Comprehensive Biochemistry: Biological Macromolecules, Enzyme Kinetics, and the Chemical Properties of Water

Vocabulary practice flashcards covering biological macromolecules, enzymatic mechanisms, and the chemical properties and behavior of water.

Organic Chemistry

The branch of chemistry dedicated to the scientific study of carbon-based compounds.

Hydrocarbons

Highly flammable organic compounds composed exclusively of carbon and hydrogen atoms that combust according to the reaction: $\text{Hydrocarbon} + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O} + \text{heat}$.

Polymer

A large, relatively complex chain macromolecule composed of repeating linked subunits called monomers (from the Greek "poly" meaning many and "meros" meaning part).

Dehydration Synthesis

The chemical reaction that joins individual monomers into polymers by deleting (removing) a molecule of water ($\text{H}_2\text{O}$).

Hydrolysis

The chemical process that breaks polymers down into smaller monomer units by adding a molecule of water ($\text{H}_2\text{O}$).

Carbohydrates

Macromolecules composed of carbon, hydrogen, and oxygen that function primarily in short-term energy supply and structural support.

Monosaccharide

The single sugar monomer unit of carbohydrates, with glucose being a primary example.

Lipids

Hydrophobic macromolecules containing carbon and hydrogen with some oxygen; their functions include long-term energy storage, insulation and protection, cell membrane structure, and chemical messaging.

Phospholipid

A structural membrane lipid consisting of a glycerol molecule joined to a polar, hydrophilic phosphate group head and two nonpolar, hydrophobic fatty acid tails.

Proteins

Macromolecules composed of carbon, hydrogen, oxygen, and nitrogen that provide bodily structure, catalyze cellular reactions (enzymes), transport oxygen (hemoglobin), and mediate cell-to-cell communication.

Amino Acid

The monomer building block of proteins, consisting of a central carbon bonded to an amino group, a carboxyl group, and a variable side chain; $20$ distinct amino acids are utilized by the human body.

Peptide Bond

The covalent bond that links adjacent amino acids together during dehydration synthesis to build a polypeptide chain.

Four Levels of Protein Structure

The structural hierarchy of proteins: primary (amino acid sequence), secondary (hydrogen-bonded folding into coils or sheets), tertiary (three-dimensional polypeptide conformation), and quaternary (assembly of multiple polypeptide subunits).

Nucleic Acids

Macromolecules composed of carbon, hydrogen, nitrogen, oxygen, and phosphorus ($\text{CHNOPS}$) that store and transmit genetic information and carry instructions for building proteins.

Nucleotide

The repeating monomer unit of nucleic acids, consisting of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Catalyst

A substance that speeds up the rate of a chemical reaction without undergoing any permanent change itself during the process.

Enzyme

A biological protein catalyst that accelerates metabolic reactions by reducing activation energy without being altered or consumed in the reaction.

Activation Energy

The minimum energy input required to initiate a chemical reaction; enzymes speed up reactions by substantially reducing this threshold.

Substrate

The specific chemical reactant upon which an enzyme acts during a catalyzed reaction.

Active Site

The specialized groove or pocket on an enzyme where the substrate binds to form an enzyme-substrate complex.

Lock and Key Model

A model of enzymatic specificity stating that the shape of the enzyme's active site and the shape of the substrate fit together precisely like a lock and key.

Induced Fit Model

A model of enzyme action stating that the binding of the substrate induces a slight change in the shape of the active site to produce an exact conformational fit.

Catabolic Reaction

A chemical pathway catalyzed by enzymes that breaks down a complex substrate into smaller, simpler products.

Anabolic Reaction

A synthetic metabolic reaction wherein an enzyme combines multiple smaller substrates into a larger, bonded product.

Denaturation

The process by which an enzyme loses its characteristic three-dimensional shape and function when exposed to temperatures above $40^\circ\text{C}$ or pH values outside its optimal range.

Polarity of Water

The uneven distribution of electron density in a water molecule, producing a slight negative charge ($\delta^-$) on the oxygen atom and slight positive charges ($\delta^+$) on the two hydrogen atoms.

Universal Solvent

A property of water derived from its polarity that enables it to dissolve many polar substances and salts, creating an aqueous medium for cellular metabolism.

Cohesion

The attractive force that binds water molecules to one another through hydrogen bonding.

Adhesion

The intermolecular attraction between water molecules and other distinct polar surfaces or molecules.

Surface Tension

The strong cohesive force at the surface of a liquid body that creates an elastic layer, allowing organisms denser than water (such as insects) to walk across the water's surface.

Capillary Action

The movement of water upward against gravity through narrow plant vessels called xylem, driven jointly by cohesion and adhesion.

Density of Solid Water (Ice)

The unique characteristic whereby water expands upon freezing to form a crystalline lattice, making solid ice less dense than liquid water and allowing it to float.

High Specific Heat

The capacity of water to absorb large amounts of thermal energy before changing temperature, thereby stabilizing environmental and internal body temperatures to support homeostasis.

High Heat of Vaporization

The substantial amount of thermal energy required to convert liquid water into gas (steam), enabling evaporative cooling through sweat.

pH

A measure of the concentration of hydrogen ions ($\text{H}^+$) in an aqueous solution, governed by the dissociation balance $[\text{H}^+] + [\text{OH}^-] \rightleftharpoons \text{H}_2\text{O}$, where neutral water has a value of $7$.

Acid

A solution containing a higher concentration of $\text{H}^+$ ions than pure water, characterized by a pH value strictly below $7$.

Base (Alkaline)

A solution containing fewer $\text{H}^+$ ions and a high concentration of $\text{OH}^-$ ions compared to pure water, characterized by a pH value strictly above $7$.

The pH Scale

A numerical scale ranging from $0$ to $14$ indicating relative acidity or alkalinity, with common examples such as battery acid ($0$), water ($7$), and drain cleaner ($14$).