The cytoplasm of the body cannot absorb directly the food materialswhich Amoeba intakes. Reacting with various enzymes these food materials are converted into simple components for assimilation. This is digestion process.
Digestion occurs in two process-acidic and alkaline. Amoeba has no digestive system. Food is digested inside the food vacuoles. Along with the body movements the food vacuoles are brought well inside the endoplasm. Inside. the endoplasm, hydrochloric acid from the inner membrane of the vacuoles works on the food. It kills the living food materials and makes the contents acidic. Thus the acidic process is finished. Next alkali is secreted from the neighboring cytoplasm which brings the partly digested food material into the alkali media. At this time, various types of enzymes are secreted from the endoplasm enters the food vacuole along with the food. In the digestion of food more than one enzyme participates. It is however not known definitely which enzymes take part and what their order is. It is assumed that there is a possibility of the presence of protease, lipase and carbohydrates enzymes. The enzyme named protease is secreted when food remains in an acidic medium inside the food vacuole. It converts the complex protein food into simple peptides.
When the food vacuole becomes alkaline, the enzyme peptidase becomes active. Due to this reaction peptide is transformed into amino acids. Lipase transforms the fat portion of the food into fatty acid and glycerol. The enzyme amylase acts on the carbohydrate part of the food and transforms it into glucose. As the digestion process continues, the form of the food material is gradually changed.
Through the actions of enzymes complex food materials areconverted into simple materials. These simple food components inside the food vacuole are absorbed by the endoplasm.
Inside the endoplasm of amoeba, the digested food is absorbed andthe remainder is stored in the food vacuole. The food vacuole gradually approaches to the cell membrane of the body opposite to pseudopodia. At one stage the contents of the vacuole are thrown outside the body through the plasma membrane.