Key Questions 1.What is passive transport? 2.What is active transport?
An important function of the cell membrane Control what enters and leaves the cell. Why would the cell control what enters and leaves the cell? Maintains homeostasis (balance)within the cell.
Diffusion – the why All particles are in constant motion. Particles move from areas of high concentration to areas of low concentration. Explain the process with this demonstration. Does this process require an input of energy? Diffusion is a type of passive transport (does not require energy).
Diffusion – the why PART 2 REMEMBER - The cell membrane is a lipid bilayer
Diffusion – the why PART 3 The membrane allows small, uncharged molecules to diffuse across it. Proteins in the cell membrane act as carriers for larger or charged molecules. Large Molecule Examples Charged Molecule Examples WaterIons – Cl -, H + Glucose
Passive transport -Types of diffusion Facilitated diffusion – molecules pass through protein channels. Osmosis – Diffusion of water.
Active transport Active transport is the movement of particles across the cell membrane from low concentration gradients to high concentration gradients using energy. Proteins in the membrane act as pumps to transport small molecules or ions. Large molecules are moved by vesicles in processes called exocytosis (out of cell) and endocytosis (into cell).