Chapter 2: The Chemical Level of Organization

Vocabulary flashcards covering chemical principles, elements, atomic structure, bonds, reactions, inorganic/organic compounds, functional groups, macromolecules, enzymes, nucleic acids, and ATP from Chapter 2.

Chemistry

The science of structure and interactions of matter.

Matter

Anything that has mass and takes up space.

Mass

The amount of matter a substance contains.

Weight

The force of gravity acting on a mass.

Major Elements

Chemical elements making up about $96\%$ of total body mass, including oxygen ($65.0\%$), carbon ($18.5\%$), hydrogen ($9.5\%$), and nitrogen ($3.2\%$).

Lesser Elements

Chemical elements contributing about $3.6\%$ of total body mass, including calcium, phosphorus, potassium, sulfur, sodium, chlorine, and magnesium.

Trace Elements

Chemical elements constituting about $0.4\%$ of total body mass, including aluminum, boron, chromium, cobalt, copper, fluorine, iodine, manganese, molybdenum, selenium, silicon, tin, vanadium, and zinc.

Atom

The smallest unit of matter that retains the properties and characteristics of a chemical element.

Atomic Number

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

Mass Number

The total number of protons and neutrons contained in an atom.

Atomic Mass

The average mass of all naturally occurring isotopes of a given chemical element, measured in daltons.

Ion

An atom or molecule that has lost or gained one or more electrons, giving it a positive or negative charge.

Molecule

A combination of two or more atoms sharing electrons.

Compound

A substance that can be broken down into two or more different elements.

Free Radical

An atom or molecule with an unpaired electron in its outermost shell, making it unstable and highly reactive.

Antioxidant

A substance that inactivates oxygen-derived free radicals.

Cation

A positively charged ion, such as $Na^+$ or $K^+$.

Anion

A negatively charged ion, such as $Cl^-$ or $HCO_3^-$.

Ionic Bond

A force of attraction holding together ions with opposite charges.

Covalent Bond

A chemical bond formed when two or more atoms share electrons rather than losing or gaining them.

Hydrogen Bond

A weak attraction resulting from opposite charges between partial positive and negative regions of polar molecules.

Cohesion

The tendency of like particles, such as water molecules, to stay together.

Surface Tension

A measure of the difficulty of stretching or breaking the surface of a liquid.

Reactants

The starting chemical substances in a chemical reaction.

Products

The ending chemical substances produced by a chemical reaction.

Metabolism

The sum of all chemical reactions occurring in the body.

Law of Conservation of Energy

The principle stating that energy can neither be created nor destroyed, but it can be converted from one form to another.

Exergonic Reaction

A chemical reaction that releases more energy than it absorbs.

Endergonic Reaction

A chemical reaction that absorbs more energy than it releases.

Activation Energy

The collision energy required to break existing chemical bonds of reactants so a reaction can begin.

Catalyst

A chemical substance that speeds up a chemical reaction by lowering the required activation energy.

Synthesis Reaction

An anabolic reaction in which two or more atoms, ions, or molecules combine to form new and larger molecules.

Decomposition Reaction

A catabolic reaction in which large molecules are split into smaller atoms, ions, or molecules.

Reversible Reaction

A chemical reaction that can proceed in either direction, where products can revert to original reactants.

Oxidation

The loss of electrons from an atom or molecule during a chemical reaction, releasing energy.

Reduction

The gain of electrons by an atom or molecule during a chemical reaction, gaining energy.

Inorganic Compound

A substance that usually lacks carbon and has simple structural formulas, such as water, salts, acids, and bases.

Organic Compound

A substance that always contains carbon, usually contains hydrogen, and always contains covalent bonds.

Hydrolysis Reaction

A chemical reaction in which a bond in a molecule is broken by the addition of a water molecule.

Dehydration Synthesis Reaction

A chemical reaction in which two smaller molecules join together while removing a water molecule.

Percentage (mass per volume)

A concentration unit representing the number of grams of a solute per $100\,mL$ of solution.

