The Cell Unit Of Life

Introduction

Cells are the basic units of life because they are the smallest structural and functional units of all living things . 

Building blocks

Cells are the fundamental building blocks of all organisms whether they are made up of one cell like bacteria or many cells like humans . 

Independent existence

Cells can replicate themselves independently and carry out all the vital functions for living such as nutrition, respiration, excretion, transportation, and reproduction. 

Structure

Cells are surrounded by a cell membrane, which acts as a clear boundary between the cell's internal and external environments. 

 Discovery of cell

The English scientist Robert Hooke, in 1665, observed a tiny empty space in his glass bottom, which looked like a cell, so he named it cell as it looked like a bee's cell, which membrane was made of cellulose. Robert Hook published his work in his book  micrographia.Robert Hook is called the father of cytology.

Cell theory

Cell theory was given by schleiden and schwann in 1838-39. Schleiden was a German botanist while schwann was a british zoologist.

1.-   Every living being is made up of cells and their products. Cell is the smallest cell in which biological activity is completed and it can be called life.

2.-  Every cell is a mass of protoplasm which is surrounded from outside by cell membrane. Cell wall is found in plant cells.

3.-  All biological activities found in organisms take place inside the cells.

4-.  A cell is a genetic cell because it contains genetic material.

5.-  All cells are formed from precursor cells. The body of living organisms is made up of one or many cells.

Cell types

There are two types of cells

1.-  prokaryotic cell

2.-  Eukaryotic cell

1.-  prokaryotic cell

Nucleus and nuclear membrane are absent in prokaryotic cell. All organelles are not present in it. The substance of the nuclear material does not dissolve independently in the cytoplasm. Their chromosomes contain the expression of histone proteins.70 types of ribosomes are found in these cells.

Ex. Virus, mycoplasma, bacteria, blue-green algae,  etc. 

Eukaryotic cells 

True nucleus and fully developed cells are found in the eukaryotic cell. These are the types of cells that are made of eukaryotes. They have a nucleus inside them. The nucleus is a substance. Different cells are found in it, such as mitochondria golgi body etc. These cells produce chromatin, a genetic material made of nucleoprotein which In the form of chromosomes , it is found in the nucleus. 80.S  types of ribosomes are found in this cell. 

Ex. Protist, fungi, plant and animal cells. 

Structure of Eukaryotic cell

Ultra structure of the cell

Cell wall

It is the outer structure of the plant cell which protects and surrounds the cytoplasm.The plant cell wall of higher class plants is mainly composed of cellulose, in addition to which, hemicellulose is also found in lipids, minerals and other substances.

Function of cell wall

1.-  The cell wall provides a definite shape and strength to the cell.

2.-  It plays the role of external skeleton of the cell. 

3.-  It forms the permeable boundary of the cell. Hence, it allows water and solutes to enter the cell and thus helps in osmosis. 

4.-  4. It protects the cell from adverse environment.

Cell membrane

This is found in both animals and plants. All parts of the cell remain inside the membrane. It controls the substances that can pass through the cell. Semi-transduction has taken place, meaning only a few substances are allowed to pass through.

Mitochondria

It was discovered by a scientist named Altman

Here, s the krebs cycle going on Due to which ATP and glucose are distributed in the body and we get energy. Due to this, it is called the power house of the cell.

Endoplasmic reticulum

It provides internal support to the cell, hence it is called the internal skeleton of the cell. It is of two types.

1.-  Smooth E. R. -It produces carbohydrates and fats

2.- Rough E. R-  It produces proteins

Ribosome

It was discovered by a scientist named Pailade that this is the innermost organ of the cell, it manufactures proteins, hence it is a protein factory, it is of two types.

1.-  70.s ribosome- It is light and found in prokaryotic cells

2.-  80.s ribosome-   It is heavy and found in eukaryotic cells

 Golgibody

It was discovered by Camillo Golgi. It works to transport substances from one place to another. It is helpful in real transportatcells. 

Centrosome 

Boberi discovered this. This is helpful in the cell division that is found only in the brain. This is found only in the animal cell. The cell division in the plant cell is done through the cell plate.

Lysosome

It was discovered by a scientist named Dubey. It is inside the cell that the digestive enzyme is found. When any organ inside the cell does not work, it destroys that organ. When the cell is no longer working, it is cut. The entire cell is destroyed. This is what is called the bag of death. Lysosome is not found inside the RBC and after the RBC dies, it is found in the spleen due to which the spleen is called the tomb of RBC.

Nucleous

It was discovered by Robert Brown. It controls the cell, hence it is called the brain of the cell. 80% protein is found in it. 

Vacules

It stores water. It is found small in animals and large in plants.

Plastids

It was discovered by a scientist named Haeckel. It is of three types. 

1.-Chloroplast -It produces food. It is found in leaves and stems.

2.-leucoplast-It stores food. It is found in roots and fruits. 

3.-Cromoplast-It provides color, due to which the fruits have different colors.