Biology 131 – Key Terms (Chemistry & Biochemistry Overview)

Vocabulary-style flashcards covering basic chemistry and biochemistry concepts from the notes, including matter, atoms, bonds, water, organic molecules, and biomolecules.

Matter

Anything that occupies space and has mass.

Mass

A measure of the amount of matter in an object; units are grams (g).

Element

The simplest type of matter with unique chemical properties; composed of atoms of only one kind.

Atom

The smallest unit of an element that retains its chemical properties.

Nucleus

The center of an atom containing protons and neutrons.

Proton

Positively charged subatomic particle with mass ~1 amu.

Neutron

Electrically neutral subatomic particle with mass ~1 amu.

Electron

Negatively charged subatomic particle with negligible mass.

Atomic number

Number of protons in the nucleus; identifies the element.

Isotopes

Different atomic forms of an element with varying numbers of neutrons.

Mass number

Total number of protons and neutrons in the nucleus.

Molecule

Two or more atoms held together by chemical bonds.

Avogadro’s number

6.022 × 10^23; number of particles in one mole.

Mole

Amount of substance containing 6.022 × 10^23 particles.

Molar mass

Mass of one mole of a substance in grams; numerically equal to its formula weight.

Hydrogen bond

Intermolecular attraction between a partially positive H and a highly electronegative atom (O, N).

Ionic bond

Bond formed by transfer of electrons, creating oppositely charged ions that attract.

Covalent bond

Bond formed by sharing electrons between atoms.

Nonpolar covalent bond

Covalent bond with equal sharing of electrons.

Polar covalent bond

Covalent bond with unequal sharing due to electronegativity differences.

Electronegativity

Tendency of an atom to attract electrons in a covalent bond.

Cation

Positively charged ion.

Anion

Negatively charged ion.

Electrolyte

Substance that dissociates in water to form ions and conducts electricity.

Nonelectrolyte

Substance that does not dissociate in water and does not conduct electricity.

Solvent

Substance that dissolves the solute.

Solute

Substance dissolved in the solvent.

Solution

Uniform mixture of solute and solvent.

Suspension

Heterogeneous mixture where components separate over time.

Colloid

Mixture with dispersed particles that do not settle.

Osmolality

Number of particles dissolved per kilogram of solution.

Osmolarity

Number of particles dissolved per liter of solution.

pH

Minus log of H+ concentration; scale from 0 (acidic) to 14 (basic).

Acid

Substance that releases H+ in water, increasing [H+].

Base

Substance that accepts H+ (increases [OH−]).

Buffer

Substance that resists pH change by binding/releases of H+. DIY example: bicarbonate system.

Carbohydrate

Biomolecule family of C, H, O; includes monosaccharides, disaccharides, polysaccharides; primary energy source.

Monosaccharide

Simple sugar (e.g., glucose, fructose, galactose).

Disaccharide

Two monosaccharides linked by dehydration synthesis (e.g., sucrose, lactose, maltose).

Polysaccharide

Long chains of monosaccharides (e.g., glycogen, starch, cellulose).

Lipid

Water-insoluble biomolecules including fats, phospholipids, steroids.

Triglyceride

Glycerol bound to three fatty acids; main form of stored fat.

Phospholipid

Lipid with hydrophilic head and hydrophobic tails; key membrane component.

Steroid

Lipid with four fused carbon rings; cholesterol family.

Eicosanoid

Regulatory lipids derived from fatty acids (prostaglandins, thromboxanes, leukotrienes).

Fat-soluble vitamin

Vitamins A, D, E, K; nonpolar, dissolve in fats.

Amino acid

Building block of proteins; contains amino, carboxyl groups, and a side chain (R).

Peptide bond

Covalent bond linking amino acids in proteins.

Protein structure (primary)

Linear sequence of amino acids.

Protein structure (secondary)

Local folding patterns (alpha helix, beta pleated sheet) due to H-bonds.

Protein structure (tertiary)

3D shape of a single polypeptide; interactions among side chains.

Protein structure (quaternary)

Association of multiple polypeptide subunits.

Nucleic acid

Polymer of nucleotides; includes DNA and RNA; store/intermediate genetic information.

Nucleotide

Monomer of nucleic acids; sugar, phosphate, and base.

DNA

Deoxyribonucleic acid; genetic material; double helix; A–T, C–G base pairs.

RNA

Ribonucleic acid; single strand; uses uracil (U) instead of thymine (T).

ATP

Adenosine triphosphate; energy currency of the cell.

ADP

Adenosine diphosphate; product of ATP dephosphorylation.

Hydrolysis

Reaction in which water splits bonds, releasing energy or components.

Dehydration synthesis

Bond formation with removal of water; forms larger biomolecules.

Activation energy

Minimum energy required to start a chemical reaction; enzymes lower it.

Enzyme

Biological catalyst; lowers activation energy; active site; often a protein.

Cofactor

Nonprotein component that assists enzyme activity (cofactors/coenzymes).

Isomer

Molecules with same formula but different structures.

Geometric isomer

Isomers around double bonds (cis/trans) with restricted rotation.

Enantiomer

Mirror-image isomer with four different substituents on a carbon.

Functional group

Specific group of atoms that imparts characteristic reactivity (e.g., -OH, -C=O, -COOH, -NH2, -PO4^3−).

Glucose

C6H12O6; a common monosaccharide.

Glycogen

Animal storage polysaccharide.

Starch

Plant storage polysaccharide.

Cellulose

Plant structural polysaccharide; dietary fiber.

Cholesterol

Steroid involved in membrane structure and hormone regulation.

DNA structure

Double helix held by hydrogen bonds; A pairs with T, C with G.

RNA structure

Usually single-stranded; uses uracil instead of thymine.

Water as solvent

Major body solvent; high heat capacity; stabilizes temperature; participates in reactions.

Hydrogen bond (water context)

H-bond between water molecules influences water’s properties and structure.

Synthesis (anabolism)

Building up of molecules; energy stored in bonds.

Decomposition (catabolism)

Breaking down of molecules; energy released.

Electrolyte dissociation

Ionic compounds dissociate into ions in water and conduct electricity.

Equilibrium

Forward and reverse reaction rates are equal.

Organic chemistry

Chemistry of carbon-containing compounds.

Inorganic chemistry

Chemistry of substances not primarily containing carbon (with exceptions).