Discovered by Robert Hooke in 1665, the cell is the central and basic unit of life. Cells are of various shapes and sizes, and are composed of small organelles that perform distinct functions. Every cell is composed of cytoplasm which is a jelly-like substance that fills the body of the cell. The nucleus is one of the main organelles which guides the functions performed by the others.

The structure and functions of the nucleus

• The nucleus is found in the centre of the cell. 
• It stores the genetic information of the organism in eukaryotic cells.
• The nucleus is covered and separated from the cytoplasm by the nuclear membrane. 
• The nucleus helps replicate the DNA. 
• It overlooks the process of cell division, vital for the growth of the organism. 
• The process of transcription also occurs in the nucleus of the cell. 

Cellular functions

The various functions performed by a cell are listed below:

Transport and barrier

The cell membrane that surrounds each cell protects it from harmful bacteria and viruses. It has a semi-permeable membrane that selects the components that enter or be kept out of the cell.

Cell signalling

Cell communication and response to stimuli from the environment is one of the important functions of the cell. These signals are in the form of chemicals, which can be endocrine, paracrine, or autocrine. They trigger the cell to change something immediately or long-term. Some immediate responses, change in the metabolism of the cell and electrical charges of the cell.

Movement and migration of the cell

Cell movement or migration refers to the ability of the cell to move from one place to another. When the cell is divided, it migrates to form tissues of various organs. For instance, white blood cells move towards the injury when there is a cut in any body part.

Digestion

The process through which a cell engulfs and digests other substances is called endocytosis. When the cell engulfs any bacteria or other substance, it is covered in a vacuole. When the vacuole fuses with a lysosome, the cell is digested by the digestive enzymes present.

Metabolism

Metabolism refers to the chemical and physical processes that include the breakdown of macromolecules into simpler forms (catabolism), and the constitution of macromolecules (anabolism). 

Cell division and cell cycle

Cell division is an important process for the growth of the body. When a cell divides, it receives the same amount of genes, and other organelles to perform similar functions.

Conclusion

The cell is the basic unit of life and performs many functions like lipid (fat) and protein synthesis, cell division and respiration, replication, ion transportation, and metabolism. It also provides tissues with structural support, filters out harmful substances, and protects the body from sickness and injury.