How do heterotrophic unicellular beings can get organic matter?

 When we are talking about how unicellular beings do their digestion, there are 3 main organelles we need to talk about: The cell membrane, the Golgi complex and the endoplasmic reticulum.
 It all starts on the endoplasmic reticulum that is involved on the synthesis of proteins, lipids and hormones. It is also involved on the transport of proteins and other substances. After the synthesis of the proteins, the vesicles or the tubules of the ER (endoplasmic reticulum) transport these proteins to the Golgi complex, where the vesicles membrane merges to the dictyosomes membrane.
 The Golgi complex is composed by many dictyosomes that have a convex and a concave side. The convex side is the formation face, and is where the proteins from the ER first arrive. They leave through the concave side, the maturation face. During this time, some proteins became functional and some enzymes became active. These enzymes form the lysosomes (vesicles with enzymes inside).
 When a cell finds his food, they take them into yourself through a process called endocytosis (there are some different types of endocytosis). With the cell membrane is formed an endocytic vesicle, that stats to be called digestive vacuole when it fuses with a lysosome. Is on that vacuole that the substances are digested and the products of digestion are released on the cell cytoplasm. The waste leaves the cell when that vacuole (now called secretory vesicle) merges with the cell membrane.