2. Standard States for Free-Energy Changes
for pure solids and liquids, _____________________
for gases, the gas at _____________________
for solutions, a concentration __________________
For the reaction
We can rewrite the equation that relates the G for the reaction under any conditions to the free-energy change under standard conditions (G˚)

3. Standard States for Free-Energy Changes (Cont’d)
When the reaction is at equilibrium, G = _____
• If we can determine the concentration of reactants and products at equilibrium, we can determine Keq and, from it, the change in free energy for conversion of one mole of reactant to product(s)

4. Modified Standard State for Biochemical Rxns
Standard free energy change, G°, assumes a molar concentration of 1 M
if [H+] = 1 M, then pH = _____
but the pH in most cells is near the neutral range
For biochemical reactions, we define a different standard state for the concentration of H+
standard state for [H+] = _____________________
this modified standard state is given the symbol _____
Summary
The usual thermodynamic standard state implies that the system involved is at pH=0, which is seldom, if ever, found in living things. The modified standard state explicitly states that the system is at pH=7

5. Biochemical Connections: Thermodynamics

6. The Nature of Metabolism
_____________: the chemical rxns of biomolecules
Metabolism is the biochemical basis of
_____________: the breakdown of larger molecules into smaller ones; an oxidative process that releases energy
_____________: the synthesis of larger molecules from smaller ones; a reductive process that requires energy

7. A Comparison of Catabolism and Anabolism
• Metabolism is the sum total of the biochemical reactions in an organism

8. The Role of Oxidation and Reduction in Metabolism
Oxidation-Reduction reactions are those in which electrons are transferred from a donor to an acceptor
________: the loss of electrons; the substance that loses the electrons is called a ________ agent
________: the gain of electrons; the substance that gains the electrons is called an ________ agent
Carbon in most reduced form- ___________
Carbon in most oxidized form- ___________ (final product of catabolism

9. Summary
In ________, large molecules are broken down to smaller products, releasing energy and transferring electrons to acceptor molecules of various sorts. The overall process is one of oxidation.
In ________, small molecules react to give rise to larger ones; this process requires energy and involves acceptance of electrons from a variety of donors. The overall process is one of reduction

10. Coenzymes used in Biologically important Redox Rxns
Conversion of ethanol to acetaldehyde is a two-electron oxidation

11. NAD+/NADH: An Important Coenzyme
Nicotinamide adenine dinucleotide (NAD+) is an important coenzyme
Acts as a biological oxidizing agent
The structure of NADH is comprised of a nicotinamide moiety. It is involved in the reaction. It is a derivative of nicotinic acid
NAD+ is a two-electron oxidizing agent, and is reduced to NADH

12. Structures & Redox States of Nicotinamide Coenzymes

13. FAD/FADH2
Flavin adenine dinucleotide (FAD) is also a biological ______________ agent
Protons and electrons are accepted by FAD

14. The Structures of Riboflavin, Flavin Mononucleotide (FMN), and Flavin Dinucleotide (FAD)

15. Coupling of Production and Use of Energy
The coupling of ________-____________ and ________-____________ reactions is a central theme in the metabolism of all organisms
Energy cannot be used directly, must by shuttled into easily accessible forms of chemical energy
“High Energy” bonds require or release convenient amounts of energy, depending on the direction of the reaction
______ is an essential high energy bond-containing compound
Phosphorylation of ADP to ATP _________ energy
Hydrolysis of ATP to ADP _________ energy

16. The Phosphoric Anhydride Bonds in ATP
“High Energy” Bonds are in red

17. ATP
Four – charges on ATP and 3 on ADP, therefore ATP is ______________ ______________ .
Why is ATP less stable, charge-wise, than ADP?
Energy must be expended to put an additional ___________________________________________
Also, entropy loss when ADP is phosphorylated because there is a potential loss of ______________ ______________ of inorganic phosphate (Pi) on phosphorylation of ADP to ATP

18. Loss of a Resonance-Stabilized Phosphate Ion
…in Production of ATP

19. ATP Hydrolysis Decreases Electrostatic Repulsion
Marked decrease in ________________ _______________ of -phosphate of GDP upon hydrolysis of ATP to ADP

20. Role of ATP as Energy Currency

21. Summary Hydrolysis of ATP to ADP releases energy
In the coupling of biochemical reactions, the energy released by one reaction, such as ATP hydrolysis, provides energy for another

22. CoA in Activation of Metabolic Pathways
A step frequently encountered in metabolism is activation
activation: the formation of a ___________________ substance
A metabolite is bonded to some other molecule and the free-energy change for breaking the new bond is ______________ .
Causes next reaction to be ______________

23. Two Ways of Looking at Coenzyme A
Coenzyme A (CoA-SH) contains pantothenic acid, 3’,5’-ADP and 2-mercaptoethylamine

24. The Hydrolysis of Acetyl-CoA
The metabolically active form of a carboxylic acid is the acyl-CoA thioester with a high-energy thioester bond

25. The Role of Electron Transfer & ATP Production in Metabolism

26. Summary
Metabolic pathways proceed in many stages, allowing for efficient use of energy
Many coenzymes, particularly coenzyme A(HS-CoA) play a crucial role in metabolism