What Is A Cell? Define Its Structure, Types, Functions

What Is A Cell

Definition Of Cell

Cells are the structure, function, and biological unit of all living things. A cell can replicate independently. Therefore, they are called the corners of life.

Each cell contains a fluid called the cytoplasm, which is surrounded by a membrane. The cytoplasm also contains many biological molecules, such as proteins, nucleic acids, and lipids. In addition, cellular structures called organelles are suspended in the cytoplasm.

What Is A Cell

Cells are the structure and the basic unit of life. The study of cells from the basic structure to the function of each structure is called cell biology. Robert Hooke was the first biologist to discover cells.

All living things are made up of cells. They may be composed of a single unit (single cell) or several units (multiple cells). Mycoplasma is the smallest cell known. Cells are the cornerstone of all living things. They provide structure for the human body and convert the nutrients absorbed in food into energy.

Cells are complex, and their components perform various functions in the organism. They have various shapes and sizes, similar to the bricks of buildings. Our body is made up of cells of different shapes and sizes.

Cells are the lowest layer of tissue in each life form. From one organism to another, the number of cells may vary. Compared to bacteria, humans have many cells.

Cells comprise several organs that perform specific functions to perform life processes. Each organization has a specific structure. The genetic material of organisms is also present in cells.

Types of Cells

The units are similar to factories with different workers and departments, and they work towards a common goal. Different types of units perform different functions. According to cell structure, there are two types of cells:

  • Prokaryotes
  • Eukaryote

Explore: The difference between prokaryotic and eukaryotic cells

Prokaryotic cell

Prokaryotic cell
  • Prokaryotic cells are non-combined. Instead, some prokaryotes (such as bacteria) have a region within the cell where genetic material can be freely suspended. This region is called nucleoside.
  • They are all single-celled microorganisms. Examples include Achaea, bacteria, and cyanobacteria.
  • Cell sizes range from 0.1 to 0.5 μm in diameter.
  • Genetic material can be DNA or RNA.
  • Prokaryotes reproduce through binary fission, a form of sexual reproduction.

Eukaryotic cell

Eukaryotic cell
  • Eukaryotic cells are characterized by a true nucleus.
  • Cell sizes range from 10–100 μm in diameter.
  • This broad category includes plants, fungi, protozoa, and animals.
  • The plasma membrane is responsible for monitoring the transport of nutrients and electrolytes into and out of the cell. It is also responsible for communication between cells.
  • They breed both sexually and non-sexually.
  • There are some sharp contrasts between plant and animal cells. For example, plant cells have chloroplasts, central vacuoles, and other plastids, whereas animal cells do not.

Cell Structure

Cell structure consists of individual components with specific functions that are necessary for the execution of life processes. These components include the cell wall, cytoplasm, nucleus, and organelle. Read on to find out more about cell structure and function.

Cell Membrane

  • The cell membrane supports and protects the cell. It controls the movement of substances inside and outside the cells. This separates the unit from the external environment. Cell membranes are present in all cells.
  • The cell membrane is the outer covering of the cell, and all other organs (such as cytoplasm and nucleus) are attached to it. It is also called the plasma membrane.
  • Structurally, it is a porous membrane (with pores) that allows selective materials to move in and out of the cell. In addition, cell membranes also protect cell components from damage and leakage.
  • This creates a wall-like structure between the two units and between the unit and the surrounding environment.
  • Plants are stable, so their cell structure is very suitable to protect them from external factors. The cell wall helps to increase this function.

Cell Wall

  • The cell wall is the most prominent part of plant cell structure. It is composed of cellulose, hemicellulose, and pectin.
  • Cell wall is found only in plant cells. It protects the plasma membrane and other cellular components. The cell wall is also the outermost layer of plant cells.
  • It is a rigid structure around the cell membrane.
  • It provides size and support for the battery and protects it from mechanical shock and damage.


  • The cytoplasm is a thick, transparent, succulent substance present in the cell membrane.
  • Most of the chemical reactions in the cell are in cytoplasm.
  • Organelles such as the endoplasmic reticulum, Vocal, mitochondria, and ribosomes are suspended in the cytoplasm.


  • The nucleus contains the genetic material of the cell, called DNA.
  • It sends signals to cells to grow, mature, divide and die.
  • The nucleus is surrounded by a nuclear membrane, which separates DNA from the rest of the cell.

The nucleus protects DNA and is an integral part of the cell structure of the plant.

Functions of Cell

Cells perform these main functions, which are necessary for the growth and development of organisms. The important functions of the unit are as follows:

Provides Support and Structure

All living things are made up of cells. They form the structural basis of all living things. Cell walls and cell membranes are the main functions, providing support and structure for living things. For example, the skin is made up of a large number of cells. The vascular is made up of xylem cells present in plants that provide structural support for plants.

Promote Growth Mitosis

During mitosis, the parent cell is divided into daughter cells. Therefore, cells multiply and promote the growth of organisms.

Permitted substance

Cells absorb various nutrients to perform various chemical processes inside cells. Waste produced by the chemical process is eliminated from the cell through active and passive transport. Small molecules such as oxygen, carbon dioxide, and ethanol diffuse through the cell membrane along a concentration gradient. This is called passive transmission. Larger molecules diffuse through active transport across the cell membrane, in which case much more energy is required to transport the substance to the cell.

Energy Production

Cells require energy to perform various chemical processes. This energy is produced in cells through photosynthesis and by the respiration of animals.

Aids in Reproduction

Cells help in reproduction through mitosis and meiosis processes. Mitosis is called asexual reproduction, in which the parent cells divide to form daughter cells. Mayonnaise cells are genetically differentiated due to meiosis. Therefore, we can understand why cells are called structural and functional units of life. This is because they are responsible for providing the structure for organisms and performing many tasks necessary for the execution of life processes.

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