Transport

Question 1

Phospholipid bilayer

Answer 1

• The phospholipid bilayer is made of phospholipids with hydrophilic/polar phosphate heads and non-polar/hydrophobic fatty acid tails
• This bilayer limits the movement of substances through the membrane so that only small non-polar molecules like oxygen can freely diffuse through
• Embedded in the membrane are transmembrane proteins that can act as carrier and channel proteins. Chanel proteins allow facilitated diffusion of ions, while carrier proteins can perform facilitated diffusion, they can also transport molecules across the membrane using energy from ATP in active transport
• Glycoproteins are embedded in the membrane and act as antigens for cell recognition, they also increase stability and adhesion of the cells
• Glycolipids are part of the membrane and increase stability and allow for adhesion of cells.
• Cholesterol is also found in the phospholipid bilayer and acts to increase rigidity