Biochemistry: The Chemistry of Life

Vocabulary flashcards covering key biochemical concepts: organic vs inorganic molecules, water properties, pH and buffers, carbohydrates, lipids, nucleic acids, and proteins.

Catalyst

A substance that speeds up a chemical reaction without being consumed; in biology, enzymes are the primary catalysts.

Enzyme

A biological catalyst (usually a protein) that accelerates specific biochemical reactions in living organisms.

Organic compound

A compound that contains carbon; includes carbohydrates, lipids, proteins, and nucleic acids; CO and CO2 are exceptions in this context.

Inorganic compound

A compound that does not contain carbon (excluding the common carbonate exceptions); examples include water and salts.

Carbon

Element with four available bonds (tetravalent); enables formation of diverse, three‑dimensional organic molecules essential for life.

Hydrogen bonding

A weak attraction between polar molecules (e.g., water) that gives water many of its unique properties.

Water (H2O)

Polar solvent with high heat capacity and high heat of vaporization; facilitates biochemical reactions, dissolution, and cushioning.

Polar solvent

A solvent with partially charged regions that can dissolve ionic and other polar substances.

Dissociation

Process by which a compound separates into ions in solution, such as salts in water or water into H+ and OH−.

Salt

An ionic compound formed by electron transfer; dissociates in water to produce ions and electrolytes.

Acid

A substance that donates hydrogen ions (H+) in water; many acids begin with H in their formula; can be strong or weak.

Base

A substance that accepts hydrogen ions (H+) or releases hydroxide ions (OH−); can be strong or weak.

pH

Scale measuring acidity/basicity; negative logarithm of hydrogen ion concentration; 0–14 with 7 neutral; 7.4 is typical blood pH.

Neutralization reaction

Reaction of a strong acid with a strong base to form a salt and water.

Buffer

A system that resists changes in pH by pairing a weak acid with its conjugate base (e.g., carbonic acid/bicarbonate in blood).

Carbonic acid

Weak acid that participates in the bicarbonate buffer system in blood.

Bicarbonate

Conjugate base of carbonic acid; helps buffer changes in pH in the bloodstream.

Strong acid

An acid that completely dissociates in water (e.g., HCl).

Weak acid

An acid that only partially dissociates in water (e.g., carbonic acid).

Strong base

A base that completely dissociates in water (e.g., NaOH).

Weak base

A base that only partly dissociates in water.

Dehydration synthesis

A condensation reaction where monomers join and a water molecule is removed.

Hydrolysis

A reaction that breaks polymers into monomers by adding a water molecule.

Monomer

A small molecule that can join with others to form a polymer.

Polymer

A large molecule built from many monomers (e.g., proteins from amino acids, nucleic acids from nucleotides).

Carbohydrate

Organic compound built from carbon, hydrogen, and oxygen; hydrated carbon; general formula CH2O; primary energy source.

Monosaccharide

Simple sugar; basic unit of carbohydrates (e.g., glucose, fructose, galactose).

Glucose

Six-carbon monosaccharide (C6H12O6); major energy source in the body.

Fructose

Six-carbon monosaccharide isomer of glucose found in fruit and honey.

Galactose

Six-carbon monosaccharide isomer related to glucose; part of some disaccharides.

Disaccharide

Two monosaccharides linked together (e.g., sucrose, maltose, lactose).

Sucrose

Disaccharide: glucose + fructose; common table sugar.

Maltose

Disaccharide: glucose + glucose; product of starch digestion.

Lactose

Disaccharide: glucose + galactose; milk sugar; lactose intolerance due to lactase deficiency.

Glycogen

Storage polysaccharide of glucose in liver and skeletal muscles; quick energy reserve.

Starch

Plant storage polysaccharide comprised of glucose; energy reserve in plants.

Lipid

Group of hydrophobic, nonpolar biomolecules including fats, oils, phospholipids, and steroids.

Triglyceride

Glycerol backbone with three fatty acids; main form of dietary fat; fats are saturated, oils are unsaturated.

Saturated fat

Fatty acids with no double bonds; straight chains; solid at room temperature.

Unsaturated fat

Fatty acids with one or more double bonds; kinked chains; liquid at room temperature; generally healthier.

Trans fat

Hydrogenated unsaturated fats with trans double bonds; associated with negative health effects.

Phospholipid

Lipids with two fatty acids and a phosphate head; amphipathic; principal component of cell membranes.

Amphipathic

Molecule with both hydrophilic (water-loving) and hydrophobic (water-fearing) regions.

Detergent

Molecule with a hydrophilic head and hydrophobic tail that emulsifies oils; analogous to phospholipids in action.

Cholesterol

Sterol lipid; nonpolar; stabilizes membranes; precursor to steroid hormones; involved in vitamin D synthesis.

Steroid

Lipid with four fused carbon rings; includes hormones like testosterone, estrogen, and aldosterone.

Bile salts

Cholesterol-derived compounds that emulsify fats in the small intestine; stored in the gallbladder.

Nucleic acid

DNA and RNA; polymers of nucleotides; store and transmit genetic information.

Deoxyribose

Five-carbon sugar in DNA (deoxyribonucleic acid).

DNA

Deoxyribonucleic acid; carries genetic information; double-helix polymer of nucleotides.

RNA

Ribonucleic acid; involved in protein synthesis and gene regulation; polymer of nucleotides.

Amino acid

Monomer of proteins; 20 standard amino acids; linked by peptide bonds to form proteins.

Protein

Polymer of amino acids; performs structural, enzymatic, transport, and signaling roles in cells.