The cell is the smallest unit in the structural hierarchy of life that performs every work necessary for life (Reec, Urry, Cain, Minorsky, Jackson & Wasserman, 2009). This cell works with other cells in a system to perform other complex processes by dividing the functions of performing complex work into groups of cells. For example, the process of readers' eye movement while reading this research occurs due to the activity of muscle and nerve cells (Reec et al., 2009). Furthermore, every process of performing complex work in which cells take part occurs due to the division of the functions of the particular cell between its parts. One of the parts of the cell is the cell membrane which has many organelles and these organelles are the same in the animal cell which is the human cell type. The important organelles in the cell membrane are the cell nucleus and the mitochondria. All these organelles perform work next to each other in the cell to work as a whole in carrying out the work of the cell in the human body such as the nerve or muscle cell. Therefore, to explain the activity that the cell membrane and every important organelle within it perform to take part in the main activity that the cell performs to carry out other complex jobs, this research will explain the cell membrane, cell nucleus and mitochondria individually. First of all, the cell membrane, or as it is sometimes called the plasma membrane, is the cell boundary that separates the cell from the environment around it. The cell membrane is one of the cellular parts that help the cell not be affected by other variables that try to enter inside it. According to Harrison and Lunt (1980) who wrote Biological Membranes; the... center of the paper... filters RNA and portions because it has two membranes, which have some proteins that recognize RNAs and other portions. Furthermore, mitochondria are the last parts of the cell, which are important for all cell parts because they produce the energy for the cell. Mitochondria have a structure that allows them to produce ATP in the cell. The amount of ATP produced by mitochondria in the cell depends on the number of mitochondria present in the cell. The amount of mitochondria depends on the function of the cell determined by the cell's nucleus, and this is the relationship between the mitochondria and the nucleus. Finally, all these organelles work side by side and carry out a complex process like being a red blood cell or a nerve cell (blood or nerve cell) with some functions that the cell as a whole is responsible for carrying out..