The Fundamental Unit of Life

In the plant cell, an additional layer of covering is found over the plasma membrane, called Cell Wall. The Cell Wall provides rigidity and structural strength to the plants.

The cell wall is made up of cellulose.

It is the cell wall that enables the cells of plants, fungi, and bacteria to withstand very dilute solutions without bursting.

While losing water through osmosis, the shrinkage of the contents of cells of living plants takes place away from the cell wall.

Hypotonic Solution And Hypertonic Solution

The solution having a lower concentration of the solutes than another solution is known as Hypotonic solution.

The solution having a higher concentration of the solutes than another solution is known as Hypertonic solution.

Plasmolysis And Cytolysis

Plasmolysis

This phenomenon of shrinkage or contraction of living plant cells by losing water due to the presence of concentrated solution in the external environment (media) is known as Plasmolysis.

In plasmolysis, the shrinkage of the content of the cell takes place away from the cell wall.

Deplasmolysis (Cytolysis)

Swelling of plant cells by the gain of water due to the presence of dilute solution in the external environment is called Cylolysis. Cytolysis is known as Deplasmolysis also.

Deplasmolysis or Cytolysis is the reverse process of Plasmolysis.

This is the cell wall that permits cells of plants, fungi, and bacteria to withstand hypotonic solution (dilute solution) without burstings.

In this case, the cell build pressure on the cell wall, and the cell wall exerts equal pressure against the swollen cell.

Water molecules go in and out of the cell through the plasma membrane through the process of osmosis.

It is the cell wall that enables the cells of plants, fungi, and bacteria to withstand much greater changes in the surroundings than animal cells, which do not have cell walls in their cells.

Nucleus

Nucleus or Cell Nucleus is a membrane bound cell organelle present in a eukaryotic cell. The nucleus is not found in bacteria and blue-green algae.

The Structure of the Nucleus or Cell Nucleus

The Nucleus is covered with a double layered membrane. This double layer of the nucleus is called Nuclear Envelope or Nuclear Membrane. This double layered membrane of the cell nucleus is made up of lipids and proteins.

The nucleus of a cell contains chromosomes which contain genetic information in the form of genes. And hence the cell nucleus plays important role in the gene transfer from the parent to the next generation and structural and constructing and organising information of cells.

The liquid content found in the nucleus is called Nucleoplasm.

Chromosomes

The DNA is packed into thread like structures in the nucleus of animal and plant cells and is known as Chromosomes. Chromosomes are composed of DNA and protein.

The DNA stands for "Deoxyribo Nucleic Acid". The protein in the DNA is called Histones.

The DNA molecules contain the necessary information for constructing and organising cells.

Chromosomes are visible in the cell nucleus only during cell division or when a cell is about to divide. During cell division, the chromosomes are visible as rod-shaped structures.

When a cell Is not dividing, the chromosomes are present as chromatin. Chromatin material is an entangled mass of thread like structure. While dividing the cell, the chromatin materials get organised into chromosomes.

Function of the Cell Nucleus

The Nuclear Membrane keeps the cell nuclear separate from its external environment. This membrane has pores that allow the passing of substances within a cell.

The Nucleus keeps genetic information in it. The nucleus controls and regulates the activities of the cell. The nucleus is the command center of a cell.

Types of the cell on the basis of Cell Nucleus

On the basis of the cell nucleus the organisms can be divided into two types, eukaryotes and prokaryotes.

Eukaryotes

Organisms that have a membrane bound nucleus in their cells are known as Eukaryotes. And such cells are known as Eukaryotic Cells. Animals and other multicellular organisms along with some unicellular organisms have Eukaryotic Cells, and such organisms are known as Eukaryotes. They belong to a group of organisms known as Eukaryota or Eukarya.

Prokaryotes

Unicellular organisms having lack nucleus and other membrane bound organelles are known as Prokaryotes, for example, bacteria and archaea.

In the word "Prokaryotes" is the combination of two words "Pro + Karyote". The "pro" stands for "primitive or primary", and "Karyote" means "Nucleus".

This means prokaryotes are the first organisms come on the earth.

In Prokaryotic cells many of the functions are performed by the poorly organised parts of the cytoplasm.

Cytoplasm

Cytoplasm is the fluid content inside the plasma membrane of a cell. The cytoplasm is a dense liquid content and helps cell organelles to perform their work.