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Elements

Substances that cannot be broken down into simpler substances by chemical means.

Trace Elements

Elements required by an organism in very small quantities.

Atoms

The unit of life, composed of protons, neutrons, and electrons.

Protons

Positively charged particles in an atom.

Neutrons

Uncharged particles found in the nucleus of an atom.

Electrons

Negatively charged particles orbiting the nucleus of an atom.

Isotopes

Atoms that have the same number of protons but differ in the number of neutrons.

Compounds

Substances formed by the chemical bonding of two or more elements.

Chemical Bonds

Forces that hold atoms together in a compound.

Ionic Bonds

Bonds formed when electrons are transferred from one atom to another.

Covalent Bonds

Bonds formed when electrons are shared between atoms.

Polar Covalent Bonds

Bonds formed when electrons are shared unequally between atoms.

Non-polar Covalent Bonds

Bonds formed when electrons are shared equally between atoms.

Hydrogen Bonds

Weak chemical bonds that form between hydrogen and an electronegative atom.

Cohesion

The tendency of water molecules to stick to each other.

Adhesion

The tendency of water molecules to stick to other substances.

Capillary Action

The ability of water to rise in narrow spaces.

Surface Tension

The elastic tendency of water surfaces to acquire the least surface area.

Acids

Substances that release hydrogen ions (H+) when dissolved in water.

Bases

Substances that release hydroxide ions (OH–) when added to water.

pH Scale

A scale ranging from 1 to 14 that measures the acidity or alkalinity of a solution.

Organic Molecules

Compounds containing carbon; include carbohydrates, proteins, lipids, and nucleic acids.

Polymers

Chains of monomers that form macromolecules.

Monomers

Individual building blocks that link together to form polymers.

Dehydration Synthesis

The process of forming a polymer by removing a water molecule.

Hydrolysis

The process of breaking down polymers into monomers using water.

Carbohydrates

Organic compounds containing carbon, hydrogen, and oxygen in a 1:2:1 ratio.

Monosaccharides

The simplest carbohydrates; primary energy sources for cells.

Disaccharides

Carbohydrates formed by the union of two monosaccharides.

Polysaccharides

Carbohydrates composed of many monosaccharides.

Glycogen

Storage form of sugar in animals.

Starch

Storage form of sugar in plants.

Cellulose

A polysaccharide that provides structural support in plant cell walls.

Proteins

Polymers made of amino acids, essential for structure and function in organisms.

Amino Acids

Building blocks of proteins.

Peptide Bond

The bond formed between two amino acids.

Polypeptide

A chain of amino acids linked by peptide bonds.

Primary Structure

The linear sequence of amino acids in a protein.

Secondary Structure

The local folding of regions of a polypeptide.

Tertiary Structure

The overall three-dimensional shape of a protein.

Quaternary Structure

The structure formed when multiple polypeptide chains interact.

Lipids

Organic compounds that are important for energy storage and membrane structure.

Triglycerides

Lipids composed of one glycerol and three fatty acid chains.

Phospholipids

Lipids that form cell membranes.

Saturated Fatty Acids

Fatty acids without double bonds between carbon atoms.

Unsaturated Fatty Acids

Fatty acids with one or more double bonds.

Cholesterol

A steroid found in membranes that helps maintain fluidity.

Nucleic Acids

Biomolecules composed of nucleotides, including DNA and RNA.