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 1

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 2

Dialysis bag is “selectively permeable” Diffusion Demo BEFORE: Dialysis bag is “selectively permeable” Starch (large molecule) inside bag Iodine (small molecule) in beaker Diffusion Demo AFTER: Starch (large molecule) still inside bag; did NOT diffuse out Iodine (small molecule) diffused INTO bag – evidence is color change 3

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 4

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 5

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 6

Cell Energy Processes include: Photosynthesis and Cellular Respiration Photosynthesis is a STERNGRR process Cellular Respiration is a STERNGRR process The two processes work together in a cycle! 7

Involves making FOOD (sugar/glucose) for nutrition Photosynthesis Involves making FOOD (sugar/glucose) for nutrition CO2 + H2O + sun → C6H12O6 + O2 REACTANTS PRODUCTS Occurs in the CHLOROPLASTS of plant cells. Uses the green pigment CHLOROPHYLL to capture light energy Green light is reflected… all other wavelengths of light are absorbed by the plant. 8

What is going in and coming out of the plant? Photosynthesis What is going in and coming out of the plant? 9

They are 2 different things! ATP The food made in photosynthesis is used to make energy for cells! Food is NOT energy! They are 2 different things! Organisms (including plants) must use this food to produce energy Plants make food for all living organisms (sugar) ATP is the energy molecule for cells Adenosine P P P Energy is stored in a chemical bond – when the bond is broken, energy is released! Energy 10

Occurs in the Mitochondria of ALL cells Cellular Respiration Involves using food made in photosynthesis for respiration, to make ATP for energy. C6H12O6 + O2 → CO2 + H2O + ATP REACTANTS PRODUCTS Occurs in the Mitochondria of ALL cells 11

Cellular respiration can take place WITH Or WITHOUT Oxygen! Anaerobic respiration (fermentation) takes place when oxygen is NOT present Aerobic respiration occurs when oxygen is present Makes a LOT of ATP Makes a little ATP In plants and microorganisms: Alcoholic fermentation In animals: Lactic acid fermentation 12