Introduction to Metabolism

1. Introduction to Metabolism Chapter 6

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

5. Energy • Ability to do work. • The ability to rearrange a collection of matter. • Forms of energy: • Kinetic • Potential • Activation

6. Kinetic Energy • Energy of action or motion.

7. Potential Energy • Stored energy or the capacity to do work.

8. Activation Energy • Energy needed to convert potential energy into kinetic energy. Activation Energy Potential Energy

9. Energy Transformation • Governed by the Laws of Thermodynamics.

10. 1st Law of Thermodynamics • Energy can be transferred and transformed, but it cannot be created or destroyed. • Also known as the law of Conservation of Energy.

11. 2nd Law of Thermodynamics • Each energy transfer or transformation increases the entropy of the universe.

12. Entropy • Measure of disorder.

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

14. Question? • How do living organisms overcome Entropy? • By using energy from the environment or external sources (e.g. food, light).

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

16. 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

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

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

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

20. Exergonic/Endergonic

21. Biological Examples • Exergonic - respiration • Endergonic - photosynthesis

22. Cell - Types of Work • Mechanical - muscle contractions • Transport - pumping across membranes • Chemical - making polymers

23. Cells use ATP as their energy source • Adenosine Triphosphate • Made of: - Adenine (nitrogenous base) - Ribose (pentose sugar) - 3 phosphate groups

25. Adenine Phosphates Ribose

26. Key to ATP • Is in the high energy bonds between the three phosphate groups. • Negative charges on the phosphate groups repel each other and makes the phosphates unstable.

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

28. ATP CycleATP ADP + P + Energy

29. 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.

30. Redox reactions

31. Oxidation - definitions • Loss of electrons. • Loss of energy. • Loss of Hydrogens from Carbons.

32. Reduction - definitions • Gain of electrons. • Gain of energy. • Gain of Hydrogens to Carbons. Comment - be careful not to use “reduction” in lay terms.

33. Redox reactions • Reactions are usually paired or linked together. • Many of the reactions will be done by phosphorylation.

34. Phosphorylation • Adding a phosphate group to a molecule. • The phosphate group adds “energy” to the molecule for chemical reactions.

35. ATP • ATP energizes other molecules by transferring phosphate groups to them….. The process is called phosphorylation.

36. Phosphorylation