Chapter 3: The Chemical Level of Organization – Vocabulary (A&P)

Vocabulary flashcards covering key terms and concepts from Chapter 3: The Chemical Level of Organization in Anatomy & Physiology.

Matter

Anything that occupies space and has mass.

Mass

The amount of matter in an object; mass is constant regardless of location.

Weight

The force of gravity on an object's mass; can vary with location.

Element

A pure substance made of a single type of atom.

Atom

The smallest unit of an element that retains its properties.

Molecule

Two or more atoms chemically bound together.

Compound

Two or more elements joined by chemical bonds.

Subatomic Particles

Particles that make up atoms: protons, neutrons, and electrons.

Proton

Positively charged subatomic particle in the nucleus.

Neutron

Electrically neutral subatomic particle in the nucleus.

Electron

Negatively charged subatomic particle surrounding the nucleus.

Periodic Table

Organization of elements; each box shows atomic number, atomic weight, name, and symbol.

Atomic Number

Number of protons in an atom's nucleus.

Atomic Weight

Total number of protons and neutrons (plus a small electron contribution).

Mass Number

Approximate sum of protons and neutrons in the nucleus.

Isotope

Forms of the same element with different numbers of neutrons.

Protium

Hydrogen isotope with 1 proton and 0 neutrons.

Deuterium

Hydrogen isotope with 1 proton and 1 neutron.

Tritium

Hydrogen isotope with 1 proton and 2 neutrons; radioactive.

Ion

Atom with a net electrical charge due to gain or loss of electrons.

Cation

Positively charged ion.

Anion

Negatively charged ion.

Electron Shells

Regions around the nucleus that hold electrons; 2 in the first shell, up to 8 in others.

Valence Shell

Outermost electron shell; determines bonding behavior.

Bond

Electrical attraction that holds atoms together.

Ionic Bond

Bond formed between oppositely charged ions (e.g., Na+ and Cl−).

Covalent Bond

Bond formed when electrons are shared between atoms.

Polar Covalent Bond

Covalent bond with unequal sharing of electrons, creating partial charges.

Nonpolar Covalent Bond

Covalent bond with equal sharing of electrons.

Hydrogen Bond

Weak attraction between molecules, commonly between water molecules.

Water

Polar solvent; universal solvent; involved in dehydration synthesis and hydrolysis; makes up ~50–70% of the body.

Solvent

Substance that dissolves another substance in a solution.

Solute

Substance dissolved in the solvent.

Solution

A mixture where a solute is dissolved in a solvent.

Dehydration Synthesis

Bond formation that releases a water molecule.

Hydrolysis

Chemical breakdown of a compound using water.

pH

Scale (0–14) of acidity/alkalinity; 7 is neutral; lower is acidic, higher is basic.

Buffers

Substances that resist changes in pH to maintain stability.

Inorganic Compounds

Do not contain both carbon and hydrogen (e.g., water, salts, acids, bases, CO2).

Organic Compounds

Contain carbon and hydrogen (e.g., carbohydrates, lipids, proteins, nucleic acids).

Carbohydrates

Organic macromolecules with C, H, O; main energy source; monosaccharides, disaccharides, polysaccharides.

Monosaccharides

Simple sugars (e.g., glucose, fructose, galactose, ribose, deoxyribose).

Disaccharides

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

Polysaccharides

Many monosaccharides; starches, glycogen, cellulose.

Functions of Carbohydrates

Primary energy source (ATP), structural roles, cellular signaling and membranes via glycolipids/glycoproteins.

Lipids

Hydrophobic organic molecules; nonpolar; major energy source; includes triglycerides, phospholipids, steroids, prostaglandins.

Triglycerides

Glycerol plus three fatty acids; most common dietary lipid; energy storage.

Saturated Fat

Fatty acids with max hydrogen; single bonds; typically solid at room temperature.

Unsaturated Fat

Fatty acids with double bonds; kinks; typically liquid at room temperature.

Phospholipids

Lipids with a phosphate-containing head and two fatty acid tails; key in membranes.

Sterols

Ring-structured lipids (e.g., cholesterol); membrane stability and hormone precursors.

Prostaglandins

Lipids derived from unsaturated fatty acids; involved in inflammation.

Proteins

Macromolecules made of amino acids; provide structure, transport, and catalysis; four structural levels.

Amino Acids

Monomers of proteins; 20 common types; each has an amino group, a carboxyl group, and an R group.

Peptide Bonds

Bonds linking amino acids via dehydration synthesis.

Primary Structure

Linear sequence of amino acids in a protein.

Secondary Structure

Stable folds like alpha-helix or beta-pleated sheet formed by hydrogen bonds.

Tertiary Structure

Overall 3D folding of a protein due to interactions among R groups.

Quaternary Structure

Interactions between two or more polypeptide chains.

Denaturation

Unfolding of a protein; loss of function due to heat, pH, or chemicals.

Enzymes

Biological catalysts that speed up reactions by lowering activation energy; usually proteins.

Active Site

Region of the enzyme where the substrate binds.

Enzyme-Substrate Complex

Temporary complex formed when substrate binds to enzyme.

Activation Energy

Minimum energy required for a reaction to occur.

Nucleic Acids

DNA and RNA; store genetic information and participate in protein synthesis.

DNA

Deoxyribonucleic acid; double-stranded; stores genetic code.

RNA

Ribonucleic acid; single-stranded; participates in protein synthesis.

Nucleotides

Monomers of nucleic acids; consist of a sugar, a phosphate group, and a nitrogenous base.

Bases

Purines (adenine and guanine) and pyrimidines (cytosine, thymine, uracil).