What is Cell Biology?

The study of the structure of the cell and its function is known as cell biology, and it is based on the idea that the cell is the most basic unit of life. The concept of cell biology is considered highly significant in the field of science, specifically in molecular biology. Concentrating on the biology of the cell by several kinds of research allows for a more in-depth study of the tissues and cells.

Why is Cell Biology Important?

Cell is the basic structural and functional unit of a living organism. Cell biology is an important concept that helps to understand the nature of the cell in detail. In specific, it performs a major role in the molecular aspect of biology. Molecular biology is the biological field which focuses on the molecular basis of different biological functions and activity.

Cell biologists perform research on plants to produce high-quality plants (to increase the crop productivity or resistance to pests) and animals to have better understanding of different cells in different organisms or cells within the same organism performing different functions. Cell biologists can collaborate their work with medical sciences and will be able to produce new drugs depending on the cellular targets, Cell biology includes the study of both prokaryotic and eukaryotic cell that can be broken down into a variety of sub-topics in science, such as cell metabolism, biochemistry, and structure of the cell, and so on.

Study and Research on Cell Biology

The 1830s may be considered as the beginning of this discipline. Even though, scientists had been using microscopes for decades, they were unaware of the cell that forms the life. In 1665, Robert Hooke observed cell walls of plants in slices of cork, which was quickly followed by Antonie van Leeuwenhoek's first observations of live cells with clearly moving sections. He observed protozoa and bacteria. In the 1830s, two colleagues — Schleiden, and Schwann presented the first concrete description of the cell. All living organisms, both basic and complex, are made up of one or more cells, and the cell is the functional and structural unit of life, which is known as cell theory.

Due to the invention of microscopes and different staining techniques in the nineteenth and twentieth centuries, scientists were able to view internal details of the cells. Van Leeuwenhoek's microscopes magnified specimens by a factor of a few hundred. Today's high-powered electron microscopes can magnify specimens by more than a million times and expose organelle shapes on the micro meter scale and below. A collection of images may be combined with confocal microscopy, enabling researchers to create an accurate three-dimensional representation of cells. These advancements in imaging techniques have enabled us to gain a deeper understanding of the complexity of cells and the structures they form.

Biological Subfields of Cell Biology

Cell biology is divided into many biological subfields. The study of cell energy and the biological processes that sustain cell metabolism is one such example. The study of cell energy intersects with the study of how energy first emerged billions of years ago in primordial cells. Another branch of cell biology is cell genetics, which is closely linked to the proteins that synthesized from the genetic material present in the nucleus. The messenger ribonucleic acid (mRNA) is translated into proteins in the cell cytoplasm. Another subfield focuses on the arrangement of subcellular compartments, which are cell organelles.

The additional subfield of cell biology, which is concerned with cell communication and signaling, focuses on the signals that cells send to and receive from other cells. And further, the biological subfield of cell biology also significantly deals with the functioning and regulation of the cell cycle. Cell cycle are the series of events which result in the formation of daughter cells from the parent cell. As our ability to study cells in more complex ways grows, many biologists work and research at the intersection of two or more of these subfields.


Cells are the simplest and most essential unit of life. The cell forms the smallest independent component of a living organism.

Cells act as the building blocks of all living things. They may be made up of a single cell (unicellular) or a many cell (multicellular). Mycoplasmas are the tiniest cells identified. All living things are composed of cells. The structure of the body and energy requirement is regulated by the metabolism of the cell.

Types of cells

Based on their structure, cells are classified into two types. Prokaryotic and eukaryotic cells depending on their membrane structure and internal structure.

