Cell – Class 10 Notes
Introduction
● The cell is called the basic structural and functional unit of life.
● All living organisms are made up of cells.
● Cells were first discovered by Robert Hooke in cork tissue in 1665.
● Antonie van Leeuwenhoek observed living cells for the first time.
Cell Theory
Cell theory was proposed by Matthias Schleiden and Theodor Schwann.
Main points:
1. All living organisms are made of cells.
2. Cell is the basic unit of life.
3. New cells arise from pre-existing cells.
Types of Organisms Based on Number of
Cells
1. Unicellular Organisms
● Made up of a single cell.
● Example: Amoeba, Paramecium.
2. Multicellular Organisms
● Made up of many cells.
● Example: Human beings, plants.
, Shape and Size of Cells
● Cells can have different shapes and sizes depending on their function.
● Examples:
○ Nerve cell → long and branched.
○ Red blood cell → circular and biconcave.
○ Muscle cell → spindle shaped.
Structure of a Cell
A cell mainly has three parts:
1. Cell Membrane
● Thin outer covering of the cell.
● Also called plasma membrane.
● Controls movement of substances in and out of the cell.
● It is selectively permeable.
2. Cytoplasm
● Jelly-like substance present inside the cell membrane.
● Contains cell organelles.
3. Nucleus
● Controls all activities of the cell.
● Contains hereditary material called DNA.
Parts of Nucleus
● Nuclear membrane
● Nucleoplasm
● Nucleolus
● Chromosomes
Introduction
● The cell is called the basic structural and functional unit of life.
● All living organisms are made up of cells.
● Cells were first discovered by Robert Hooke in cork tissue in 1665.
● Antonie van Leeuwenhoek observed living cells for the first time.
Cell Theory
Cell theory was proposed by Matthias Schleiden and Theodor Schwann.
Main points:
1. All living organisms are made of cells.
2. Cell is the basic unit of life.
3. New cells arise from pre-existing cells.
Types of Organisms Based on Number of
Cells
1. Unicellular Organisms
● Made up of a single cell.
● Example: Amoeba, Paramecium.
2. Multicellular Organisms
● Made up of many cells.
● Example: Human beings, plants.
, Shape and Size of Cells
● Cells can have different shapes and sizes depending on their function.
● Examples:
○ Nerve cell → long and branched.
○ Red blood cell → circular and biconcave.
○ Muscle cell → spindle shaped.
Structure of a Cell
A cell mainly has three parts:
1. Cell Membrane
● Thin outer covering of the cell.
● Also called plasma membrane.
● Controls movement of substances in and out of the cell.
● It is selectively permeable.
2. Cytoplasm
● Jelly-like substance present inside the cell membrane.
● Contains cell organelles.
3. Nucleus
● Controls all activities of the cell.
● Contains hereditary material called DNA.
Parts of Nucleus
● Nuclear membrane
● Nucleoplasm
● Nucleolus
● Chromosomes
