Macromolecules and Enzyme Structure and Function

Comprehensive vocabulary flashcards reviewing macromolecules, protein folding levels, enzyme kinetics, and factors affecting enzyme activity.

Enzyme

A specialized protein that acts as a biological catalyst to speed up chemical reactions inside cells without being consumed or permanently altered in the process.

Biological Catalyst

A substance that accelerates the rate of a chemical reaction inside living cells by lowering the required activation energy, remaining unchanged after the reaction completes.

Substrate

The specific reactant molecule that binds to an enzyme and is worked on to be either broken down into simpler parts or joined into larger molecules.

Active Site

The specific region or pocket on the surface of an enzyme where the substrate binds to undergo a chemical reaction.

Enzyme-Substrate Complex

The temporary intermediate structure formed when a substrate molecule binds precisely into the active site of its complementary enzyme.

Lock and Key Model

A model of enzyme action proposing that an enzyme's active site possesses a specific geometric shape into which only one complementary substrate fits precisely, analogous to a key fitting into a lock.

Activation Energy

The minimum energy barrier that must be overcome for a chemical reaction to occur, represented by the peak of a reaction coordinate curve which enzymes lower.

Catabolic Reaction

A biochemical reaction that breaks down complex substrates into simpler substances, such as cellular respiration and the digestive breakdown of proteins into amino acids.

Anabolic Reaction

A biochemical reaction that puts simpler molecules together to synthesize more complex substances, such as photosynthesis or combining glucose monomers into lipids for energy storage.

Denaturation

The process by which extreme temperatures, extreme pH, or certain chemicals alter an enzyme's three-dimensional shape, distorting the active site so substrates can no longer bind.

Collision Theory

A principle stating that for a chemical reaction to occur, reactant molecules must collide with adequate energy and in the correct orientation, meaning higher concentrations increase reaction rates.

Optimal Temperature

The ideal temperature at which an enzyme demonstrates maximum catalytic activity, typically around $37^\circ\text{C}$ for human enzymes.

Optimal pH

The specific pH value at which a given enzyme maintains its optimal three-dimensional shape and catalyzes reactions at its highest rate.

Pepsin

A digestive enzyme active in the highly acidic environment of the stomach, operating at an optimal pH of approximately $2$.

Trypsin

A digestive enzyme functioning in the small intestine that operates optimally under slightly basic conditions at a pH of approximately $8$.

Catalase

An intracellular enzyme that speeds up the decomposition of toxic hydrogen peroxide into water and oxygen gas ($2\,H_2O_2 \rightarrow 2\,H_2O + O_2$), functioning best at a neutral pH of $7$.

Enzyme Saturation

The operational condition reached when all active sites on available enzyme molecules are continuously occupied by substrate, resulting in a constant maximum reaction rate regardless of additional substrate.

Amino Acid

The monomer building block of proteins, structured around a central carbon bonded to a hydrogen atom, an amine group, a carboxyl acid group, and a variable R group / side chain.

Primary Protein Structure

The initial level of protein organization consisting of the linear sequence of amino acids joined together in a polypeptide chain.

Secondary Protein Structure

The structural conformation formed when the amino acid chain is linked by hydrogen bonds, forming arrangements such as alpha helices and pleated sheets.

Tertiary Protein Structure

The overall three-dimensional folding of a single polypeptide chain resulting from attractions and interactions between alpha helices and pleated sheets.

Quaternary Protein Structure

The complex structural level consisting of a functional protein composed of more than one folded amino acid chain.

Carbohydrates

Macromolecules consisting of ring-like carbon, hydrogen, and oxygen structures whose monomers are monosaccharides, functioning as short-term energy storage.

Lipids

Hydrophobic macromolecules composed of fatty acid chains and glycerol, essential for long-term energy storage, thermal insulation, shock absorption, and constituting cell membranes.

Nucleic Acids

Polymers composed of nucleotide monomers (including DNA and RNA) whose primary biological function is to store and transfer genetic information.

pH Scale

A measurement scale ranging from $0$ to $14$ that quantifies acidity and alkalinity, where values below $7$ are acidic, $7$ is neutral, and values above $7$ are alkaline.

Reactants

The starting substances that enter into a chemical reaction and undergo chemical transformation, positioned on the left side of a chemical equation.

Products

The new chemical substances formed as an outcome of a completed chemical reaction, positioned on the right side of a chemical equation.

Cellular Respiration

A catabolic pathway described by $C_6H_{12}O_6 + 6\,O_2 \rightarrow 6\,CO_2 + 6\,H_2O + 36\,\text{ATP}$, which breaks down glucose to release cellular energy.

Photosynthesis

An anabolic metabolic pathway where carbon dioxide and water are combined in the presence of light and chlorophyll to produce glucose, oxygen, and water ($6\,CO_2 + 12\,H_2O \rightarrow C_6H_{12}O_6 + 6\,O_2 + 6\,H_2O$).