Cell Structures (Edexcel IGCSE Science (Double Award)): Revision Note

Cell Structures

• Cells are surrounded by a cell membrane, which separates them from their external environment

• Inside the cell membrane is the cytoplasm, a jelly-like substance of water with dissolved substances

• Eukaryotic cells have organelles within the cytoplasm
  

  • Organelles are sub-cellular structures that carry out specific functions within the cell

• Within the cytoplasm of eukaryotic cells the following organelles are present:

  • Nucleus

  • Ribosomes

  • Mitochondria

    • Watch out for the difference between the terms 'mitochondria' and 'mitochondrion'

    • Mitochondrion is used to refer to one organelle

    • Mitochondria is used to refer to more than one organelle eg. muscle cells contain many mitochondria

• Plant cells contain the following additional structures: 

  • Cell wall

  • Chloroplasts

  • Permanent vacuole

When viewed under a microscope the structures inside a plant cell are visible. Some cellular structures, like ribosomes and mitochondria, are too small to be viewed under a light microscope but are visible under an electron microscope.

Cell Structures & Functions

Cellular Structures & Functions Table