Biochemistry & Introductory Physics – Vocabulary Review

Vocabulary flashcards covering biochemical functional groups, enzyme binding models, spectrophotometry, basic physics concepts, and phase changes.

Lactone

A cyclic ester formed by intramolecular esterification of a molecule containing both a hydroxyl and a carboxylic acid group.

Lactam

A cyclic amide produced when an amino group and a carboxylic acid group within the same molecule form a ring.

Intramolecular Esterification

Reaction in which an alcohol and carboxylic acid on the same molecule combine, eliminating water and creating a cyclic ester (lactone).

Saponification

Base-catalyzed hydrolysis of an ester that yields a carboxylate salt (soap) and an alcohol.

Carbamate

Functional group containing both an ester and an amide bond; common in pesticides and pharmaceuticals.

Lock-and-Key Model

Early enzyme model proposing that the active site has a rigid shape complementary to the substrate.

Induced Fit Model

Enzyme model in which the active site changes shape upon substrate binding to achieve optimal interaction.

Conformational Selection Model

Concept that an enzyme exists in multiple conformations and the substrate binds the one that is already compatible.

Cooperative Binding

Substrate binding that increases the enzyme’s or protein’s affinity for additional substrate molecules, as in hemoglobin.

Ordered Mechanism

Multi-substrate enzyme mechanism where substrates must bind in a specific sequence (A before B).

Random Mechanism

Multi-substrate enzyme mechanism where substrates can bind in any order before catalysis.

Ping-Pong Mechanism

Double-displacement enzyme mechanism in which one substrate binds, product leaves, and a second substrate then binds; no ternary complex forms.

Beer–Lambert Law

Relationship A = ε c l linking absorbance (A) to concentration (c), molar absorptivity (ε), and path length (l).

Molar Absorptivity (ε)

Proportionality constant in Beer–Lambert Law that describes how strongly a substance absorbs light at a given wavelength.

Path Length

Distance light travels through a sample (typically 1 cm in cuvettes) used in Beer–Lambert calculations.

Phosphatase

Enzyme that hydrolyzes phosphate esters using a nucleophilic side chain to form a transient covalent intermediate.

Reflection

Process in which light or sound waves bounce off a surface and return to the original medium.

Refraction

Bending of a wave as it passes from one medium to another with different density, e.g., a straw appearing bent in water.

Diffraction

Spreading and interference pattern of waves when they encounter an obstacle or slit, producing bright and dark regions.

Amphipathic Molecule

Compound containing both polar (hydrophilic) and non-polar (hydrophobic) regions; fatty acids are an example.

Gravitational Potential Energy

Energy stored due to an object’s height in a gravitational field; calculated by E = m g h.

Newton’s First Law

Law of inertia: an object at rest stays at rest and an object in motion stays in motion unless acted on by a net force.

Newton’s Second Law

Fundamental relation F = m a stating that net force on an object equals mass times acceleration.

Average Force (Impulse)

Force calculated from the change in momentum over time: F = Δp / Δt.

Specific Heat Capacity

Amount of energy required to raise the temperature of 1 kg of a substance by 1 °C; for water, 4.185 kJ kg⁻¹ °C⁻¹.

Fusion (Melting)

Phase change in which a solid becomes a liquid as energy is absorbed.

Vaporization (Boiling)

Phase transition from liquid to gas that requires significant energy input (latent heat).

Sublimation

Direct transition from solid to gas without passing through the liquid phase.

Deposition

Phase change in which a gas transforms directly into a solid without becoming a liquid first.

Water’s High Specific Heat

Property that water resists temperature change, requiring large amounts of energy for heating or cooling.

Fatty Acid Solubility

Characteristic whereby shorter hydrocarbon chains increase solubility in water due to a higher polar-to-non-polar ratio.