1. An Introduction to Metabolism

2. Metabolism/Bioenergetics
Metabolism: The totality of an organism’s chemical processes.
Catabolic pathways: degradative process
cellular respiration
releases energy
Anabolic pathways: building process
Protein synthesis
Photosynthesis
Consumes energy

3. Anabolic
Catabolic

4. Energy Coupling in Metabolism
Catabolic Reactions provide the energy that drives Anabolic Reactions forward
Catabolic reaction
Anabolic reaction

5. Ying & Yang of Metabolism
Metabolism = Anabolism + Catabolism
Photosynthesis requires Respiration
Respiration requires Photosynthesis
Energy Production = Energy Consumption

6. Thermodynamics Thermodynamics ~ study of Energy (E) transformations
Energy (E)~ capacity to do work
Kinetic energy~ energy of motion
Potential energy~ stored energy

7. Potential Energy “Kinetic” Kinetic Energy Waste Heat (once reaches
Gravity (center Earth)
Waste Heat
(once reaches
Bottom)

8. Laws of Thermodynamics
1st Law: conservation of energy
not created / destroyed
E transferred / transformed
(e.g., chemically stored energy transformed to heat)
2nd Law: Efficiencies of energy transformation never equal 100%
transformations increase entropy (disorder, randomness)
Energy is lost between transfers typically as heat
Not reversible unless the system is open & the lost energy is resupplied from the environment

9. Chemical Energy:
E is stored in the bonds of the chemical they are holding together.
Enthalpy : The total potential energy of a molecule.
exothermic reactions enthalpy of products less than reactants
feel the heat
endothermic reactions products have more enthalpy than reactants
heat is added
Energy added to get started is activation energy.

10. Free energy
Free energy: portion of system’s E that can perform work (at a constant T)
Exergonic reaction: net release of free E to surroundings
Spontaneous
Endergonic reaction: absorbs free E from surrounding
Non-Spontaneous

11. ATP the work horse of the cell
Adenosine triphosphate (ATP)
3 main types of work.
Mechanical (cell movement)
Chemical (anabolism)
Transport (materials into and out of the cell)
An adenine attached to a ribose sugar attached to 3 phosphates.
Essentially an RNA nucleotide

12. Energy Coupling
E coupling: use of exergonic process to drive an endergonic one
Redox reactions
ATP tail: high negative charge
ATP hydrolysis: release of free E
ATP + H2O  ADP + P
▲G = -7.3 kcal / mol
Phosphorylation: increases energy
ADP + P  ATP
▲G = kcal / mol

13. Energy for Anabolism