Animals, plants and microorganisms are always among us. Just like us they are also living beings who perform various tasks similar to humans. There are thousands of differences between animals, plants, microorganisms and human beings, although, there is something common to all living beings in the universe.
Yep! It is the Cell.
The Cell Theory
Belgium botanist, Matthias Schleiden and German zoologist, Theodor Schwann revealed lot of information about cells in 1938. These 2 scientists were able to discover the cell theory, Schleiden discovered the plant cell theory while Schwann discovered the animal cell theory.
This discovery was a turning point of Biology, later many scientists contributed to this Cell theory.
According to Cell theory, the basic unit of structure and function in living organisms is the cell. And all the living organisms are made of one or more cells while new cells are arising from the existing cells of a living body. This whole thing includes in the cell theory founded by Schleiden and Schwann.
Observing Cells Under Microscope
A cell is a very tiny structure which exists in living bodies. You can’t see any cell with your naked eye, because they are very smaller than what human eyes can see normally. This is the reason why you need to use a microscope to observe a cell.
You know what, the onion cells look like bricks of a parapet wall when you see it under the low power of microscope. However, it does not appear to be parapet wall bricks under the high power of microscope.
You’re made from millions of tiny cells, but you can’t take out a couple of cells in your hand or leg easily without any pain. Even though it looks we can’t take any cell out without feeling a pain, actually we can take out the cells in your mouth easily.
Your internal surface of the mouth is surrounded by Epithelial Cells which you can take out by your finger nails or using a small spoon. Of course, these epithelial cells in your mouth can be observed under a microscope in its high power. Epithelial cells have a shape of spherical with a spherical structure of granulated area within the cell.
The large spherical area is the Nucleus while the granulated part is the Cytoplasm of the cell. These are all common parts of a cell. In the above observation of onion cells, you can see the Cell Surface Membrane which is consisted in any living cell.
Generalized Structure of Animal Cell & Plant Cell Under Microscope
You already know the fact, the cell is the basic structural and functional unit of living beings. This means a cell does various tasks that it was designed to accomplish. Not every cell is the same copy of other. The cell structure must be adapted and changed according to the function it does in the body.
This is known as Division of Labor which is presented in any living organism. This is the reason why your palm has a thicker skin unlike the skin of your face. Palm – Made from lots of cells – is designed to grip things and so it is thicker than other parts of the skin.
And it is the same reason for your heart to distribute the blood throughout the body, lungs to transport Oxygen into the body while getting Carbon Dioxide out of the body and so on!
A high efficiency is available for the cells to perform their functions when the structure is adapted according to its function. If you are into video gaming, you know that your ordinary laptop cannot play the best video games, because it is not designed to play games.
But you can play games on your gaming rig because it has the goodies needed to perform the function of ‘Running the game!’
I hope you realize my point above. If not, read the last 2 paragraphs again.
Plant leaves are capable of doing something highly important to earth. As you guessed, it is Photosynthesis. The most required part for the Photosynthesis is Chlorophyll which is contained in the cells of plant leaves. In other words Chlorophyll is appearing only on plant leaf cells, it does not appear in the cells of roots.
Perhaps, you may realize that there are many parts of the cells depending on the function. However for easy learning of the basic unit of structure of the cell, the scientists introduced the Generalized Cell structure which contains all the identified common parts of cells.
Generalized Cell is used for structure of Animal Cell and Plant Cell to present the common parts, appear in various parts of the bodies of animals and plants.
There are various parts of the cell are known as Organelles – Subunits of the cell that performs its own sub functions to help the cell to do its job well.