• Contains derivatives of the B vitamin niacin
• functions as electron carrier
• primarily involved in catabolic (energy yielding) reactions

• Contains derivatives of the B vitamin niacin
• functions as electron carrier
• primarily involved in anabolic (energy-requiring) reactions

1. The surface of the substrate contacts a specific region of the surface of the enzyme molecule, called the active site.
2. A temporary intermediate compound forms, called an enzyme-substrate complex.
3. The substrate molecule is transformed by the rearrangement of existing atoms, the breakdown of the substrate molecule, or in combination with another substrate molecule.
4. The transformed substrate molecules- the products of the reaction- are released from the enzyme molecule because they no longer fit in the active site of the enzyme.
5. The unchanged enzyme is now free to react with other substrate molecules.

1. Termperature- rate increases as temp increases, however elevation beyond a certain temp (optimal temp) drastically reduces the rate.
2. pH- Above or below optimal pH rate for an enzyme will reduce the rate. Extreme changes in pH can cause denaturation.
3. Substrate Concentration- with increasing concentration of substrate molecules, the rate of reaction increases until the active sites on all enzyme molecules are filled, at which point the max rate of reaction is reached.

Competitive Inhibitors fill the active site of an enzyme and compete with the normal substrate for the active site. Unlike the substrate, it does not undergo any reaction to form products- some are reversible, some are not.

Noncompetitive Inhibitors do not compete with the substrate for the enzyme's active site; instead, they interact with another part of the enzyme.

Oxidation: Removal of electrons

Reduction: Gain of electrons

Redox Reaction: An oxidation reaction paired with a reduction reaction.

In biological systems, the electrons are often assiociated with hydrogen atoms.  Biological oxidations are often dehydrogenations.

ATP is generated by the phosphorylation of ADP. Energy from the transfer of a high-energy PO4- to ADP generates ATP directly from a substrate:

C-C-C~P + ADP-->C-C-C + ATP

Energy released from transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP in the electron transport chain and chemiosimosis.

1. Glycolisis-The oxidation of glucose to pyruvic acid

2. The Krebs Cycle- oxidation of acetyl CoA (a derivative of pyruvic acid) to carbon dioxide, with the production of some ATP, energy-containing NADH, and another reduced electron carrier, FADH2 (the reduced form of flavin adenine dinucleotide).

3. In the electron transport chain (system), the energy of the electrosn is used to produce a great deal of ATP.