Cell - Structure and Function

Introduction to Cell


Ever thought what living organisms composed of? Or rather what is it that makes us living beings? Here comes the introduction to Cell. The cell is the smallest structural unit of a living organism. So, everything that we are able to do is possible because of the 10 trillion cells present in our body. The number is huge and of course, the function performed by them is even bigger. In this topic here, we’ll introduce you to cells. Let’s begin.

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Introduction to Cell

The introduction to cell began back in the year 1655 when a revolutionary observation was made by an English scientist Robert Hooke. This observation made by him was so huge that it went on to change the basic biological theory and research forever. So, how was the cell discovered?

Robert Hooke was examining a dried section of the cork tree using a crude light microscope. In this analysis, he observed multiple small chambers which he named the cells. Thereafter, over the next 175 years, several kinds of research were made which led to the formation of the cell theory that we know today.

Introduction to Cell

The first such theory was proposed by the German botanist Matthias Jacob Schleiden and the German physiologist Theodore Schwann in 1838. This theory was formalized in the year 1858 by the German researcher Rudolf Virchow.

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Cell Theory

  • The cell is the basic functional and structural unit of life. All the living organisms are composed of cells.
  • All cells are formed by the division of the already existing cells which in terms of biology means reproduction. Every cell of our body comprises of genetic material which is passed down during the process.
  • All the basic physiological and chemical functions i.e. the growth, repair, movement, communication, immunity and digestions are performed inside the cells.
  • All the activities of the cell depend mainly on the activities of the subcellular structures that lie within the cell. These subcellular structures comprise of the plasma membrane, organelles and if present, the nucleus.

What are Cells?

Here is the revised introduction to cell. In all the living beings, cells are the basic structural units. We can compare the presence of cells in our body to the bricks in a building. All the bricks are assembled to make a building. Similarly, all the cells are assembled to make the body of an organism.

Thus, it is the basic structural and functional unit of life and all the organisms are made up of cells. The subcellular structures of the cell comprise of the plasma membrane, organelles and in some cases a nucleus as well. As for the size of the cell, it is variable and maybe anything from 1 to 100 micrometre.

How Are Cells Produced?

Every cell is produced by the division of a cell that is already existing in our body. This is possible because of the genetic material contained in the cell. The genetic material is passed down from one cell to another during the reproduction process. Unlike the non-living bricks, the cells of the living organisms are rather complex living structures. Therefore, the cells can divide the genetic material and form two new cells.

introduction to cell

Types of Cell

Broadly, there are two key types of cells i.e. the Prokaryotic Cell and the Eukaryotic Cell. The difference between the two is defined mainly by the presence or the absence of the nuclear membrane. Let’s know more about the two types of cells.

 1) Prokaryotic Cell

If a cell has a nuclear material without a nuclear membrane, then it is known as the prokaryotic cell. Those organisms which have these type of cells are commonly known as the prokaryotes where ‘pro’ stands for primitive and ‘karyon’ stands for the nucleus. Some of the organisms that have prokaryotic cells include bacteria and the blue-green algae.

 2) Eukaryotic Cell

If a cell has a nuclear material with a nuclear membrane, then it is known as the Eukaryotic Cell. Those organisms which have these type of cells are commonly known as eukaryotes where ‘eu’ stands for true and ‘karyon’ stands for the nucleus. All the living organisms except bacteria and blue-green algae have Eukaryotic Cells.

Question For You

Q: Why is cell the fundamental unit of life?

Ans: A cell is capable of independent existence and can carry out all the functions which are necessary for the existence of the living being. Some of the functions that are performed by the cell include nutrition, respiration, excretion, transportation and reproduction.

These functions are very similar to the functions of the individual organism. Even the unicellular organisms are capable of independent existence. This proves the capability of the cell to exist independently. Therefore, a cell is the structural and fundamental unit of life.

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