Molarity

A concentration unit defined as the number of moles of a solute per liter ($1\,L$) of solution.

Acid

A substance that dissociates in water into one or more hydrogen ions ($H^+$) and an anion.

Base

A substance that dissociates in water into hydroxide ions ($OH^-$) and a cation, or removes $H^+$ from solution.

Salt

A substance that dissociates in water into cations and anions, neither of which is $H^+$ or $OH^-$.

pH Scale

A scale ranging from 0 to 14 used to measure the relative concentration of hydrogen ions ($H^+$) in a solution.

Buffer Systems

Chemical mechanisms that convert strong acids or strong bases into weak acids or weak bases to regulate pH levels.

Hydroxyl Group

A polar, hydrophilic functional group ($-OH$) found in alcohols.

Sulfhydryl Group

A functional group ($-SH$) found in thiols and cysteine that stabilizes protein structure.

Carbonyl Group

A polar, hydrophilic functional group ($C=O$) present in ketones and aldehydes.

Carboxyl Group

A functional group ($-COOH$ or $-COO^-$) present at one end of all amino acids that acts as an acid.

Phosphate Group

A functional group ($-PO_4^{2-}$) with dual negative charges found in ATP and nucleic acids.

Amino Group

A functional group ($-NH_2$) present at one end of all amino acids that can pick up an $H^+$ to gain a positive charge.

Carbohydrates

Organic compounds composed of carbon, hydrogen, and oxygen (usually in a 2:1 ratio) that function as a primary chemical energy source.

Monosaccharides

Simple sugars containing 3 to 7 carbon atoms, including glucose, fructose, galactose, deoxyribose, and ribose.

Disaccharides

Simple sugars formed by combining two monosaccharides through dehydration synthesis, such as sucrose, lactose, and maltose.

Polysaccharides

Complex carbohydrates made of tens to hundreds of monosaccharides joined by dehydration synthesis, such as glycogen, starch, and cellulose.

Fatty Acids

Molecules with a hydrocarbon chain and carboxyl group used to synthesize triglycerides and phospholipids or catabolized for ATP.

Triglycerides

Lipids consisting of a glycerol molecule and three fatty acid chains, serving in protection, insulation, and energy storage.

Phospholipids

Lipids containing a polar head and nonpolar tails that form the primary framework of cell membranes.

Steroids

Lipids containing four rings of carbon atoms, including cholesterol, bile salts, vitamin D, adrenocortical hormones, and sex hormones.

Eicosanoids

Lipids derived from a 20-carbon fatty acid (prostaglandins and leukotrienes) that modify inflammatory, hormonal, and immune responses.

Amino Acids

Monomers of proteins containing an amino group, a carboxyl group, a hydrogen atom, and a variable side chain ($R$ group).

Peptide Bond

A covalent bond joining the carboxyl group of one amino acid to the amino group of another via dehydration synthesis.

Primary Structure

The specific sequence of amino acids linked by peptide bonds to form a polypeptide chain.

Secondary Structure

The localized twisting and folding of neighboring amino acids into alpha helices or beta pleated sheets, stabilized by hydrogen bonds.

Tertiary Structure

The overall three-dimensional shape of a polypeptide chain.

Quaternary Structure

The spatial arrangement and combination of two or more polypeptide chains in a functional protein.

Enzyme

A highly specific and efficient protein catalyst that increases the rate of chemical reactions in cells.

Active Site

The region on an enzyme where substrate molecules bind to form an enzyme-substrate complex.

DNA (Deoxyribonucleic Acid)

A double-stranded nucleic acid containing deoxyribose sugar that forms the inherited genetic code in cell nuclei.

RNA (Ribonucleic Acid)

A single-stranded nucleic acid containing ribose sugar that carries genetic instructions to synthesize proteins.

ATP (Adenosine Triphosphate)

The principal energy-storing molecule in the body, consisting of adenine, ribose, and three phosphate groups.