Four Functions of a Cell

The cell is the most basic unit of life. The body is composed of 200 different types of cells, each sustaining a specific role to maintain life. Each cell is comprised of similar components; for example, each cell is enveloped by a plasma membrane or “skin,” to protect the cell from the outer environment. At the center of the cell, is the nucleus containing the DNA, in addition to the organelles, or structures that carry out the day-to-day cellular functions, according to the Center for Biological and Biomedical Computing at Dartmouth University. Of the variety of cellular functions, cellular transport, protein synthesis, energy production and cellular replication are four important functions of the cell.

Cellular Transport

Tortora and Derrickson, in “The Introduction to the Human Body” write that cellular transport, or movement of materials across the plasma membrane, is essential to the life of a cell. Substances must enter the cell to support metabolic processes, and waste products must be removed. Substances such as nutrients and gases move through the membrane via a process called diffusion, a process characterized by movement of a substance from an area of high concentration to an area of low concentration. Diffusion can be a passive process, where materials freely travel through the membrane or diffusion can be facilitated, requiring a membrane protein to help the material enter or exit through the membrane. Materials that are too large to penetrate the cellular membrane can also enter and exit the cell via a small sac structure called a vesicle.

Protein Synthesis

Proteins accomplish the most important functions in a cell. Proteins are comprised of a number of amino acids, strung together and conformed to a specific shape. The production of proteins, also called translation, is dependent upon the DNA within the nucleus. The first step in protein synthesis is transcription, or the process of copying a segment of DNA code. The segment is then attached to a ribosome, a type of organelle within the cell, and translated into a new protein, according to Tortora and Derrickson.

Energy Production

Many cellular processes require energy in order to function. In actuality, energy is a molecule called adenosine triphosphate, or ATP. ATP is produced by the mitochondria, a type of organelle inside the cell. Many mitochondria are found within the cells of the heart, skeletal muscle, liver and kidneys--tissues and organs that require a large amount of energy to function. ATP is produced from glucose, amino acids and fatty acids within the mitochondria in a process called cellular respiration, according to the Scripps Research Institute.

Cellular Replication

Most cells within the body are reproduced on a regular basis, i.e., hair, skin and fingernail cells. Cellular replication, or mitosis, is the process of creating new cells for tissue growth, repair and replacement of older cells, and involves the replication of the DNA within the nucleus, followed by the separation of one cell into two distinct cells with equal DNA and organelle numbers. Cellular replication is cell specific; not all cells can undergo replication, i.e., brain and nerve cells do not replicate, according to the University of Maryland, College of Chemical and Life Sciences.