Chemical Basis of Life - Comprehensive Study Guide

Vocabulary flashcards defining key chemistry concepts, subatomic particles, chemical bonds, reactions, inorganic molecules, and organic macromolecules from Chapter 2.

Chemistry

The science that deals with the composition and characteristics of chemicals.

Matter

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

Elements

The smallest units of matter with specific chemical properties.

Atom

The smallest unit of an element.

Protons

Positively charged subatomic particles located in the atomic nucleus that are about equal in size to neutrons.

Neutrons

Uncharged subatomic particles located within the nucleus of an atom.

Electrons

Negatively charged subatomic particles that are much smaller than protons and neutrons and orbit the nucleus in shells.

Ions

Atoms that have gained or lost one or more electrons and become electrically charged.

Atomic Number

The number of protons in the atoms of a specific element.

Atomic Weight

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

Isotopes

Atoms that have the same atomic number but different atomic weights due to varying numbers of neutrons.

Ionic Bond

A chemical bond formed by the attraction between oppositely charged ions.

Covalent Bond

A chemical bond formed when atoms share pairs of electrons to fill their outermost shells.

Polar Molecule

A molecule with an unequal charge distribution resulting from polar covalent bonds in which electrons are not shared equally.

Hydrogen Bond

A relatively weak attraction between the slightly positive hydrogen end of a polar molecule and the slightly negative nitrogen or oxygen end of a nearby polar molecule.

Molecule

A particle formed when two or more atoms combine through chemical bonding.

Compound

A substance formed when atoms of different elements combine in definite types and numbers.

Molecular Formula

A representation showing the numbers and types of atoms present in a molecule, such as $C_6H_{12}O_6$ for glucose or $H_2O$ for water.

Reactants

The starting substances that are changed by a chemical reaction.

Products

The substances formed as a result of a chemical reaction.

Synthesis Reaction

A chemical reaction in which two or more atoms or molecules bond together to form a more complex product.

Decomposition Reaction

A chemical reaction in which larger molecules are broken down into smaller ones by breaking chemical bonds.

Exchange Reaction

A chemical reaction in which parts of molecules trade places by breaking chemical bonds and forming new ones.

Reversible Reaction

A chemical reaction in which the products can change back into the reactants, symbolized by double arrows.

Catalysts

Molecules that influence the speed of chemical reactions without being consumed in the process; in the body, these are called enzymes.

Electrolytes

Substances that release ions in water and are capable of carrying an electric charge in the body.

Acids

Electrolytes that release hydrogen ions ($H^+$) in water.

Bases

Electrolytes that release ions that combine with hydrogen ions in water.

pH

A system that represents the concentration of hydrogen ions ($[H^+]$) in a solution on a scale running from $0$ to $14$.

Buffers

Chemicals that combine with excess acids or bases to help minimize pH changes in body fluids.

Organic Compounds

Molecules that contain both carbon and hydrogen atoms, many of which are nonelectrolytes that dissolve in water without releasing ions.

Inorganic Compounds

Chemical compounds that generally do not contain both carbon and hydrogen, usually dissolve in water, and release ions to act as electrolytes.

Solvent

A liquid substance, such as water, in which other substances (solutes) dissolve.

Carbohydrates

Organic compounds composed of carbon, hydrogen, and oxygen that provide energy for cellular activities and materials for cell structures.

Monosaccharides

The smallest carbohydrate building blocks containing $5$ to $6$ carbon atoms, such as glucose, fructose, galactose, ribose, and deoxyribose.

Disaccharides

Double sugars consisting of two simple sugars joined together, such as lactose, sucrose, and maltose.

Polysaccharides

Complex carbohydrates consisting of many simple sugar molecules joined together, such as glycogen and starch.

Lipids

Organic substances that are insoluble in water, including triglycerides, phospholipids, and steroids.

Triglycerides

The most abundant lipids in the body, consisting of one glycerol molecule bound to three fatty acid chains, which store and supply energy.

Saturated Fatty Acid

A fatty acid molecule containing only single bonds between carbon atoms.

Unsaturated Fatty Acid

A fatty acid molecule that contains one or more double bonds between carbon atoms.

Phospholipids

Lipids consisting of a glycerol molecule, two fatty acid chains, and a phosphate group, serving as major structural components of cell membranes.

Steroids

Complex lipid molecules containing four connected rings of carbon atoms, including cholesterol and certain hormones.

Proteins

Organic compounds containing carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur, which carry out structural, enzymatic, and regulatory functions.

Amino Acids

The building blocks of proteins, each containing an amino group ($-NH_2$), a carboxyl group ($-COOH$), and a variable side chain ($R$\text{ group}).

Primary Structure

The specific linear sequence of amino acids in a polypeptide chain.

Secondary Structure

The pleated or twisted coil structure of a protein resulting from hydrogen bonds between amino acids.

Tertiary Structure

The unique three-dimensional folded shape of a protein resulting from attractions between amino acids in different parts of the molecule.

Quaternary Structure

The level of protein structure formed when two or more polypeptide chains combine into a single larger molecule.

Conformation

The unique three-dimensional shape of a protein that determines its biological function.

Denaturation

The irreversible disruption of a protein's shape and loss of function caused by breaking hydrogen bonds due to factors like pH changes or excessive temperature.

Nucleic Acids

Large organic molecules composed of nucleotide chains that store genetic information and participate in protein synthesis.

Nucleotide

The building block of nucleic acids, consisting of a $5$-carbon sugar, a phosphate group, and a nitrogenous base.

RNA (Ribonucleic Acid)

A single-stranded nucleic acid containing ribose sugar that functions in protein synthesis.

DNA (Deoxyribonucleic Acid)

A double-stranded nucleic acid twisted into a spiral that contains deoxyribose sugar and stores the molecular genetic code in genes.

Adenosine Triphosphate (ATP)

A modified RNA nucleotide containing three phosphate groups that stores and provides energy for chemical reactions in the body.