THE CELL SURFACE MEMBRANE CONSISTS OF:
• Phospholipid bilayer (all the molecules are arranged so that the hydrophobic tails are inside the bilayer)
• proteins
• cholesterol
• glycoproteins (protein molecules with polysaccharides attached)
• glycolipids (lipid molecules with polysaccharides attached)
• Channel proteins
WHY IS IT CALLED THE FLUID MOSAIC MODEL?
The plasma membrane is described to be fluid because of the lipids and membrane proteins that can move freely.
The membrane is called mosaic because like a mosaic that is made up of many different parts so is the plasma membrane
PHOSPHOLIPID BILAYER:
• The cell surface membrane consists of a bilayer that contains two layers of phospholipids.
• In a phospholipid there are two fatty acids and a negatively charged phosphate group.
• the phosphate head of the molecule is polar one end is slightly positive and the other negative
• so, this makes the phosphate head attract other polar molecules like water, so it is hydrophilic
• fatty acid tails are non-polar, so they are hydrophobic Cells are filled with watery cytoplasm and are surrounded by aqueous tissue fluid. so, the phospholipids form a bilayer. This stops the hydrophobic fatty acids tails from being in contact with the water on both sides of the membrane and ensures that the hydrophilic phosphate heads are in contact with the water.