Cell: Introduction and Discovery

Let us do some travelling to the time when we were trying to discover new facts.

It’s 17th century, and we are here in the lab of Antonie Van Leeuwenhoek, who is a scientist by profession.

He is doing something with a biconvex lens.

He is preparing a Simple Microscope to examine the webbed feet of a frog.

This microscope is different from the Compound Microscope we have in schools.

Microscopes give magnified image of objects which are too small to be seen with our naked eyes.

Leeuwenhoek used the microscope to study the internal structures of the body like blood capillaries of frog.

In the frog’s capillaries, he saw something which was not seen before by anyone.

What he saw were small units but he could not give any name to it.

Now we will travel to 1665 to know more about the small unit that was seen by Antonie.

Now, we are in the lab of a famous scientist whose name is Robert Hooke.

We can see that he is also making a microscope but in a different way.

He used 2 lenses instead of 1 to make the microscope.

Now he takes out some cork (dead part of the bark of the tree) and puts it under the microscope to study it.

He observes that the dead cork is made up of box-like compartments.

Each compartment has a shape similar to the cell where monks live and hence Hooke named it as ‘Cell’.

We shall now learn more about Cells.

A building is made up of a number of bricks.

Similarly, we are also made up of a number of ‘cells’. Cells are like the bricks of our body.

Every organism starts from a single cell which divides into more cells to form the complete individual.

So, we can say that a cell is the basic unit of life which acts as building blocks in all the living beings.

Cell is also called the functional unit as all the functions of the body are carried out by cells.

So, we can say that the cell is the functional and structural unit of life.

The scientific study of cell is called Cytology.

It will be interesting to note that a cell also dies just like any other living being.

For example, when we discussed about Hooke’s experiment, we said that he observed dead cork.

It means that the cells which made the cork were dead and they didn’t have any living substance in it.

But the cells seen by Antonie Van Leeuwenhoek were living blood cells in the capillary of the frog.

This substance necessary for a cell to live is called the protoplasm.

This protoplasm is jelly- like in appearance and is made up of 2 parts- cytoplasm and nucleus.

The cell nucleus​ is the most important part of the cell which controls all the functions of the cell.

The cytoplasm is a thick solution that fills each cell and contains all the cell organelles.

The cytoplasm and nucleus are thus, essential parts of a cell.

Revision

Cell is the functional and structural unit of life.

Cell was first seen by Antonie Van Leeuwenhoek and was named by Robert Hooke.

Cell has a living substance protoplasm which is made of cytoplasm and nucleus.

The End