How do cells FUNCTION (work)? Cell Physiology How do cells FUNCTION (work)? STERNGRR Processes take place at the cellular level! Cell Transport Photosynthesis Cell Respiration

Cell Transport is a STERNGRR process • Lets food in for NUTRITION • Lets oxygen in for RESPIRATION • Lets waste out for EXCRETION Materials move in/out of cells through the cell membrane The cell membrane is SELECTIVELY PERMEABLE Phospholipid bilayer Membrane protein

Diffusion Demo BEFORE: Dialysis bag is “selectively permeable” Starch (large molecule) inside bag Iodine (small molecule) in beaker AFTER: Starch (large molecule) still inside bag; did NOT diffuse out Iodine (small molecule) diffused INTO bag – evidence is color change

Types of Cell Transport Passive Cell Transport Active cell transport Does NOT require energy Requires energy Movement DOWN the concentration gradient Movement AGAINST the High  Low Low  High

Molecules move until they reach EQUILIBRIUM: Diffusion Diffusion is a type of Passive Transport • Lets food in for NUTRITION • Lets oxygen in for RESPIRATION • Lets waste out for EXCRETION Movement of molecules from a high to low concentration Example: Oxygen is moved from a high concentration in the lungs, to a low concentration in the blood Molecules move until they reach EQUILIBRIUM: An equal concentration on both sides of the membrane

Molecules move until they reach EQUILIBRIUM: Osmosis Osmosis is a type of diffusion (a type of passive transport) Movement of WATER molecules from a high to low concentration Example: In salt water, there is more WATER in the cell than in the surrounding environment, so water leaves the cells and they shrivel Molecules move until they reach EQUILIBRIUM: An equal concentration on both sides of the membrane