20-point note

Laws of Thermodynamics

The First Law of Dynamics :

In the universe, the total amount of energy is constant. Energy cannot be created nor destroyed, it is converted from one form to another. If a substance gains a certain amount of energy, there would be a loss of energy in somewhere else in the universe.

The Second Law of Dynamics:

In a closed system, the entropy of the system increases directly or indirectly when there are any changes or remain constant.

The universe favours an increase in entropy.

Reactions

Exothermic reaction/ exergonic reaction

A chemical reaction in which the energy of the reactants is higher than the energy of the products, more energy is released during bond formation than that was absorbed during bond breaking, the products formed is more stable than the reactants, and heat is released.

Endothermic reaction/ endergonic reaction

A chemical reaction in which the energy of the reactants is lower than the energy of the products, less energy is released during bond formation than that was absorbed during bond breaking, heat is required to initiate the reaction as the products formed is less stable than the reactants.

Metabolism

Metabolism equals to the sum of all catabolic and anabolic processes.

Catabolic processes refer to the breaking down of complex structures into simpler ones.

Anabolic processes refer to the formation of complex molecules and structures from simpler ones.

Redox reactions

Redox reactions (oxidation-reduction) refer to chemical reactions in which reduction and oxidation reactions take place at the same time.

A substance undergoes reduction means that it is gaining electrons while a substance undergoing oxidation means that it is losing electrons.

A reducing reagent is one who oxidises itself but reduces others.

An oxidizing reagent is one who reduces itself but oxidises others.

Enzymes

Substrate is the reactant that an enzyme acts on when it catalyses a chemical reaction.

Substrate binds to the specific active sites on the enzyme, the molecule is now called an enzyme-substrate complex.

Enzyme is a dynamic protein molecule that alters its shape to accommodate the substrate, this model of enzyme activity is called induced-fit model.

Coenzymes are organic nonprotein substances that are required for enzymes to work.

Cofactors are nonprotein substances that are required for enzymes to work.

Inhibitors

Competitive inhibitors compete with substrate to bind into the active sites of the enzymes.

Noncompetitive inhibitors bind into other sites of the enzymes, causing an altering of the shape of the enzyme and hence the active sites of the enzyme lose the affinity for its substrate.

Feedback inhibition refers to the metabolic control in cells which the product formed later in the sequence of reaction steps allosterically inhibits an enzyme that catalyses a reaction occurring earlier in the process.