1. Metabolism
Chapter 8
Review

2. Metabolism The totality of an organism’s chemical processes.
Concerned with managing the material and energy resources of the cell.

3. Catabolic Pathways
Pathways that break down complex molecules into smaller ones, releasing energy.
Example: Respiration

4. Anabolic Pathways
Pathways that consume energy, building complex molecules from smaller ones.
Example: Photosynthesis
Example: Putting amino acids together to make proteins

5. Energy Transformation
Governed by the Laws of Thermodynamics.

6. 1st Law of Thermodynamics
Energy can be transferred and transformed, but it cannot be created or destroyed.
Also known as the principle of “Conservation of Energy”

7. 2nd Law of Thermodynamics
Each energy transfer or transformation increases the entropy of the universe.

8. Entropy
Measure of disorder.

9. Summary
The quantity of energy in the universe is constant, but its quality is not.

10. Free Energy
The portion of a system's energy that can perform work.

11. Free Energy
G = H - TS G = free energy of a system H = total energy of a system T = temperature in oK S = entropy of a system

12. It has greater work capacity
Free Energy of a System
If the system has:
more free energy
it is less stable
It has greater work capacity

13. Spontaneous Process
If the system is unstable, it has a greater tendency to change spontaneously to a more stable state.
This change provides free (available) energy for work.

14. Free Energy Changes

15. Chemical Reactions Are the source of energy for living systems.
Are based on free energy changes.

16. Reaction Types
Exergonic: chemical reactions with a net release of free energy.
Endergonic: chemical reactions that absorb free energy from the surroundings.

17. Biological Examples Exergonic - respiration
Endergonic - photosynthesis

18. ATP Adenosine Triphosphate Made of: - Adenine (nitrogenous base)
- Ribose (pentose sugar)
- 3 phosphate groups

20. ATP
Works by energizing other molecules by transferring phosphate groups.

21. ATP vs Food ATP: Food: Renewable energy resource. Unstable bonds
Long term energy storage
Stable bonds

22. ATP Cycles Energy released from ATP drives anabolic reactions.
Energy from catabolic reactions “recharges” ATP.

23. ATP Cycle

24. ATP in Cells A cell's ATP content is recycled every minute.
Humans use close to their body weight in ATP daily.
No ATP production equals quick death.

25. Review – Metabolism What’s important:
The Laws of Thermodynamics govern metabolism
Role of ATP