Chapter 2 (PART ONE)

Vocabulary flashcards covering key terms from Chapter 02: Chemical Basis of Life.

Chemistry

The branch of science dealing with the composition and properties of chemicals; essential for understanding physiology because body processes involve chemicals.

Matter

Anything that has weight (mass) and takes up space.

Element

The smallest units of matter with specific chemical properties.

Atom

The smallest unit of an element.

Molecule

Two or more atoms bonded together.

Ion

An atom that has gained or lost electrons and is charged.

Chemical Bond

Attractions between two or more atoms.

Ionic Bond

A bond formed by attraction between oppositely charged ions; forms crystal arrays rather than molecules.

Covalent Bond

A bond formed when atoms share electrons; can be single, double, or triple.

Polar Covalent Bond

A covalent bond in which electrons are not shared equally, creating partial positive and negative ends in a molecule.

Hydrogen Bond

A weak attraction between a slightly positive hydrogen atom and a slightly negative atom (N or O) in another molecule.

Isotope

Atoms of the same element with the same atomic number but different mass numbers; some isotopes are stable, others radioactive.

Atomic Number

The number of protons in an atom's nucleus.

Atomic Mass

The total number of protons and neutrons in the nucleus.

Proton

Positively charged subatomic particle in the nucleus.

Neutron

Neutral subatomic particle in the nucleus.

Electron

Negatively charged subatomic particle surrounding the nucleus; very small.

Acid

An electrolyte that releases hydrogen ions in water.

Base

An electrolyte that releases ions that combine with hydrogen ions in water.

pH

A measure of hydrogen ion concentration in solution; scale 0-14; 7 is neutral; lower values are acidic, higher values are basic; buffers minimize pH changes.

Buffer

Chemicals that bind excess acids or bases to minimize pH changes in body fluids.

Electrolyte

Substances that dissociate in water to carry electric charge in the body.

Organic Compound

Compounds that contain hydrogen and carbon; many are nonelectrolytes.

Inorganic Substances

Substances that do not contain both carbon and hydrogen; usually dissolve in water and release ions.

Water

The most abundant inorganic compound; solvent; major component of body fluids; transports solutes and absorbs heat.

Carbohydrate

Organic substance providing energy and materials for cell structures; composed of C, H, and O with more H than O.

Monosaccharide

Simple sugars; 5–6 carbon atoms; examples include glucose, fructose, galactose, ribose, and deoxyribose.

Disaccharide

Double sugars; examples include lactose, sucrose, and maltose.

Polysaccharide

Many monosaccharides joined together; examples include glycogen and starch.

Lipid

Organic substances insoluble in water; include triglycerides, phospholipids, and steroids.

Triglyceride

A lipid with glycerol bound to three fatty acids; major energy source stored in fat tissues.

Phospholipid

Two fatty acids and a phosphate group bound to glycerol; phosphate head is hydrophilic, tails are hydrophobic; essential in membranes.

Steroid

Lipids with four fused carbon rings; include cholesterol and hormone precursors.

Protein

Organic compounds containing C, H, O, N (and often S); perform structural, enzymatic, regulatory, and other functions; built from amino acids.

Amino Acid

Building blocks of proteins; each has an amino group, a carboxyl group, and a variable R group; there are about 20 kinds.

Peptide Bond

Bond that links amino acids together in a polypeptide chain.

Nucleic Acids

Large organic molecules that form genes and govern protein synthesis; built from nucleotides.

Nucleotide

The basic unit of nucleic acids; consists of a five‑carbon sugar, a phosphate group, and a nitrogenous base.

DNA

Deoxyribonucleic acid; double‑stranded; stores genetic code; sugar is deoxyribose.

ATP

Adenosine triphosphate; energy‑storing molecule with three phosphate groups; derived from RNA function.

Enzyme

Biological catalyst that speeds up chemical reactions without being consumed.

Levels of Protein Structure

Primary (amino acid sequence), Secondary (pleated/α-helix from hydrogen bonds), Tertiary (3D folding), Quaternary (assembly of multiple polypeptides).

Denaturation

Irreversible disruption of a protein's shape and function caused by pH, temperature, radiation, or chemicals.