Cell Membrane

• Function of glycocalyx

  Glycoproteins and glycolipids are involved in cell to cell recognition, this allows cells to recognise each other and group together to form tissues. Can act as antigens and receptor sites.
• Types of transport protein

  1. Channel proteins..span the membrane and create a hydrophilic channel that allows polar molecules through. Can be open or gated.2. Carrier proteins.. carry specific ions and molecules across the membrane. Can change shape to carry the substance from one side of the membrane to the other.

  
• Function of Proteins

  Provide stability as they anchor the phospholipid molecules.May act as enzymes.May act as adhesion sites..where adjacent cells are held together.Involved in cell recognition as receptors or antigens.Transport substances across the bilayer.

  
• Function of Cholesterol

  Increases membrane stability as restricts the sideways movemtn of phospholipid molecules.

  
• Function of Phospholipid bilayer


  Backbone of the cell membrane. Makes the membrane selectively permeable.

  
• Glycocalyx

  A layer of carbohydrate attached to the outer layer of the phospholipid bilayer.The polysaccharides are either bound to the phospholipids forming glycolipids or to the proteins forming glycoproteins.

  
• Why is the cell surface membrane described as the fluid mosiac model

  The phospholipids can flow sideways despite keeping the bilayer arrangement. the protein molecules float and are scattered between the phospholipid molecules like a mosaic.

  
• Position of cholesterol

  Between the phospholipid tails

  
• Proteins in cell surface membrane

  Scattered throughout.Extrinsic..attached to outside of bilayerIntinsic..embedded in one of the two layers of the bilayerTransmembrane.. extend across the bilayer.

  
• Phospholipid bilayer

  The phospholipids arrange themselves in a double layer. The hydrophobic tails turn away from the surrounding solution.The hydrophilic heads mix readily with the surrounding solution.

  
• Characteristics of phospholipids

  Hydrophilic heads that will mix with water but not lipid. Hydrophobic tails that will mix with lipid but not water.

  
• 2 Basic components of the cell surface membrane

  1. Phospholipid bilayer 2. Protein