1.
Activation Energy: The extra energy needed to destabilize existing chemical bonds and initiate a chemical reaction.
2.
Active Site: Where an enzyme will bind to a substrate.
3.
Active Sites, Enzymes, and Substrates: Substrates bind to the active site of an enzyme. Enzymes adjust their shape to the substrate so there is a better fit.
4.
ADP: Adenosite triphosphate; what forms when ATP is hydrolyzed to release energy and an inorganic phosphate group.
5.
Allosteric Activator: A substance that binds to allosteric sites to keep an enzyme in its active configuration.
6.
Allosteric Enzymes: Enzymes that can exist in either an active or inactive conformation.
7.
Allosteric Inhibitor: A substance that binds to an allosteric site and reduces enzyme activity.
8.
Allosteric Site: Non-active sites on an enzyme that inhibitors can bind to.
9.
AMP: Adenosine Monophosphate; doesn't have high-energy bonds, though.
10.
Anabolism: Reactions that expend energy to build up molecules.
11.
ATP: Adenosine triphosphate (ATP) is the molecular currency used for cellular energy transactions.
12.
ATP cycles continuously: ATP hydrolysis releases energy to drive endergonic reactions, and it is synthesized with energy from exergonic reactions.
13.
ATP hydrolysis drives endergonic reactions.: Enzymes hydrolyze the terminal phosphate group of ATP to release energy for reactions. If ATP hydrolysis is coupled to an endergonic reaction with a positive ∆G with magnitude less than that for ATP hydrolysis, the two reactions together will be exergonic.
14.
Biochemical Pathway: Sequences of reactions to create a specific product or produce a specific effect.
15.
Catabolism: Reactions that harvest energy by breaking down molecules.
16.
Catalyst: Substances that lower activation energy needed to initiate a reaction.
17.
Cells store and release energy in the bonds of ATP.: The energy of ATP is stored in the bonds between its terminal phosphate groups. These groups repel each other due to their negative charge and therefore the covalent bonds joining these phosphates are unstable.
18.
Chemical reactions can be predicted based on changes in free energy.: Free energy (G) is the energy available to do work in any system. Changes in free energy (∆G) predict the direction of reactions. Reactions with a negative ∆G are spontaneous (exergonic) reactions, and reactions with a positive ∆G are not spontaneous (endergonic). Endergonic chemical reactions absorb energy from the surroundings whereas exergonic reactions release energy to the surroundings.
19.
Coenzyme: A cofactor that is a nonprotein organic molecule. Many vitamins are coenzymes, ex. B₆ and B₁₂.
20.
Cofactors: Additional chemical components that aid in enzyme function, ex. metal ions found in the active site.
21.
Competitive Inhibitor: An inhibiting substrate that compete with other substrates for the active site on the enzyme.
22.
Endergonic Reaction: Any reaction requiring an input of energy.
23.
Energy can take many forms.: Energy is the capacity to do work. Potential energy is stored energy, and kinetic energy is the energy of motion. Energy can take many forms: mechanical, heat, sound, electric current, light, or radioactive radiation. Energy is measured in units of heat known as kilocalories.
24.
Enthalpy: The energy contained within a molecule's chemical bonds.
25.
Entropy: The formal term for disorder.
26.
Enzyme consumption: Enzymes are not consumed; they are reused, unless rendered inactive.
27.
Enzyme-Substrate Complex: The whole thing consisting of both the enzyme and the substrate.
28.
Enzymes occur in many forms: Enzymes can be free in the cytosol or exist as components bound to membranes and organelles. Enzymes involved in a biochemical pathway can form multienzyme complexes. While most enzymes are proteins, some are actually RNA molecules, called ribozymes.
29.
Exergonic Reaction: Any reaction that releases free energy as heat.
30.
Feedback Inhibition: A process in which the end product of a biochemical pathway acts as an inhibitor of an early reaction in the pathway.
31.
Free Energy: The energy available to do work in a system.
32.
G
∆G: G = H - TS
∆G = ∆H - T∆S
33.
Harnessing Heat to do Work: Heat can only be harnessed to do work when there is a heat gradient, or temperature difference between two areas.
34.
Heat: A measure of the random motion of molecules; a measure of a form of kinetic energy.
35.
Induced Fit: The fit between the enzyme and the substrate.
36.
Inhibitors: A substance that binds to an enzyme and decreases its activity. There are two kinds of inhibitors: competitive, and noncompetitive.
37.
Inorganic Phosphate: P₋i
A phosphate group that came off of a larger molecule.
38.
Intermolecular Catalysis: A process; some ribozymes act on other molecules without being changed themselves.
39.
Intramolecular Catalysis: A process; some ribozymes have folded structures and catalyze reactions on themselves.
40.
Kinetic Energy: The energy of motion.
41.
Metabolism: The total of all chemical reactions carried out by an organism.
42.
Multienzyme Complex: Noncovalently bonded assemblies containing multiple enzymes.
43.
Multienzyme complex advantages: - transfers substrates to next enzyme more quickly than if free-floating
- unwanted side reactions prevented
- all reactions taking place within the complex can be controlled as a unit
44.
Noncompetitive Inhibitor: An inhibiting substrate that binds to an allosteric site on an enzyme, changing its shape so that it becomes inhibited.
45.
Optimal Factors: Enzymes work best at certain temperatures, pHs, etc.
46.
Oxidation-reduction reactions transfer electrons while bonds are made or broken.: Oxidation is a reaction involving the loss of electrons. Reduction is the gain of electrons. These two reactions take place together and are therefore termed redox reactions.
47.
Potential Energy: Stored energy.
48.
Ribozymes: Enzymes that are not made of protein, but RNA. There are two types of ribozymes: those that experience intramolecular catalysis, and those that experience intermolecular catalysis.
49.
Spontaneous chemical reactions require activation energy.: Activation energy is the energy required to destabilize chemical bonds and initiate chemical reactions. Even exergonic reactions require this activation energy . Catalysts speed up chemical reactions by lowering the activation energy.
50.
Substrate: The molecule that will undergo the reaction.
51.
The ATP Cycle: ATP is recycled; it releases energy for the cell to use via hydrolysis; the released ADP and P₋i is put back together with energy from exergonic cellular reactions.
52.
The First Law of Thermodynamics: Energy cannot be created nor destroyed.
53.
The First Law states that energy cannot be created or destroyed.: Virtually all activities of living organisms require energy. Energy changes form as it moves through organisms and their biochemical systems, but it is not created or destroyed.
54.
The Second Law of Thermodynamics: The entropy of the universe is continuously increasing.
55.
The Second Law states that some energy is lost as disorder increases.: The disorder, or entropy, of the universe is continuously increasing. In an open system like the Earth, which is receiving energy from the Sun, this may not be the case. To increase order however, energy must be expended. In energy conversions, some energy is always lost as heat.
56.
The structure of ATP: ATP consists of three components: a five-carbon sugar, ribose, as the backbone; adenine, a nitrogenous base; and a chain of three phosphates.
57.
The Sun provides energy for living systems.: Photosynthesis stores light energy from the Sun as potential energy in the covalent bonds of sugar molecules. Breaking these bonds in living cells releases energy for use in other reactions.
