Cell – Discovery, Structure, Size and Types

What is cell?

Cell forms the lowest level of organisation which has life. This label of organization is called cellular level.

The cell is the structural and functional unit of life. A cell can replicate itself independently. Hence, they are known as the building blocks of life. 

All organisms are made up of cells. They may be made up of a single cell (unicellular), or many cells (multicellular).

Mycoplasmas are the smallest known cells. Cells are the building blocks of all living beings. They provide structure to the body and convert the nutrients taken from the food into energy.

Cells are complex and their components perform various functions in an organism. They are of different shapes and sizes, pretty much like bricks of the buildings. Our body is made up of cells of different shapes and sizes

Discovery of Cell

Robert hooke, an englishman discovered the cell in 1665.

Soon after this Antonio made further discoveries by inventing his own microscope lenses that were more powerful than the microscopes of his time. He was the first person to observe human cells and bacteria under his microscope.

The science of cells has evolved ever since. Various scientists like Louis Pasteur, etc continued to bring new innovations to the field of science.

Types of cell

Cells are similar to factories with different labourers and departments that work towards a common objective. Various types of cells perform different functions. Based on cellular structure, there are two types of cells:

1. Prokaryotic Cell

A prokaryotic cell is a type of cell that does not have a true nucleus or membrane-bound organelles. Organisms within the domains Bacteria are based on the prokaryotic cell, while all other forms of life are eukaryotic. However, organisms with prokaryotic cells are very abundant and make up much of Earth’s biomass.

Prokaryotes, like bacteria, are single-celled organisms. Prokaryotic cells are smaller than eukaryotic cells, and they don’t have a membrane-bound nucleus.

2. Eukaryotic Cell 

A eukaryotic cell contains membrane-bound organelles such as a nucleus, mitochondria, and an endoplasmic reticulum. Organisms based on the eukaryotic cell include protozoa, fungi, plants, and animals.

These organisms are grouped into the biological domain Eukaryote. Eukaryotic cells are larger and more complex than prokaryotic cells found in domains Archae and Bacteria.

A eukaryotic cell is one of two different types of cells. Organisms that are based on the eukaryotic cell are called “eukaryotes” and include plants, animals, fungi, and protists. The only organisms that are not based on the eukaryotic cell are organisms based on a prokaryotic cell structure.

Those organisms are found in the domains Archae and Bacteria. There are several differences between a eukaryotic cell and a prokaryotic cell that can help you fully understand what makes a cell eukaryotic.

Size of the Cells

In multicellular organisms, cells have different shapes and size.

Each cell has its own unique role to play in helping the body function properly. The shapes of each cell help them to fulfill their roles effectively.

Living organisms are made up of different types of cells, of different shapes and sizes. A unicellular organism differs in shape from another unicellular organism. Within a multicellular organism, there are a variety of cells. Some are long while others are short; some are circular while some are oval.

Shape and size vary from cell to cell according to their functions and composition. For example, a nerve cell is long and branched, meant for the transmission of signals throughout our body while a muscle cell is small and spindle-shaped which helps in movement.