What is a cell: Basic Structural and Functional Unit of living organisms

Unicellular Organisms: Organisms that are made up of one cell only

Multicellular Organisms: Organisms which are made up of more than one cell

Cells Vary in shapes. The variation in shape mainly depends on their function. Most cells (Except for Amoeba have a fixed shape):

• RBCs are circular and concave in order to absorb as much blood as possible and easy passage
• Nerve Cells are branched in order to conduct impulses from one point to another

Structure of a Cell

Cells are made up of multiple organelles. The most common ones are cell membrane, nucleus, and cytoplasm

Cell Membrane

• Delicate, Thin, elastic, and semi-permeable
• Maintains size and shape of the cell
• Protects internal contents of the cell
• Regulates entry and exit of substances in and out of cells
• Maintains homestasis

Cell Wall

• Only for Plant Cells