Cell Biology: Definition, Types, & Examples

Cell Biology Definition

A cell is the structural and functional unit of all living organisms. The organisms are mainly classified into two types: unicellular and multicellular. Unicellular organisms comprise a single cell whereas multicellular organisms are comprised of tissues and organs. Cell, its functions, and its organelles are studied under a branch of biology called cell biology. The topics such as DNA replication, protein synthesis, and cell defense are covered under cell biology.

Cell Biology Objective

  • To get knowledge about cellular organelles and cytoplasmic structures of the cell and understand their functions and composition.
  • To understand the various reactions and processes such as photosynthesis, DNA replication, translation, cellular respiration, and defense mechanisms.

What is Cell Biology?

  • An organism can be created only with a single cell. It consists of its ‘miniature machines’ or organelles that help to keep itself functional.
  • The process of generating ATP by degradation of sugar is called cell respiration. ATP is the major source of energy for all metabolic activities of the cell.
  • Green plants or autotrophs can produce their own food (sugar) by performing photosynthesis. They use inorganic molecules, light, and water to complete the process.
  • DNA is a double helical structure present in the nucleus of the cell. It is comprised of monomeric units called nucleotides. A nucleotide is made up of a phosphate molecule, deoxyribose sugar, and nitrogenous base. The particular protein is coded by the nucleotide sequence of DNA.
  • Protein synthesis also occurs within the cell by the process of translation. The process initiates with transcription of mRNA script within the nucleus which is later brought to the ribosomes and translated into an amino acid sequence. The protein then undergoes post-translational modifications in the endoplasmic reticulum and Golgi apparatus.
  • Viruses are defined as obligate parasites and “connecting link between the living and non-living organisms”. They need a living host to become alive.
  • Higher organisms including humans and animals can combat antigens and disease-causing pathogens by their immune systems. Whereas the immune system or any specialized cells are not present in plants, therefore, they use several strategies to defend themselves from pathogens. For example, they produce hydrogen peroxide or some other chemicals such as lignin, ethylene, galls, and tannins.
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