Structure and their functions

• phospholipid bilayer


  allows lipid-soluble molecules and small molecules such as water, oxygen and carbon dioxide to diffuse through
• Protein channel


  allows water-soluble molecules such as amino acids, ions (e.g. phosphate) and monosaccharides (e.g. glucose) through
• Cholesterol molecules


  located in between some phospholipid molecules to make the membrane more stable (e.g. in different temps)
• carbohydrate chain


  acts a recognition site for binding to other cells or chemicals such as hormones
• Phospholipid bilayer


  phosphate head - hydrophilic

  lipid tail - hydrophobic

  water-soluble molecules cannot pass through but lipid-soluble and small ones can