Definitions of a Cell

Definition

According to Biology Online, a cell can be defined as an autonomous self-replicating unit that may exist as a functionally independent unit of life or as a sub-unit in a multicellular organism that specializes in carrying out particular functions. The human body contains about 100 trillion cells.

Over millions of years, cells have evolved to contain the most intricate of structures within themselves. These structures serve specific purposes in an interconnected network to make the cell operate like a simple machine. Each internal structure must cooperate with each other to ensure the ultimate survival of the cell.

The cell is considered the basic unit of all living organisms. As a self-maintaining and self-contained unit, it can convert certain nutrients into energy and perform certain functions, the main function being the ability to reproduce through cell division, the use of enzymes for various processes and the maintenance of cellular metabolism.

There are millions of different types of cells, but they all fall into two basic categories: prokaryotic cells, such as bacterial cells, and eukaryotic cells, which are plant or animal cells. A eukaryotic cell is different from prokaryotic cells in a major way. Eukaryotic cells have a well-defined nucleus surrounded by a membrane.

Some of the main features of a cell are the cell membrane (which are like the outer walls containing the cell body), the nucleus (which is where the chromosomes are located and where almost all the genetic code replication and synthesis occurs), and various other components such as mitochondria and ribosomes. Chromosomes are thread-like structures made of protein that contain a single molecule of deoxyribonucleic acid (DNA), which holds the specific instructions that make each type of living creature unique. Mitochondria are the energy factories of the cell, and ribosomes are responsible for assembling the proteins in a cell. Each feature in a cell allows it to perform its overall function.