An amoeba is an important, single-celled organism found in freshwater. These microscopic protozoans are an omnivore which mostly feeds on both plants and animals. They mostly feed on diatoms, algae, microscopic organisms and other dead organic matter present in water. The mode of nutrition in amoeba is Holozoic. Nutrition in an amoeba occurs through a process called phagocytosis where the entire organism pretty much engulfs the food it plans on eating up. As amoeba is a unicellular organism, it does not have any specialized organ for the mechanism of nutrition. Its entire process is carried through the body surface with the help of pseudopodia.
Let us have a clear picture of the different processes involved in the nutrition of amoeba
The image below summarizes the stepwise process through which nutrition in amoeba occurs.
Mechanism of Nutrition
The different processes involved in the nutrition of amoeba are:
Ingestion is the process of taking in the food into the body either by swallowing or absorbing it. Amoeba takes in its food through this process. Initially, when the amoeba sense some food nearby they move toward it, pushes out its pseudopodia and encircle the food. After it engulfs the food, forms a bag-like structure called food vacuole and this process is known as “phagocytosis”.
Digestion is the process of breaking the insoluble and large food molecules into soluble and minute molecules. In amoeba, the food vacuoles are transported deeper into the cell and with the help of the digestive enzymes, the large insoluble foodstuffs are consequently broken down to the simple soluble molecules.
In this process of absorption, the nutrients from the digested food material are absorbed into the cell’s cytoplasm by leaving behind the undigested food material through the wall of the food vacuole. This process is named diffusion. The excess food is stored in the in the form of glycogen and lipids.
Assimilation is the process of obtaining energy from the absorbed food molecules. In amoeba, the absorbed food is utilized for energy production for its growth, repair as well as for multiplication.
Egestion is the process of removing the undigested food material from the food vacuole of the cell. In amoeba, these process is carried on by rupturing the cell membrane to remove the undigested food material from its body.
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