An Introduction to the Chemical Level of Organization

Vocabulary flashcards covering key terms and concepts in chemical structures, atomic structure, bonds, reactions, organic and inorganic compounds, proteins, lipids, carbohydrates, nucleic acids, and energy compounds.

Chemistry

The science that deals with the structure of matter, including the structure of atoms, basic chemical building blocks, and how atoms combine to form increasingly complex structures.

Matter

Anything that takes up space and has mass.

Protons

Subatomic particles with a positive charge and a mass of 1 mass unit.

Neutrons

Subatomic particles that are neutral and have a mass of 1 mass unit.

Electrons

Subatomic particles with a negative charge and low mass.

Atomic number

The number of protons in an atom, which determines its chemical properties.

Mass number

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

Isotopes

Versions of elements based on differing mass numbers.

Radioisotopes

Isotopes with radioactive nuclei whose decay rate is expressed as a half-life.

Mole (mol)

A quantity of an element that has a weight in grams equal to its atomic weight.

Valence shell

The outermost electron shell of an atom, which determines its chemical bonding.

Molecule

Two or more atoms joined together by strong bonds.

Compound

Two or more atoms of different elements joined by strong or weak bonds.

Cation

An ion with a positive charge formed when an electron donor atom loses one or more electrons.

Anion

An ion with a negative charge formed when an electron acceptor atom gains one or more electrons.

Ionic bonds

Attractions between cations (positive ions) and anions (negative ions).

Covalent bonds

Strong chemical bonds involving shared electrons between atoms.

Nonpolar covalent bonds

Covalent bonds featuring equal sharing of electrons between atoms that have equal pull.

Polar covalent bonds

Covalent bonds featuring unequal sharing of electrons because one atom has a disproportionately strong pull on the electrons.

Hydrogen bonds

Weak polar bonds between adjacent molecules based on electrical attractions between a slight positive charge and a slight negative charge.

Metabolism

All of the chemical reactions that are occurring in the body at one time.

Kinetic energy

The energy of motion.

Potential energy

Stored energy.

Decomposition reaction

A chemical reaction that breaks chemical bonds, represented as $\text{AB} \rightarrow \text{A} + \text{B}$.

Hydrolysis reaction

A decomposition reaction involving water, represented as $\text{AB} + \text{H}_2\text{O} \rightarrow \text{AH} + \text{BOH}$.

Synthesis reaction

A chemical reaction that forms chemical bonds, represented as $\text{A} + \text{B} \rightarrow \text{AB}$.

Dehydration synthesis

A synthesis reaction that forms complex molecules by removing water, represented as $\text{AH} + \text{BOH} \rightarrow \text{AB} + \text{H}_2\text{O}$.

Activation energy

The amount of energy needed to start a chemical reaction.

Enzymes

Protein catalysts that lower the activation energy of chemical reactions.

Exergonic reactions

Reactions that release energy.

Endergonic reactions

Reactions that absorb energy.

Inorganic compounds

Molecules that lack carbon-hydrogen frameworks, such as carbon dioxide, oxygen, water, and inorganic acids, bases, and salts.

Organic compounds

Molecules containing carbon and hydrogen, including carbohydrates, proteins, lipids, and nucleic acids.

Heat capacity

The heat required to raise the temperature of a unit mass of a substance by $1\,^{\circ}\text{C}$.

Ionization

The dissociation of inorganic compounds into ions in water.

Hydration spheres

Structures formed by polar water molecules surrounding ions and small polar molecules to keep them in solution.

Electrolytes

Inorganic ions that conduct electricity in solution.

Hydrophilic

Molecules (meaning 'water-loving'), including ions and polar molecules, that interact readily with water.

Hydrophobic

Molecules (meaning 'fear'), including nonpolar molecules, fats, and oils, that do not interact with water.

Colloid

A solution containing dispersed proteins or other large molecules, such as blood plasma.

Suspension

A mixture containing large particles that settle out of solution if left undisturbed, such as whole blood.

pH

The negative logarithm of the hydrogen ion concentration of a solution in moles per liter.

Acid

A solute (proton donor) that adds hydrogen ions to a solution.

Base

A solute (proton acceptor) that removes hydrogen ions from a solution.

Salt

An ionic solute that dissociates into cations and anions other than hydrogen ions and hydroxide ions.

Buffers

Compounds or systems that stabilize the pH of solutions by neutralizing strong acids or strong bases.

Isomers

Molecules that share the same molecular formula but have different structural arrangements.

Monosaccharides

Simple sugars containing three to seven carbon atoms, such as glucose, fructose, and galactose.

Disaccharides

Two monosaccharides joined together by dehydration synthesis, such as sucrose and maltose.

Polysaccharides

Complex polymers of many sugars condensed by dehydration synthesis, such as glycogen, starch, and cellulose.

Fatty acids

Long chains of carbon and hydrogen with a carboxyl group ($-\text{COOH}$) at one end.

Saturated fatty acid

A fatty acid whose hydrocarbon tail contains only single covalent bonds between carbon atoms.

Unsaturated fatty acid

A fatty acid containing one or more double bonds in its hydrocarbon tail.

Eicosanoids

Lipids derived from arachidonic acid that must be obtained from the diet, including leukotrienes and prostaglandins.

Triglycerides

Neutral fats consisting of a glycerol molecule attached to three fatty acids that function in energy storage, insulation, and protection.

Steroids

Lipids characterized by a complex four-ring carbon structure, including cholesterol, sex hormones, corticosteroids, calcitriol, and bile salts.

Micelles

Droplets formed in water by phospholipids and glycolipids, with hydrophilic heads facing the water and hydrophobic tails on the inside.

Peptide bond

A covalent bond formed via dehydration synthesis between the amino group of one amino acid and the carboxyl group of another.

Primary structure

The linear sequence of amino acids along a polypeptide chain.

Secondary structure

Protein structural shape resulting from hydrogen bonding along the polypeptide chain, producing an alpha helix or beta sheet.

Tertiary structure

The three-dimensional shape of a protein created by complex coiling and folding of a single polypeptide chain.

Quaternary structure

The final protein complex formed by the interaction of separate polypeptide subunits.

Denaturation

A change in protein shape and loss of biological function caused by extreme heat or pH.

Nucleotides

Monomers of nucleic acids consisting of a pentose sugar, a phosphate group, and a nitrogenous base.

Purines

Double-ring nitrogenous bases, specifically adenine and guanine.

Pyrimidines

Single-ring nitrogenous bases, including cytosine, thymine (DNA only), and uracil (RNA only).

Phosphorylation

The process of attaching a phosphate group to another molecule, forming a high-energy bond.

Adenosine triphosphate (ATP)

A high-energy compound consisting of adenosine bonded to three phosphate groups.