Cell Theory

Every living being is made up of cells. A mass of cytoplasm bound externally by the cell membrane is called a cell. This fundamental is the base of cell theory. Cells are microscopic, and they are the smallest structural unit of all living things. Most of the cells have one or small nuclei and other organelles. These organelles carry out different tasks that are the essential functions of the cell’s life.

Cells like bacteria or yeast are complete organisms. Some other cells are building blocks of multicellular organisms. Plants and animals are examples of multicellular organisms. 

What is Cell Theory?

• Structure of a cell 

Cell theory states that the cell is the fundamental structural and functional unit of living organisms. Theodor Schwann, a German physiologist, and Matthias Schleiden, a German botanist in 1839, explained that cells are the elementary particles of living organisms. These scientists made the cell theory popular. Cell structure determines that some organisms are unicellular while some others are multicellular. Cell theory was later expanded  by Rudolf Virchow. According to it -All plants and animals are composed of cells.Cell is the functional unit of life.All cells arise from pre-existing cell( omnis cellula -e- cellula)

• Size of a cell 

Although Cells are much larger than atoms, they are minuscule. Mycoplasmas are a group of tiny bacteria that has the smallest cells. Human cells are only about 20 μm in size. It would be interesting to know that at least ten thousand human cells will be required to cover the head of a small pin. 30,000,000,000,000 cells make a complete human organism. A cell can be defined as an individual unit and a contributing unit of a larger organism. A cell has its metabolism. It synthesises many types of molecules and provides energy to itself. 

• Reproduction in a cell 

Not only this, a cell replicates itself to produce the next generations of the cell. A lot of chemical reactions keep taking place within it. These reactions are helpful to the life of the cell and the procreation of the cell. 

In a multicellular organism, a cell adopts the function of differentiation. It keeps constant communication with the neighbouring cells, receives nutrients, and releases the waste material into its surroundings. Cells always cooperate with other cells, and these cooperative assemblies of cells are called the tissues. Further, tissues cooperate, and this cooperation forms organs. These organs carry out the life-sustaining functions of a living organism. 

Functions of a cell 

• Ingestion 

The plasma membrane of the cell functions as a barrier that allows nutrients to enter and waste products to leave. The interior of the cell is composed of many special compartments known as organelles. A separate membrane encloses each one of these. One such organelle called the nucleus contains the genetic information necessary for cell growth and reproduction. 

• Major organelles 

Each cell contains only one nucleus. Other types of organelles are present in the cellular content called the cytoplasm. Mitochondria is one such organelle responsible for the energy supply necessary for cell survival. Lysosomes digest the unwanted material within the cell. Two other important organelles are the endoplasmic reticulum and Golgi apparatus. 

Endoplasmic reticulum and Golgi apparatus synthesise the molecule and the n process, sort, and direct them to their locations. In this way, they manage the internal organisation of the cell. In plants, the chloroplast is responsible for food making photosynthesis. 

• Shape and movement of a cell 

The space between all the organelles is called cytosol. The cytosol has a fibrous molecule system that constitutes the cytoskeleton, and this further gives a cell its shape enabling organelles movements and movements of the cell itself. The cytosol has ten thousand different kinds of molecules that are part of making bigger biological molecules from the smaller ones. This process is called biosynthesis. 

Every cell contains a special collection of molecules enclosed by a cell membrane. These molecules enable the cell to grow and procreate. Cellular reproduction has two steps:

1.  Cell growth 
2.  Cell Division 

Molecular Structure of a Cell

These complex molecules are composed of chains and rings of hydrogen, oxygen, nitrogen, and carbon atoms. Besides water, which is 70% of the cell’s mass, a cell is composed of macromolecules. These macromolecules are mostly made up of proteins. 

Conclusion-

Every living being is made up of cells. A mass of cytoplasm bound externally by the cell membrane is called a cell. This fundamental is the base of cell theory. Cells are microscopic, and they are the smallest structural unit of all living things.Not only this, a cell replicates itself to produce the next generations of the cell. A lot of chemical reactions keep taking place within it.Each cell contains only one nucleus. Other types of organelles are present in the cellular content called the cytoplasm. Mitochondria is one such organelle responsible for the energy supply necessary for cell survival.