The plasma membrane regulates the flow of materials in and out of the cell. Some organisms, such as paramecia and amoebae are single cells that feed, grow and reproduce as completely autonomous individuals. Several kinds organelles, each having different functions, exist together in the protoplasm of a cell. The Golgi complex stores and packages protein products. The nucleus of the cell is where the Chromatin and DNA are kept.
Cell types can vary among species and within a single individual.
The following figure shows some of the different types of cells found in a human being.