transport across cell membranes

• The cell membrane is selectively permeable.
• The cell membrane is made up of phospholipids and proteins.
• Molecules move across the cell membranes by diffusion, osmosis and active transport.
• Diffusion is when molecules move from a high concentration to a low concentration.
• Glucose, oxygen and amino acids move through diffusion.
• Passive transport requires no energy and moves down a concentration gradient.
• Osmosis is diffusion but with water.
• Active transport requires energy, moves up a concentration gradient.