The cell is the smallest unit in the structural hierarchy of life that performs all the work necessary for life (Reec, Urry, Cain, Minorsky, Jackson & Wasserman, 2009 ). This cell works with other cells in a system to carry out other complex processes by dividing the functions of performing complex work into groups of cells. For example, the process of readers' eye movements while reading in this research is due to the activity of muscle and nerve cells (Reec et al., 2009). Moreover, each process of performing complex work in which cells participate occurs due to the division of functions of the cell, especially between its parts. One of the cell parts is the cell membrane which has many organelles, and these organelles are the same in the animal cell which is of the human cell type. The important organelles of the cell membrane are the cell nucleus and the mitochondria. All these organelles carry out work side by side in the cell to work as a whole to carry out the work of the cell in the human body, such as being a nerve or muscle cell. Therefore, to explain the activity that the cell membrane and each important organelle inside the cell membrane do to participate in the main activity that the cell does to carry out other complex works, this research is going to explain the membrane cell, the nucleus of the cell. , and mitochondria individually. First of all, the cell membrane, or as it is sometimes called the plasma membrane, is the boundary of the cell that separates the cell from the environment around it. The cell membrane is one of the cellular parts that helps the cell not to be affected by other variables trying to get inside the cell. According to Harrison and Lunt (1980) who wrote Biological Membranes; the...... middle of paper......filtering RNA and portions because it has two membranes, of which they contain proteins that recognize RNA and other portions. Moreover, mitochondria are the last parts of the cell, which are important for all cell parts because they produce the energy needed by the cell. Mitochondria have a structure that allows them to produce ATP to 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 nucleus of the cell, and it is the relationship between mitochondria and the nucleus. Finally, all these organelles work alongside each other and carry out a complex process, such as being a red blood cell, nerve cell, blood or nerve cell, with certain functions that the cell as a whole is responsible for accomplishing..