Describe the structural features of unicellular animals.

The inner part of a single-celled organism is filled with a liquid that is chemically different from the environment outside the cell, which allows biological processes to take place in a state of imbalance with the world outside the cell. In addition, all the insides of one element in the body contain some degree of design complexity with various parts dedicated to specialized functions such as nutrient absorption and protein synthesis. In order to maintain a state of imbalance with the external environment, which characterizes the existence of any organism, there must be a barrier in its biology that separates the internal elements of the cell from the outside world, known as the cell wall. It is a permeable membrane that regulates the movement of nutrients and cellular waste into and out of the cell.