1. Living Metabolism Part 1
AP Biology
Living Metabolism
Part 1

2. Energy and Life
Life requires energy to survive. The way that different organisms acquire this energy and use it to survive allows for diversity.
In this unit we will look at energy, how energy is used by living organisms, and two processes that are fundamental to life.

3. Catabolism (Hydrolysis Reaction)
Reactants
Amount of
energy
released
(G < 0)
Free energy
Energy
Products
Progress of the reaction
Exergonic reaction: energy released

4. Catabolism - Exergonic
Catabolism refers to the breaking down (hydrolysis) of a molecule.
This process releases potential E stored in the chemical bonds of the molecule.
This is an exergonic reaction, because heat is released into the environment.
Cellular respiration is an example of a natural catabolic reaction.

5. Anabolism (Dehydration Synthesis)
Products
Amount of
energy
required
(G > 0)
Free energy
Energy
Reactants
Progress of the reaction
Endergonic reaction: energy required

6. Anabolism - Endergonic
Anabolism refers to the assembly (dehydration synthesis) of molecules.
This requires kinetic E to position monomers in a way that chemical bonds can be formed.
This is an endergonic reaction, because energy is absorbed from the environment.
Photosynthesis is an example of a natural anabolic reaction.

7. Energy Coupling Two processes united by Energy
THIS IS THE BIG PICTURE IDEA OF THIS WHOLE UNIT!!
The processes of cellular respiration and photosynthesis are “coupled” by energy. One process uses light energy to create organic molecules, and the other process breaks those organic molecules down to release energy.
These processes need one another to continue. It is a fantastic cycle that drives all life on Earth.
Life requires free energy to survive. But, what is free energy?

8. Catabolism (Hydrolysis Reaction)
Reactants
Amount of
energy
released
(G < 0)
Free energy
Energy
Products
Progress of the reaction
Exergonic reaction: energy released

9. Anabolism (Dehydration Synthesis)
Products
Amount of
energy
required
(G > 0)
Free energy
Energy
Reactants
Progress of the reaction
Endergonic reaction: energy required

10. Bioenergetics Video Link

11. Free Energy – “Gibb’s”
Gibb’s free energy is the energy that is available in a system to do work.
Energy that is available to make ATP.
ATP is used for the signal transduction pathway, moving materials around within the cell, moving materials across the membrane, and anabolic/catabolic reactions.
The change is the free energy, determined by using the formula on the next slide, will be positive or negative, depending on the type of reaction.

12. Gibbs “Free” Energy Δ G = ΔH – TΔ S G- Gibbs “free” energy
H – Enthalpy (Total usable energy in the system)
T – Temperature in Kelvin (273 + C⁰)
S- Entropy (Disorder created by something being broken down)
Δ – Change in a variable over time
****Overall, the change in free energy is the final energy minus the initial energy in the system.****

13. Free Energy
Not all energy is available as a result of a reaction! Much of the energy is lost as heat.
However:
If the Δ G is negative, then there is energy available to do work.
This is the result of cellular respiration. (Catabolic, Exergonic)
If the Δ G is positive, then there is energy that is not available. It is in the chemical bonds.
This is the result of photosynthesis. (Anabolic, Endergonic)

14. Practice Problems
Calculate the Gibbs free energy change (Δ G ) for the following chemical reaction:
ATP  ADP + Pi
The reaction occurs at 68 °C, the change in heat (Δ H) = 19,070 cal, and the change in entropy (Δ S) = 90 cal/K.
Is the reaction anabolic or catabolic? Endergonic or exergonic?

15. 68 °C = 341 K, therefore the equation is set up in the following way:
Δ G = Δ H – T Δ S
Δ G = 19,070 cal – (341 K) (90 cal/K)
Δ G = –11,620 cal = –11.62 kcal

16. Practice Problems
Calculate the Gibbs free energy change (Δ G) for the following chemical reaction:
glutamate + NH3  glutamine + H2O
The reaction occurs at 68 °C, the change in heat (Δ H) = 4103 cal, and the change in entropy (Δ S) = 2.4 cal/K.
Is the reaction anabolic or catabolic? Endergonic or exergonic?

17. 68 °C = 341 K, therefore the equation is set up in the following way:
Δ G = Δ H – T Δ S
Δ G = 4103 cal – 341 K (2.4 cal/ K)
Δ G = cal = 3.3 kcal

18. Unstable (Capable of work) vs. Stable (no work)
G < 0
G = 0
A closed hydroelectric system

19. Progress of the reaction
LE 8-6a
Reactants
Amount of
energy
released
(G < 0)
Free energy
Energy
Products
Progress of the reaction
Exergonic reaction: energy released

20. Progress of the reaction
LE 8-6b
Products
Amount of
energy
required
(G > 0)
Free energy
Energy
Reactants
Progress of the reaction
Endergonic reaction: energy required

21. Potential Energy vs. Kinetic Energy

22. Types of work performed by living cells
Motor protein
Protein moved
Mechanical work: ATP phosphorylates motor proteins
Membrane
protein
ADP
ATP + P i P P i
Solute
Solute transported
Transport work: ATP phosphorylates transport proteins P
NH2 +
NH3
Glu + P i
Glu
Reactants: Glutamic acid
and ammonia
Product (glutamine)
made
Chemical work: ATP phosphorylates key reactants

23. ATP

24. Phosphorylation