The Chemical Basis of Life

Vocabulary practice flashcards covering the chemical basis of life, including atomic structure, chemical bonds, water properties, macromolecules, and enzyme kinetics.

Matter

Anything that occupies space and has mass.

Physical Properties

Characteristics of matter that can be observed without changing its chemical composition, such as size, shape, texture, and hardness.

Volume

The amount of space occupied by matter.

Mass

The amount of matter contained in an object.

Density

The ratio of an object's mass to its volume.

Solid

A physical state of matter with a definite shape and volume, in which molecules are close together and move vibrationally.

Liquid

A physical state of matter that has a definite volume but takes the shape of its container.

Gas

A physical state of matter with no definite shape or volume, where molecules are very far apart and move translationally.

Plasma

A high-energy, charged physical state of matter.

Chemical Properties

Characteristics of matter that allow it to change into new substances, such as the ability to burn, rust, and decompose.

Element

A substance that cannot be broken down into simpler substances by chemical processes.

Atom

The smallest particle of an element that retains the chemical properties of that element.

Compound

A substance formed from two or more different elements linked chemically in definite proportions.

Chemical Formula

A symbolic notation showing the kinds and numbers of atoms present in a substance.

Protons

Positively charged particles with a relatively large mass located inside the atomic nucleus.

Neutrons

Particles with a neutral charge located in the atomic nucleus, possessing about the same mass as a proton.

Electrons

Negatively charged particles with very small mass located outside the nucleus in orbital energy levels.

Atomic Number

The number of protons found in the nucleus of an atom.

Mass Number

The total number of protons plus neutrons in the nucleus of an atom.

Isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Radioactive Isotopes

Isotopes with unstable nuclei that break apart spontaneously; used to study organism chemistry, date artifacts or ancient skeletons, sterilize food, and treat cancer.

Dmitri Mendeleev

The scientist who designed the periodic table by organizing chemical elements based on their properties.

Noble Gases

Elements situated in column $18$ of the periodic table having eight electrons in their outermost energy level.

Average Atomic Mass

The weighted average of the masses of an element's naturally occurring isotopes.

Ionic Bond

A chemical bond formed when ions with opposite charges attract each other, usually when an active metal transfers one or more electrons to a nonmetal.

Ion

An atom that has gained or lost electrons, acquiring an electrical charge.

Covalent Bond

A chemical bond formed when nonmetal atoms share electrons in their outermost energy levels.

Chemical Reaction

A process in which substances are converted into new substances through the breaking and forming of chemical bonds.

Coefficient

A large number placed in front of a chemical symbol or formula that indicates the number of molecules present.

Subscript

A small number following a chemical symbol that specifies the number of atoms of that element.

Endothermic Reaction

A chemical reaction that absorbs energy, where energy is written on the left (reactants) side of the chemical equation.

Exothermic Reaction

A chemical reaction that releases energy (such as cellular respiration releasing heat), where energy is written on the right (products) side of the chemical equation.

Mixture

A combination of substances that are physically blended rather than chemically bonded.

Solution

A uniform, homogeneous mixture of two or more substances.

Solute

The substance that is dissolved in a solution.

Solvent

The dissolving agent or substance that dissolves the solute in a solution.

Suspension

A mixture that includes particles so small that they do not separate and sink.

Polar Molecule

A molecule characterized by an unequal sharing of electrons, giving one end a partial negative charge and the other a partial positive charge.

pH Scale

A measurement standard ranging from $0$ to $14$ by units of ten that measures the concentration of $H^+$ ions in a solution.

Organic Compounds

Most compounds that contain carbon, originally named because they were first extracted from living organisms.

Inorganic Compounds

Compounds that do not contain carbon, with a few exceptions like carbon dioxide ($CO_2$) and carbon monoxide ($CO$).

Functional Groups

Special groups of atoms attached to carbon chains that carry out characteristic chemical reactions.

Monomers

Small organic molecules that serve as building blocks and link together via covalent bonds to form larger molecules.

Polymers

Large molecules formed by chemically linking two or more monomers.

Macromolecules

Giant polymers containing hundreds to thousands of repeating monomers.

Dehydration Synthesis

A chemical reaction that forms a chemical bond between monomers through the removal of a water molecule.

Hydrolysis

A chemical reaction that cleaves covalent bonds between monomers by adding a water molecule.

Cohesion

The attraction between molecules of the same substance.

Adhesion

The attraction between molecules of different substances.

Carbohydrates

Organic compounds composed of carbon, hydrogen, and oxygen in approximately a $1:2:1$ ratio, used for energy and structural support.

Monosaccharides

Simple sugars or simple carbohydrates, such as glucose and fructose, typically containing $3$, $5$, or $6$ carbon atoms.

Disaccharides

Sugars formed when two monosaccharides are linked by covalent bonds via dehydration synthesis, including sucrose, lactose, and maltose.

Polysaccharides

Giant polymers composed of thousands of linked monosaccharides used for fuel, energy storage, and structural support.

Glycogen

A polysaccharide produced by animals from excess sugars and stored in muscles and the liver.

Cellulose

A straight polymer of glucose produced by plants for structural support and food storage, which also serves to regulate the human digestive system.

Chitin

A structural polysaccharide made of modified glucose molecules that composes the exoskeletons of certain animals, used commercially in violin strings and surgical sutures.

Lipids

Water-insoluble, greasy, oily, or waxy compounds composed mainly of carbon, hydrogen, and oxygen (and sometimes phosphorus).

Saturated Fat

A fat containing the maximum number of hydrogen atoms bonded to carbon atoms exclusively through single bonds.

Unsaturated Fat

A fat lacking the maximum number of hydrogens due to the presence of one or more carbon-carbon double bonds.

Phospholipids

Phosphorus-containing lipids that serve as the major structural component of cell membranes.

Steroids

Lipids composed of four interconnected carbon rings, functioning as hormones or structural membrane components like cholesterol.

Waxes

Waterproofing lipid compounds composed of fatty acids linked to certain alcohols.

Proteins

Essential macromolecules composed of carbon, hydrogen, oxygen, nitrogen, and sulfur that form polymers of amino acids.

Amino Acid

The monomer building block of proteins, composed of an amino group, a carboxyl group, and a variable side chain ($R$ group).

Enzymes

Catalytic proteins that speed up the chemical reactions of a cell by lowering the activation energy without being changed.

Active Site

The specific region on an enzyme where the substrate attaches and the chemical reaction occurs.

Substrate

The specific reactant molecule that binds to an enzyme in an enzymatic reaction.

Nucleotide

The monomer of nucleic acids, consisting of a five-carbon sugar, a nitrogen-containing base, and a phosphate group.

DNA (Deoxyribonucleic Acid)

A double-stranded nucleic acid containing deoxyribose sugar and bases $A, T, C, G$ that stores and transfers hereditary information controlling protein synthesis.

RNA (Ribonucleic Acid)

A single-stranded nucleic acid containing ribose sugar and bases $A, U, C, G$ that acts as a messenger between DNA and ribosomes to direct protein synthesis.