Sample: Cell Ultrastructure



Ultrastructure of Cells – Refers to the fine,detailed structure of cells as seen under the electron microscope.

In this topic we will be looking at the plasma membrane as referred to in the topic “Cell Structure and Function” in detail.

The Animal Cell viewed under the Light Microscope.

The Plasma Membrane is composed of 2 Components.

  1. Phospholipids
  2. Proteins


The Model for Membrane Structure: Composed of a lipid with a phosphate molecule attached


Outside Cell

Inside Cell


Why is the plasma membrane arranged in this way?

The phosphate head of the phospholipid is hydrophobic, meaning it “likes” water, while the lipid attached to the phospholipid is hydrophilic, meaning it “dislikes” water.

Therefore the phospholipids are arranged with the phosphate ends facing outwards and the lipid ends facing inwards.

The proteins float on the surface of the membrane.



  • Cytoplasm around mitochondria is called cytosol
  • Function – Chemistry of respiration



  • Function – Chemistry of photosynthesis