Cell: Revision

Hello Dear Students,

I have just summarized a part of the chapter for you. These are the basic points which you all must know.

Do wait for the next part of the chapter where we will revise the cell organelles and their functions.

Cell: The Structure and Functions

Summary

v A cell can be defined as the basic structural and functional unit of all living things.

v First discovered by Antonie Van Leeuwenhoek. He developed a simple microscope using only a biconvex lens. He was the first to see the blood cells of frog and recognized them as living units of all living beings. . He did not call them cells.

v Robert Hooke was the first to coin the term “cell”.

v The branch of biology which deals with the study of cells is called cytology.

v Protoplasm is the living substance of the cell. Cytoplasm + nucleus.

v On the basis of number of cells, the organisms can be of two types:

1. Unicellular: Organisms formed of only one cell. Example: Amoeba, Paramecium, Yeast, Bacteria, Chlamydomonas.

2. Multicellular: Organism made up of millions and billions of cells. Example: Human beings, Mango, Rose, Tiger, Etc.

v Cell Shape:

¨ Spherical: Red blood cell.

¨ Oval: Chlamydomonas

¨ Cylindrical: Spirogyra

¨ Amoeboid: Amoeba

¨ Cubical/ rectangle: Cells of Leaf

¨ Slipper-shaped: Paramecium

¨ Spindle-shaped: Smooth muscles.

v Cell Size:

§ Smallest cell: Bacteria

§ Longest cell: Nerve cell

§ Largest cell: Ostrich egg

v Cell Theory:

Formulated by Schleiden, Schwann and Virchow.

§ Every living cell is made up of one or many cells.

§ The cell is the structural unit of all living organisms.

§ The cell is the functional unit of all living organisms.

§ All cells arise from the pre-existing cells.