The Working Cell

How Cells Get Energy

Life Depends on Energy

What is energy?

1st Law of Thermodynamics

Two types of energy?

2nd Law of Thermodynamics

2nd Law in Action

Food EnergyCalorie 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 surmountedEnzymes make the energy barrier smaller

Induced-Fit Model

Enzymes are substrate specificSubstrates bind to active sitesSubstrates are altered slightly by induced fitInduced fit favors the reaction

How Enzymes Work

Enzyme InhibitionSome 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

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