Fluid mosaic membranes

Need to know

What you need to know

• The membrane is 'fluid' because phospholipids and proteins can move laterally.
• It is a 'mosaic' because proteins are scattered throughout the bilayer like tiles.
• The phospholipid bilayer forms a barrier to water-soluble substances due to its hydrophobic core.
• Cholesterol in animal cells regulates fluidity, preventing the membrane from becoming too fluid at high temperatures or too rigid at low temperatures.
• Intrinsic proteins are embedded in the bilayer and can act as channels or carriers for transport.
• Extrinsic proteins are on the surface and can be enzymes or provide structural support.
• The glycocalyx (glycoproteins and glycolipids) is on the outer surface and is vital for cell recognition, adhesion, and as receptors.
• Membrane fluidity is increased by higher temperatures, shorter fatty acid tails, and a higher proportion of unsaturated fatty acid tails.

Explanation

Fluid mosaic membranes

1. The membrane is 'fluid' because phospholipids and proteins can move laterally.
2. It is a 'mosaic' because proteins are scattered throughout the bilayer like tiles.
3. The phospholipid bilayer forms a barrier to water-soluble substances due to its hydrophobic core.
4. Cholesterol in animal cells regulates fluidity, preventing the membrane from becoming too fluid at high temperatures or too rigid at low temperatures.