Cell

All living things are made up of cell. The very simple animals and plants (Paramecium, Amoeba and yeast) are just single cells. These cells are capable of carrying out all the functions of a living organisms like movement, respiration, digestion and so on.

Simple organisms are made up of rows of cells called filaments, while others are just groups of cells. Cells are very small in size and so, they cannot be seen with naked eyes. They can be seen only with the help of microscope.

The cell is defined as a structural and functional unit of living organisms. Cells unite together to form tissues. Some plants and animals are made as single cell only, hence they are called unicellular. On the other hand, animals and plants having a large number of cells in their bodies are called as multicellular.

The cells are broadly classified into two types: prokaryotic cells and eukaryotic cells.

Prokaryotic cells do not have well organized nucleus. Their nuclear material is not enclosed in a nuclear membrane. They lack several cell organelles like mitochondria, endoplasmic reticulum, nucleolus etc.

Eukaryotic cells have a well organised nucleus. They are larger than prokaryotic cells. Their nuclear material is enclosed in a nuclear membrane.

Things to remember

• The cell is defined as a structural functional unit of living organisms. Cells unite together to form tissues. Some plants and animals are made as single cell only, hence they are called unicellular. On the other hand, animals and plants having a large number of cells in their bodies are called as multicellular.
• Plant cell:
• A typical plant cell consists of the rectangular shape and following structures are described below:
• Cell wall
• Cell membrane
• Cytoplasm
• Vacuole
• Nucleus
• Plastid
• Animal Cell:
• The structure of animal cell is almost the round in all the animals. The structure of an animal cell consists following structures.

• It includes every relationship which established among the people.
• There can be more than one community in a society. Community smaller than society.
• It is a network of social relationships which cannot see or touched.
• common interests and common objectives are not necessary for society.

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