  • Prokaryotic cells do not have a membrane-bound nucleus or other cell organelles. The organisms which are composed of prokaryotic cell are called prokaryotes. These organisms are unicellular.
  • Eukaryotic cells have the nucleus which is enveloped by a nuclear envelope and cell organelles such as mitochondria, endoplasmic reticulum, chloroplast and many more. Plants, animals and fungi are eukaryotes consisting of eukaryotic cells. These organisms can be unicellular or multicellular.
"Difference between prokaryote and eukaryote "

There are certain eukaryotic cells which have the ability to divide and differentiate into different types of cells. These cells are referred to as stem cells. Stem cells can originate from 2 sources namely embryo and adult tissues of the body and are referred to as embryonic (example, blastocyst) and adult stem cells (example, hematopoietic stem cell which gives rise to different blood cells) respectively.

Cell Structure

Individual components or organelles of the cell perform specific functions which are important to carry out various cellular processes and maintain the cellular structure. The cell membrane, cytoplasm, nucleus, and cell organelles such as Golgi apparatus, mitochondria are among these components.

Cell wall

  • It is the most visible component of the structure of the plant cell. It consists of three components: pectin, hemicellulose, and cellulose. The cell wall is also found in bacteria (prokaryotes) as well as fungi (eukaryotic microorganism).
  • Cell wall provides support and protection to the plasma membrane, and other cellular components. It is also defined as the outermost layer. It provides shape to the cell and also shields the cell from mechanical shock and injuries.


  • Within the membrane of the cell, the cytoplasm is a dense, translucent, jelly-like material. It is the site where the majority of a cell's chemical reactions take place.
  •  In the cytoplasm, cell organelles such as the vacuoles, mitochondria, and ribosomes are suspended. In case of prokaryotes, the genetic material and enzymes are present in the cell cytoplasm

Cell membrane

  • The cell membrane separates the intracellular environment from the extracellular environment and helps in maintaining cellular homeostasis. It acts as a barrier between the cell and the outside world. This is found in every cell.
  •  It is the cell's outer shell, which encloses all other organelles such as the cytoplasm and nucleus. The plasma membrane is another name for it.
  • It is a semipermeable membrane that allows selective substances to pass into and out of the cell.
"Structural representation of the cell membrane"


  • The cell's genetic material, DNA (deoxyribonucleic acid), is found in the nucleus. In prokaryotes nucleus is not present and the DNA is freely present in the cell cytoplasm.
  •  It is involved in cell signaling which eventually results in cell division, cell differentiation, and apoptosis.
  • The nuclear envelope separates the DNA from the rest of the cell and surrounds the nucleus.
  •  The nucleus protects the DNA and is an essential part of the structure of the cell. DNA replication and transcription (RNA synthesis) occur in the nucleus.
"Structure of Nucleus"

Endoplasmic reticulum

This is responsible for transporting materials across the cell. It is important for carbohydrate metabolism, lipid synthesis, steroid synthesis, and protein synthesis. The proteins which are destined for different cell organelles, plasma membrane or outside the cell are synthesized in endoplasmic reticulum.

Golgi bodies

The Golgi body is the communicating center of the cell, which is involved in the modification and transportation of materials between the cell organelle or to the plasma membrane.


The mitochondrion is the site for the generation of ATP (adenosine triphosphate) which is required by the cell to perform various metabolic functions. Since, ATP is considered the energy currency, mitochondria is considered as the powerhouse of the cell.


Lysosomes aid in cell renewal and protect the cell by engulfing foreign bodies such as bacteria, cellular debris etc. that invade the cell. As a result, it is referred to as the cell's suicide bags.


The main organelles for photosynthesis are chloroplasts. It contains chlorophyll pigment. It is only found in plants. Due to the presence of chloroplasts, plants are considered autotrophs (organisms able to synthesize their own food).

Context and Applications:

This topic is significant in the professional exams for both undergraduate and graduate courses, especially for      

  • B.Sc. (Bachelor of Science) Biochemistry
  • B.Sc. Plant Biology
  • M.Sc. (Master of Science) Biochemistry
  • Molecular biology
  • Biochemistry
  • Cellular basis of inheritance
  • Biochemistry
  • Cell genetics

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