Major Points
1. Energy --> organization
2. Enzymes catalyze reactions
3. Metabolic energy f ATP
First Law of Thermodynamics
Energy can be neither created nor destroyed, only converted from one form
to another.
Energy is Converted by Cells
* Energy can not be recycled.
* Potential energy in molecules can be converted.
* Metabolism = rearrangement of molecules ("metabolism" = Greek
for "change")
- "Catabolism": break down of molecules
- "Anabolism": building up of molecules
Entropy
Second law of thermodynamics:
"In a closed system, disorder is constantly increasing"
* The only way to overcome entropy is with addition of energy
Enzymes
* Enzymes accelerate the rates of reactions that happen slowly by themselves
* They are not altered
* They catalyze both forward and reverse reactions
* They are specific toward substrates
Coenzymes & Cofactors
Some enzymes require helper molecules:
* Coenzymes: small molecules which participate in reactions
- Nicotinamide adenine dinucleotide (NAD) carries electrons
* Cofactors: small molecules which combine with proteins
- A heme group binds to cytochrome proteins and carries electrons
Structure of ATP
Figure 16.15 (a) in Starr & Taggart
Structure of ATP
Figure 16.15(b) in Starr & Taggart
Electron Transport Chains
Figure 16.14(b) in Starr & Taggart