The Working Cell

How Cells Get Energy

Life Depends on Energy What is energy? 1 st Law of Thermodynamics Two types of energy? 2 nd Law of Thermodynamics

2 nd Law in Action

Food Energy Calorie Energy needed to raise 1 g by 1 ºC Food is in kcal

Metabolism How can we get energy from foods we eat? Where is the potential energy in foods? How does the potential energy in foods get converted to kinetic energy useable by cells?

ATP: Adenosine triphosphate The tail of ATP is vary unstable This means greater potential energy When a phosphate is transferred to another molecule, energy is released

Energy Coupling Chemical energy is ‘harvested’ from food molecules Where’s the energy in food? This energy is used to recycle ADP to ATP

Enzymes Your metabolism and ETC are controlled and catalyzed by enzymes What are enzymes? How do they work?

Activation Energy For a reaction to occur, an energy barrier must be surmounted Enzymes make the energy barrier smaller

Induced-Fit Model Enzymes are substrate specific Substrates bind to active sites Substrates are altered slightly by induced fit Induced fit favors the reaction

How Enzymes Work

Enzyme Inhibition Some molecules affect enzyme function Competitive Non-competitive

Feedback Inhibition

Diffusion Molecules never stay still Diffusion moves molecules ‘down concentration gradient’

Osmosis Diffusion of water molecules

Osmoregulation

Passive & Facilitated Transport

Active Transport

Signal Transduction Pathway

Active Transport What about molecules that are too big to pass through a transport protein?

Endocytosis