, unrestrained cell division is cancerous, which is responsible for more than 100 diseases that exhibit this characteristic. If a healthy cell's DNA becomes mutated whether by genetic makeup or through an introduction of say a carcinogen then regular cell division can malfunction. Once the cell mutates and if the remaining back up safety mechanisms fails, then cancer is more certain to develop. In order for cancer to take over the normal mechanism that controls the growth of the cell, proto-oncogene must fail. Along with this failure could be added the inability of the cell to repair its own DNA and to stop the process of the unhealthy cell growth that can in turn lead to developing tumors. Usually, the tumor suppressor, apoptosis, kicks in at this time to instruct the unhealthy cell to die. If this message is overridden and the cancerous cell manages to produce telomerase, it becomes immortal and continues with its runaway cell division. From this stage, often the cancer may be able to jump and spread (metastasis) to other areas in the body that it does not belong to bringing further complications that can lead to death. These days it has now been proven that a healthy lifestyle that includes a good diet and plenty of exercise can help to prevent cancer.