Come nd explore the depth of knowledge with me. In this class we will cover cell , different organalles present in cytoplasm, why the cell is fundamental unit , u will be able to visualise concepts in mind actually what is going on inside cell and how it is maintaining the essential body functons. 

Introduction

• The fundamental unit of life is cell.

• Cell was first discovered by Robert Hooke in 1665 in a simple microscope.

• In 1674, Leeuwenhoek, with the help of developed microscope, discovered the free living cells in pond water.

• In 1831, Robert Brown had discovered the nucleus in the cell.

• In 1839, Purkinje used the term ‘protoplasm’ for the fluid substance found in the cell.

• The cell theory was proposed by Schleiden (1838) and Schwann (1839).

• According to the cell theory, all the plants and animals are composed of cells and that the cell is the basic unit of life.

• In 1855, Virchow further expanded the cell theory and suggested that all cells arise from pre-existing cells.

• In 1940, the discovery of electron microscope made possible to observe and understand the complex structure of the cell.

Unicellular Organisms

• The single cellular organisms, such as Amoeba, Chlamydomonas, Paramoecium, and bacteria, are known as unicellular organisms.

Multicellular Organisms

• The organisms consisting of many cells are known as multicellular organisms. E.g. human being, animals, birds, etc.

Significant Characteristics of Cells

• Each living cell has the aptitude to perform certain basic functions that are characteristic of all living forms.

• Each such cell has certain specific components within it known as cell organelles.

• Different types of cells have different function and each cell organelle performs a special function.

• These organelles collectively constitute the basic unit of life known as cell.

• All cells are found to have the same organelles, irrespective of their different functions and the organism they found in.

Structural Organization of Cell

• Following are the three basic features that every cell possesses −

  • Plasma Membrane/Cell Membrane

  • Nucleus

  • Cytoplasm