Chapter 2 Lecture: The Chemical Elements, Water, Energy, Monomers, Polymers, and Macromolecules

A complete list of vocabulary flashcards covering chemical elements, atomic structure, bonds, water, pH, macromolecules, proteins, and nucleic acids.

Element

The simplest form of matter to have unique chemical properties.

Atomic number

The number of protons in the nucleus of an element.

Minerals

Inorganic elements extracted from soil by plants and passed up the food chain to humans, constituting about $4\%$ of body weight.

Electrolytes

Substances that ionize in water and form solutions capable of conducting electric current.

Valence electrons

Electrons that orbit in the outermost shell and determine the chemical bonding properties of an atom.

Ion

A charged particle (atom or molecule) with an unequal number of protons and electrons.

Anion

A particle that gains electron(s), acquiring a net negative charge (e.g., $Cl^-$).

Cation

A particle that loses electron(s), acquiring a net positive charge (e.g., $Na^+$).

Molecule

A chemical particle composed of two or more atoms united by a chemical bond.

Compound

A molecule composed of two or more different elements.

Isomers

Molecules with identical molecular formulae but a different arrangement of their atoms.

Ionic bonds

Attractions between anions and cations due to charge difference, formed when valence electrons are donated from one atom to another.

Covalent bonds

Bonds formed when shared electrons spend time orbiting around different nuclei due to attraction of the nucleus to partially fill a shell.

Hydrogen bond

A weak attraction between a slightly positive hydrogen atom in one molecule and a slightly negative oxygen or nitrogen atom in another.

Hydrophilic

Refers to substances that dissolve in water, requiring molecules to be polarized or charged.

Hydrophobic

Refers to substances that do not dissolve in water because their molecules are nonpolar or neutral.

Adhesion

The tendency of one substance to cling to another.

Cohesion

The tendency of like molecules to cling to each other.

Heat capacity

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

Acid

A proton donor that releases $H^+$ ions in water.

Base

A proton acceptor that accepts $H^+$ ions and often releases $OH^-$.

pH

A measure derived from the molarity of $H^+$ ($[H^+]$) on a logarithmic scale, defined as $pH = -\log[H^+]$.

Buffers

Chemical solutions that resist changes in pH.

Potential energy

Energy stored in an object that is not currently doing work.

Kinetic energy

Energy of motion that is doing work.

Polymers

Macromolecules made of a repetitive series of identical or similar subunits called monomers.

Dehydration synthesis (condensation)

A process where living cells form polymers by removing a hydroxyl ($-OH$) group from one monomer and a hydrogen ($-H$) from another, producing water as a by-product.

Hydrolysis

A digestion process that splits a polymer into monomers by the addition of a water molecule.

Glycogen

A polysaccharide that provides energy storage in cells of the liver, muscle, brain, uterus, and vagina.

Starch

An energy storage polysaccharide in plants that is digestible by humans.

Cellulose

A structural polysaccharide in plants that serves as human dietary fiber and is indigestible to humans.

Saturated fatty acids

Fatty acids that contain a lot of hydrogen with only single bonds between carbon atoms in the chain.

Unsaturated fatty acids

Fatty acids that contain some double bonds between carbon atoms in the chain.

Trans-fatty acids

Fatty acids in which two covalent single $C-C$ bonds angle in opposite directions on each side of a $C=C$ double bond.

Phospholipids

Molecules similar to neutral fats except one fatty acid is replaced by a phosphate group, forming the structural foundation of cell membranes.

Eicosanoids

20-carbon lipid compounds derived from arachidonic acid that act as hormone-like chemical signals between cells.

Steroid

A lipid characterized by 17 carbon atoms arranged in four rings.

Cholesterol

The parent steroid from which other steroids are synthesized, with $15\%$ obtained from diet and $85\%$ internally synthesized.

Amino acid

A monomer of protein consisting of a central carbon attached to an amino group ($NH_2$), a carboxyl group ($-COOH$), and a radical ($R$) group.

Peptide bond

A covalent bond formed by dehydration synthesis that joins the amino group of one amino acid to the carboxyl group of another.

Conformation

The unique, three-dimensional shape of a protein crucial to its function.

Denaturation

An extreme conformational change in a protein caused by extreme heat or pH that destroys its function.

Primary structure

A protein's sequence of amino acids encoded in the genes.

Secondary structure

The coiled or folded shape of a protein held together by hydrogen bonds.

Tertiary structure

The further bending and folding of proteins into globular and fibrous shapes due to hydrophobic-hydrophilic interactions and van der Waals forces.

Quaternary structure

The association of two or more polypeptide chains held together by ionic bonds and hydrophobic-hydrophilic interactions.

Adenosine Triphosphate (ATP)

The body's most important energy-transfer nucleotide composed of adenine, ribose, and three phosphate groups.

Phosphorylation

The addition of a free phosphate group to a molecule.

Kinases

Enzymes that carry out phosphorylation by adding free phosphate groups to molecules.

DNA (deoxyribonucleic acid)

A nucleic acid polymer containing millions of nucleotides that constitutes genes and provides instructions for synthesizing proteins.

RNA (ribonucleic acid)

A nucleic acid polymer 70 to 10,000 nucleotides long that carries out genetic instructions for synthesizing proteins and assembles amino acids in the right order.