The Cell: Structure and Functions

Introduction

The cell is the basic structural and functional unit of all living organisms. Some organisms are made of a single cell, while others such as humans are made of trillions of cells working together.

Types of Cells

• Prokaryotic cells have no true nucleus. Example: bacteria.
• Eukaryotic cells have a proper nucleus and membrane-bound organelles. Example: plant and animal cells.

Main Parts of the Cell

• Cell membrane: controls what enters and leaves the cell.
• Cytoplasm: jelly-like fluid where reactions take place.
• Nucleus: controls all cell activities and stores DNA.
• Mitochondria: the powerhouse of the cell, produces energy.
• Cell wall (plants only): gives shape and support.
• Chloroplast (plants only): carries out photosynthesis.

Key Points

• All living things are made of cells.
• Plant cells have a cell wall and chloroplasts; animal cells do not.
• The nucleus is the control centre of the cell.