Every plant and animal carry chromosomes inside their eukaryotic cells. Mitosis is the process of the eukaryotic cell separating its chromosomes into two identical sets. The purpose of mitosis is for cell growth and replacement of old cells. Mitosis is important because they have a role of healing wounds or growing nails/height/hair etc. Also, germination of the seed is affected by mitosis. So without mitosis in human, plants and animals, they can become a serious issue.
Cell cycle allows cell division and replicate chromosomes to create chromatid, also known as daughter chromosome. Cell cycle is composed of 4 phases which are G1, S, G2 and Mitosis. G1, S and G2 are called interphase and during this time, cells prepare to divide and two identical sets of the chromosome are made inside the cell. This is when 90% of the cell cycle have already progressed. After interphase, mitosis starts to happen which is composed of 4 stages: prophase, metaphase, anaphase and telophase. Prophase is when the chromosomes start to condense. Metaphase is when cells align on the cell equator(middle of the cell). Anaphase is when the chromosomes get divided and chromatids are pulled to each side of the pole while the spindle helps to divide. Telophase is when two nuclei is made and the cell is ready to be divided. Finally, cytokinesis is when cytoplasm is divided, creating two identical baby cells with nuclear on each side.
Rapid rate of mitosis is very important because the abnormal growth of cell cause tumors. Cancer is a type of disease that happens when tumor happens in people’s body. Also when any error happens during the Mitosis, there will be a change in the cell’s DNA resulting in a genetic disorder. Mitosis can be affected by many different environmental factors such as mineral supply.
Sucrose is a common type of table sugar which is used in this lab and it is composed of glucose and fructose. Different sucrose concentration can manipulate the amount of protein in the cell which will have an effect on the mitosis of the plants as mitosis is the process of cell division which allows plants/animal/humans to grow or heal.
Inside the onion cells, there are chloroplasts, a type of organelles that contains chlorophyll which is a green pigment commonly found in plants. This pigment has a role of converting sunlight to energy during the photosynthesis. As onion includes most elements from plant cell structure, it is one of the best examples to represent the general plant cells while it is easy and fast to grow. It is also very easy to observe mitosis in onions as they are seen on the root.
In this experiment, different sucrose concentration will be applied on the same type of onions to find out how different concentration of sucrose can affect the mitosis of a plant.
How does different sucrose concentration on onion affect the growth of root?
If onion is grown in 7gm of sucrose concentration then it will have faster mitosis than 0gm of sucrose concentration because sucrose is a molecule that controls the genes during photosynthesis, metabolism and cell development process (mitosis). However, over high concentration of sucrose will slower the mitosis since sucrose is an important carbohydrate on plants and if over high concentration of sucrose is applied to the onions, this can cause genetic disorder in the onion cells which will eventually slow down the mitosis of an onion.
Sucrose Concentration (3 trials each)
? 3 gm
? 5 gm
? 7 gm
? 9 gm
Root length measured with ruler. (mm)
Number of root measured visually each day.
Amount of water used in every trial.
Environment of where the experiment is conducted
? Same location to ensure adequate sunlight
? Temperature of the room (+/- 5?)
Size of the onions
Volume of the cup
Do not proceed this experiment if you are allergic to onions or sugar.
Do not play with the screws
Screwing part may require parental guidance if you are young.