1. Metabolism: Energy and Enzymes

2. Energy Ability to do work, change matter Kinetic – energy in motion
Potential – stored energy
Chemical energy (food)
Mechanical energy (motion)

3. Thermodynamics
2 Laws:
1. Law of conservation of energy – Energy cannot be created or destroyed, but it can be changed from one form to another (heat energy)
2. Energy cannot be changed from one form to another without a loss of usable energy.
When heat is released, it is not longer available to do work, lost to the environment.
Cells are 40% efficient, rest of energy is given off as heat

4. Entropy
Used to indicate the relative amount of disorganization in universe
Every process that occurs in cells increases the total entropy of the universe.
More organized = less stable
Clean room, more organized but less stable than a messy room
entropy clip

5. Metabolic reactions Metabolism Reactants – products
Free energy – amount of available energy to do work after a chemical reaction has taken place (G)
Exergonic reactions – delta G is negative, products have less energy than the reactants, reaction is spontaneous, energy is released, ex. ATP breakdown
Endergonic reactions – delta G is positive and products have more free energy than the reactants. Can only take place if there is an input of energy.

6. Adenosine Triphosphate
Energy currency, universal, can be used in many different types of reactions.
Composed of Adenine (nitrogen base), ribose sugar and 3 phosphate groups
Uses of ATP
Chemical work – synthesize macromolecules
Transport work – pumps
Mechanical work – muscle contraction, cilia to beat, chromosomes to move.

7. Coupling reactions
Energy released by exergonic reactions drive endergonic reactions.
ATP breakdown is exergonic

8. Function of ATP Chemical work – helps to synthesize macromolecules
Transport work – supplies energy for pumps across membrane
Mechanical work – supplies energy to do work, muscle contraction, cilia beat…

9. Chemical reactions Reactants  products Absorb or release energy
Bonds broken and new ones formed
CO2 + H2O + light  C6H12O6 + O2
Absorb or release energy
Water freezing – energy released
Ice melting – energy absorbed
metabolism

10. Enzyme activity Activation energy is used to start chemical reactions
Biochemical reactions – reactions in cells
Enzyme – increase speed of chemical rxn
Catalyst – reduce activation energy of chem. Rxn
Homeostasis
Most are proteins
End in -ase
Different enzymes catalyze different chemical reactions ex. Lactase/lactose

11. Degradative reactions – substrate broken down
Synthesis reaction – substrates combine, larger product
Enzymes are not used up in the reaction, available to bind to another substrate.
Active site – area on enzyme that the substrate binds to.
Induced fit model- enzyme complex undergoes a slight change in shape

12. Enzyme substrate complex

13. Factors that affect enzyme activity
Temperature pH
Can change shape of enzyme – denaturing
If enzyme changes, chemical reaction can not take place
Cofactors – non protein helpers
Inorganic - Zinc, iron, copper
Organic – called a coenzyme, vitamins

14. Enzyme inhibitors
Competitive inhibitors – mimic substrates and compete for active site, reduce productivity
Noncompetitive inhibitors – do not bind to active site, but the allosteric site
When bound, changes shape of active site
Toxins and poisons