Biochemistry and General Chemistry Vocabulary

Comprehensive vocabulary flashcards covering general chemistry, chemical bonding, water properties, organic compounds, and biological macromolecules based on lecture notes.

Matter

Anything that takes up space and has mass.

Element

A substance that cannot be broken down to other substances by chemical reactions.

Essential Elements

The elements an organism needs to live a healthy life and reproduce, constituting about $20\text{ to }25\text{\%}$ of the $92$ natural elements.

Trace Elements

Elements required by organisms in only minute quantities, making up less than $0.01\text{\%}$ of body mass.

Atom

The smallest unit of matter that still retains the unique properties of an element.

Atomic Number

The unique number of protons contained within the nucleus of an atom of a specific element.

Mass Number

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

Isotope

One of several atomic forms of an element with the same number of protons but a different number of neutrons.

Radioactive Isotope

An unstable isotope whose nucleus decays spontaneously, emitting subatomic particles and energy.

Valence Electrons

Electrons located in the outermost electron shell of an atom that are available to participate in chemical bonding.

Covalent Bond

A strong chemical bond formed when two atoms share a pair of valence electrons.

Electronegativity

The attraction or pulling force that a particular atom exerts on the shared electrons of a covalent bond.

Nonpolar Covalent Bond

A covalent bond formed between two atoms with similar electronegativities, resulting in equal sharing of electrons.

Polar Covalent Bond

A covalent bond between atoms that differ in electronegativity, leading to an unequal sharing of electrons and partial electrical charges.

Ionic Bond

A chemical attraction resulting from the mutual attraction between oppositely charged ions.

Cation

A positively charged ion formed when an atom loses one or more valence electrons.

Anion

A negatively charged ion formed when an atom gains one or more valence electrons.

Hydrogen Bond

A weak noncovalent attraction between a hydrogen atom carrying a partial positive charge and an electronegative atom.

Chemical Equilibrium

The state in a reversible chemical reaction where the forward and reverse reaction rates are equal, keeping reactant and product concentrations constant.

Cohesion

The binding together of like molecules, such as hydrogen bonds holding water molecules tightly to one another.

Adhesion

The clinging of one substance to a different substance, such as water adhering to plant cell walls.

Surface Tension

A measure of how difficult it is to stretch or break the surface of a liquid.

Specific Heat

The amount of heat that must be absorbed or lost for $1\,g$ of a substance to change its temperature by $1\,^\circ\text{C}$.

Heat of Vaporization

The quantity of heat a liquid must absorb for $1\,g$ of it to be converted from a liquid state to a gaseous state.

Evaporative Cooling

The process in which the surface of an object becomes cooler during evaporation as the molecules with the greatest kinetic energy escape as gas.

Hydrophilic

Describing any substance that has a strong chemical affinity for water.

Hydrophobic

Describing nonionic or nonpolar substances that have no affinity for water and tend to repel it.

Buffer

A substance that minimizes changes in the concentration of $H^+$ and $OH^-$ in a solution to maintain a stable pH.

Organic Compound

A chemical compound containing the element carbon.

Macromolecules

Large complex organic molecules in living organisms divided into carbohydrates, lipids, proteins, and nucleic acids.

Hydrocarbon

An organic nonpolar molecule consisting exclusively of carbon and hydrogen atoms.

Functional Group

A specific configuration of atoms attached to an organic molecule's carbon skeleton that is directly involved in chemical reactions.

Polymer

A long molecule consisting of many similar or identical building blocks linked together by covalent bonds.

Monomer

The repeating molecular unit that serves as the essential building block for a polymer.

Dehydration Reaction

A chemical reaction in which two monomers become covalently bonded with the concomitant loss of a water molecule ($H_2O$).

Hydrolysis

A biological process that breaks covalent bonds between monomers through the addition of a water molecule ($H_2O$).

Monosaccharide

The simplest carbohydrate monomer, having a formula that is a multiple of $CH_2O$ (e.g., glucose, $C_6H_{12}O_6$).

Disaccharide

A double sugar consisting of two monosaccharides joined by a covalent glycosidic linkage.

Glycosidic Linkage

A covalent bond formed between two monosaccharide units by a dehydration reaction.

Polysaccharide

A polymer of hundreds to thousands of monosaccharides joined together by glycosidic linkages.

Starch

A storage polysaccharide in plants composed entirely of glucose monomers linked together.

Glycogen

An extensively branched glucose storage polysaccharide stored in liver and muscle tissue of animals.

Cellulose

An unbranched structural polysaccharide composed of glucose monomers that forms plant cell walls.

Chitin

A structural polysaccharide found in the exoskeletons of arthropods and the cell walls of fungi.

Lipids

A group of biological compounds unified by their insolubility in water due to nonpolar hydrocarbon structures.

Fat

A lipid molecule composed of a single glycerol molecule attached to three fatty acid tails via ester linkages; also termed triacylglycerol.

Saturated Fat

A fat in which all carbons in the hydrocarbon tail are connected by single bonds, allowing linear chains to pack closely as a solid at room temperature.

Unsaturated Fat

A fat containing one or more carbon-carbon double bonds, which creates kinks in the hydrocarbon chains preventing tight packing and keeping it liquid at room temperature.

Phospholipid

An amphiphilic lipid composed of glycerol joined to two hydrophobic fatty acid tails and one hydrophilic phosphate head group.

Steroid

A lipid molecule characterized by a carbon skeleton consisting of four fused rings, such as cholesterol.

Amino Acid

An organic molecule containing a central alpha carbon ($\alpha\text{-carbon}$) attached to an amino group, a carboxyl group, a hydrogen atom, and a variable side chain ($R$ group).

Polypeptide

An unbranched polymer of amino acids linked together by peptide bonds.

Peptide Bond

The covalent bond linking the carboxyl end of one amino acid to the amino group of another via a dehydration reaction.

Primary Structure

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

Secondary Structure

Local coils and folds in a polypeptide chain held together by hydrogen bonds along the backbone, such as $\alpha$ helices and $\beta$ pleated sheets.

Tertiary Structure

The overall three-dimensional shape of a polypeptide chain determined by interactions among amino acid side chains ($R$ groups).

Quaternary Structure

The overall protein structure that results when two or more individual polypeptide chains aggregate into one functional macromolecule.

Denaturation

A process in which a protein unfolds and loses its native functional shape due to disruptions in weak bonds caused by changes in pH, temperature, or salt concentration.

Nucleic Acid

A biological polymer composed of nucleotide monomers that enables organisms to reproduce their genetic components (DNA and RNA).

Nucleotide

The monomer of a nucleic acid, consisting of a five-carbon pentose sugar, a nitrogenous base, and one to three phosphate groups.

Pyrimidine

A nitrogenous base possessing a single six-membered ring of carbon and nitrogen atoms (Cytosine, Thymine, Uracil).

Purine

A nitrogenous base possessing a six-membered ring fused to a five-membered ring (Adenine, Guanine).

Deoxyribose

The pentose sugar component found in DNA nucleotides, which lacks an oxygen atom on the second carbon ring relative to ribose.

Ribose

The pentose sugar component found in RNA nucleotides.

Antiparallel

The structural orientation in a DNA double helix where the two sugar-phosphate backbones run in opposite $5' \rightarrow 3'$ directions.