CB2 Memebrane

• Phospholipids & proteins are the two main components of a membrane
• The cell membrane is selectively permeable, allowing only some molecules to cross it
• Passive transport is movement across a cell membrane that requires no energy from the cell
• Osmosis & diffusion are examples of passive transport
• Diffusion is the movement of molecules down a concentration gradient from an area of higher to an area of lower concentration
• Examples of diffusion include glucose moving from the blood to the cells for respiration, and oxygen moving from the lungs to the blood
• Osmosis is the movement of water molecules from an area of higher water concentration to an area of lower water concentration, across a selectively permeable membrane
• Effect of being placed in a solution of higher water concentration on animal cells is burst
• Effect of being placed in a solution of lower water concentration on animal cells is shrink
• Effect of being placed in a solution of higher water concentration on plant cells is turgid
• Effect of being placed in a solution of lower water concentration on plant cells is plasmolysed
• Active transport is the movement of molecules and ions from an area of low concentration to an area of high concentration, against a concentration gradient
• Energy is required by membrane proteins for active transport