1. Energy Transformations
Metabolism
Energy Transformations

2. Metabolism The capacity to acquire & use energy to ensure survival.
Cellular activities, Maintenance, Growth
Building & Accumulating
Breaking Apart & Eliminating
Involves…
ENERGY
CHEMICAL REACTIONS

3. ENERGY The ability to do “work”…to cause change. Variety of forms:
Light, Heat, Mechanical, Chemical, Electrical
2 Main States:
POTENTIAL
Stored energy, with the potential to do something.
KINETIC
Energy of motion; in the process of doing something.

4. Energy Transformations
Potential Kinetic Potential Kinetic…
Governed by Laws of Thermodynamics.
1st Law of Thermodynamics
(Conservation of Energy)
2nd Law of Thermodynamics
(Entropy)

5. 1st Law of Thermodynamics
Energy is neither created nor destroyed.
The amount of energy in the universe is constant.
BUT, energy can change FORMS
SUN
STARCH
FOOD
MOVEMENT
COAL
ELECTRIC
HEAT

6. 2nd Law of Thermodynamics
Energy is generally transformed from HIGH QUALITY to LOW QUALITY forms.
This leads to less and less organization.
Entropy is a measure of disorganization.
SUN
STARCH
FOOD
MOVEMENT
COAL
ELECTRIC
HEAT

7. Life has Organization Opposite of Entropy, but How? Why?
Life requires a constant re-supply of high quality energy from…the sun.

8. Organization requires Energy
Energy is stored (by living things) in chemical form…in chemical bonds.
When bonds are broken, energy is often liberated.
Chemical Reactions!
Loss of energy…
Gain of energy…
EXERGONIC
ENDERGONIC

9. Chemical Reactions Endergonic Exergonic Reversible Coupled A + B C
C A + B
A + B C
E F + G
A + B C

10. Metabolic Pathways SERIES of chemical reactions.
Biosynthetic (Anabolic) = building pathways which consume energy.
Degradative (Catabolic) = degrading pathways which release energy.
Enzymes are responsible for each reaction.
(we’ll come back to these later)

11. ATP
Adenosine Triphosphate
Energy Carrier – the energy currency

12. ATP Photosynthesis Cellular Respiration Sunlight Chemical Energy ATP
-Chemical Energy Work

13. ATP Hydrolysis
ATP ADP + Pi

14. ATP
Drives other endergonic reactions:
ATP ADP + Pi
A + B C

15. ATP
Regeneration of ATP = Phosphorylation.

16. ATP Phosphorylation ATP is “primed”. ?
1. Substrate-Level Phosphorylation.
2. Chemiosmotic Phosphorylation. ?
ADP + Pi ATP

17. The CONTROLLERS of Energy Transformations
Enzymes
The CONTROLLERS of Energy Transformations

18. Remember Metabolism…
The capacity to acquire & use energy to ensure survival.
Cellular activities, Maintenance, Growth
Building & Accumulating
Breaking Apart & Eliminating
Involves…
ENERGY
CHEMICAL REACTIONS
Controlled by
ENZYMES

19. Enyzmes Proteins that catalyze chemical reactions
Speed up reactions (“Catalysts”).
Do not become part of the products.
Enzymes act on substrates (the specific reactants for a chemical reaction)
Enzymes are substrate-specific.
There are many many enzymes!

20. Enyzmes
Active Site – a region (or regions) where the substrate(s) fit.

21. Enyzmes Induced-fit model of enzyme activity.
Enzyme induces the fit of substrates by bringing them into closer proximity & orientation.

22. Enyzmes
Enzymes lower the Activation Energy for a particular chemical reaction.

23. Enyzmes
Enzymes function best within certain Temperature & pH ranges.

24. Control of Enzymes
Inducers - molecules that act as “ON” switches (Activators)
Substrates
Cofactors (non-protein portions of an enzyme)
Metal ions (Fe++)
Coenzymes (large organic cofactors)
Vitamins
NAD NADH
Allow proper enzyme conformation, turning them “ON”.

25. Control of Enzymes
Inhibitors (molecules that attach to enzymes, turning them “OFF”)
Competitive Inhibitors
Active Site inhibitors (“blockers”)
Non-competitive Inhibitors
Allosteric inhibitors
Feedback Inhibition
The product of a metabolic pathway inhibits an enzymes responsible for catalyzing a reaction earlier in the pathway.

26. Feedback Inhibition