1. Catabolic reaction is a reaction that results in the breakdown of complex substances.
Anabolic reaction is when complex substances from simpler forms are constructed.
Metabolism = All anabolic and catabolic processes in a cell/organism.
2. First Law of Thermodynamics: The total amount of energy in the universe is constant. Energy cannot be created or destroyed but only converted from one form into another.
3. Second Law of Thermodynamics: The entropy of the universe increases with any change that occurs.
4. All forms of energy can be categorized as kinetic energy, the energy possessed by a moving object, or potential energy which refers to the stored energy. Some forms of kinetic energy include thermal energy, mechanical energy, electrical energy and electromagnetic energy. Some examples of potential energy are gravitational potential energy and chemical potential energy.
5. Bond energy is a measure of the stability of a covalent bond and is measured in kilojoules (kJ). Bond energy equals to the minimum energy required to break one mole of bonds between two types of atoms. It also indicates the amount of energy released when a bond is formed.
6. Activation energy is the difference between the potential energy level of transition state and the potential energy of reacting molecules.
Transition state is a temporary condition during a chemical reaction in which the bonds within reactants are breaking and the bonds between products are forming.
7. If the bonds in products are more stable than those in the reactants, more energy is released during bond formation than was absorbed during bond breaking. As a result, this will result in a net energy output and this reaction is known as an exothermic reaction.
9. Entropy refers to a measure of the randomness or disorder in energy or in a system.
In chemical reactions, entropy increases when:
- solid reactants become liquid or gaseous products
- liquid reactants become gaseous products
- fewer moles of reactant molecules form a greater number of moles of product molecules
- complex molecules react to form simpler molecules (polymers into monomers, or glucose into carbon dioxide and water)
- solutes move from an area of high concentration to an area of lower concentration until they are uniformly distributed in the given volume (diffusion)
10. Exergonic reaction is spontaneous and is accompanied by a decrease in Gibbs free energy. (
11. Endergonic reaction is not spontaneous and is accompanied by an increase in Gibbs free energy. ( Change in Gibbs free energy is positive)
12. Adenosine triphosphate (ATP) is the primary source of free energy in living cells.
13. Phosphorylation is the process of attaching a phosphate group to an organic molecule.
14. Oxidation is when an atom loses one or more electrons during a chemical reaction. Reduction is when an atom gains one or more electrons.
15. An electron transfer between two substances always involves an oxidation and a reduction and this is known an redox reaction.
16. Substrate is the reactant that an enzyme acts on when it catalyzes a chemical reaction. The active site is the location where the substance binds to an enzyme (protein catalyst).
17. Many substances inhibit enzyme activity. Competitive inhibitors enter the enzyme’s active site and block the normal substrate from binding.
18. Non competitive inhibitors attach to another site on the enzyme (not the active site), causing a change in the enzyme’s shape. As a result, the changes in active site in such a way that it loses affinity for its substrate.
19. Feedback inhibition is a method used by cells to control metabolic pathways in which a product formed later in the sequence of reactions allosterically inhibits an enzyme that catalyzes a reaction occurring earlier in the process.
20. Cells control metabolic processes by restricting the location of enzymes and enzyme complexes to certain locations within the cell.
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