Enzymes and Metabolism Practice Flashcards

This set of vocabulary flashcards covers the fundamental concepts of enzymes, metabolic pathways, bioenergetics, and enzyme inhibition as described in the lecture notes.

Metabolism

The complex network of interdependent and interacting chemical reactions occurring in living organisms.

Reactants

The substances that participate in a chemical reaction.

Products

The substances that are formed as a result of a chemical reaction.

Enzymes

Highly specific globular proteins that act as organic catalysts to control the rate of chemical reactions in organisms.

Catalysts

Substances that increase the rate of chemical reactions without being consumed in the process.

Anabolism

The metabolic process of building complex organic macromolecules from simpler monomers, typically requiring energy and releasing water.

Catabolism

The metabolic process of breaking down complex organic molecules into simpler monomers, releasing energy as they occur.

Condensation Reactions

Chemical reactions used in anabolism to form macromolecules from monomers, such as in protein synthesis or glycogen formation.

Hydrolysis

The splitting of molecules by adding water, used in catabolic reactions like digestion to break macromolecules into monomers.

Kinetic Energy

The energy of motion, which includes the movement of molecules within objects.

Potential Energy

Stored energy or energy in a form that is not being utilized at a specific point in time.

Chemical Energy

A form of potential energy available for release when a chemical reaction occurs.

Thermal Energy

A form of kinetic energy stored within objects that is capable of being transferred as heat.

Kilocalorie (kcal)

A unit of heat measurement used in biology equivalent to $1000\,calories$, or the heat necessary to raise the temperature of $1\,g$ of water by $1\,^{\circ}C$.

Joule

A unit of energy where one joule equals $0.239\,cal$.

Adenosine Triphosphate (ATP)

The energy currency of the cell, composed of adenine, ribose, and three phosphate groups, providing energy for cellular activities.

Ribozyme

A ribonucleic acid (RNA) molecule that acts as an organic catalyst.

Active Site

A specific area in the three-dimensional shape of an enzyme, composed of a few amino acids, where the substrate binds for catalysis.

Denaturation

A process where an enzyme loses its specific three-dimensional shape and functional capability due to factors like extreme pH or temperature.

Induced-fit Model

A model of enzyme action where both the substrate and the enzyme undergo conformational changes upon binding to provide a better fit and destabilize chemical bonds.

Activation Energy

The minimum amount of kinetic energy required to destabilize existing bonds in a substrate so that a reaction can proceed.

Exergonic Reactions

Bioenergetic reactions that release energy, resulting in products with less energy than the reactants.

Endergonic Reactions

Bioenergetic reactions that absorb energy, resulting in products with a higher energy level than the reactants.

Collision Theory

The principle stating that reactants must collide with sufficient energy and in the correct orientation for a chemical reaction to occur.

Immobilized Enzymes

Enzymes attached to stationary surfaces or embedded in membranes to allow for more efficient chemical reactions or industrial use.

Enzyme-Substrate Complex

A temporary structure formed when a substrate molecule binds to the active site of an enzyme.

Optimum Temperature

The specific temperature at which a particular enzyme works most efficiently.

Intracellular Enzymes

Enzymes that function within the cell, such as those used in Glycolysis (cytoplasm) and the Krebs cycle (mitochondria).

Extracellular Enzymes

Enzymes that function outside the cell, such as those involved in chemical digestion within the gut.

Endotherms

Animals, such as birds and mammals, that utilize heat generated from metabolic reactions to maintain a constant internal body temperature.

Metabolic Pathways

Sequences of enzyme-catalysed reactions where the product of one reaction becomes the substrate for the next.

Linear Pathway

A metabolic pathway that starts with an initial substrate and ends with a different final product, such as Glycolysis.

Cyclical Pathway

A metabolic pathway that begins and ends with the same substance, such as the Krebs cycle or the Calvin cycle.

Cofactors

Inorganic ions or non-protein organic molecules (like vitamins) required at the active site for certain enzymes to function properly.

Non-competitive Inhibition

Also called allosteric inhibition; occurs when an inhibitor binds to an allosteric site, changing the active site's shape and preventing substrate binding.

Competitive Inhibition

Occurs when an inhibitor with a similar structure to the substrate competes directly for the enzyme's active site.

Statins

A group of drugs that act as competitive inhibitors of the enzyme responsible for cholesterol biosynthesis in the liver.

Feedback Inhibition

Also known as end-product inhibition; a regulatory mechanism where the final product of a pathway inhibits the first enzyme in that same pathway.

Essential Amino Acid

An amino acid that cannot be synthesized by the body and must be obtained through the diet; humans require nine, including isoleucine.

Mechanism-based Inhibition

A type of inhibition where an inhibitor binds irreversibly to the active site, causing permanent inactivation, such as penicillin's effect on bacteria.

Transpeptidase

An enzyme that catalyses the last step in bacterial cell wall formation and is the target of the antibiotic penicillin.

Penicillinase

An enzyme produced by resistant bacterial strains that attacks and breaks the molecular structure of penicillin.