Chemical Context of Life & Molecular Diversity Lecture

Vocabulary flashcards covering key terms from lecture notes on the chemical context of life, water properties, carbon-based molecules, and biological macromolecules.

Matter

Anything that takes up space and has mass.

Element

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

Compound

A substance consisting of two or more different elements combined in a fixed ratio.

Atom

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

Proton

Subatomic particle with one unit of positive charge found in the nucleus.

Neutron

Electrically neutral subatomic particle found in the nucleus.

Electron

Subatomic particle with one unit of negative charge that orbits the nucleus.

Atomic Number

Number of protons in the nucleus of an atom; also equals number of electrons in a neutral atom.

Mass Number

Total number of protons and neutrons in an atom’s nucleus.

Isotope

Atoms of the same element that have different numbers of neutrons.

Radioactive Isotope

Unstable isotope that decays spontaneously, releasing particles and energy.

Potential Energy

Energy that matter possesses because of its location or structure.

Electron Shell

Energy level of electrons at a characteristic average distance from the nucleus.

Valence Electrons

Electrons in the outermost shell that determine chemical behavior.

Covalent Bond

Chemical bond formed by sharing a pair of valence electrons between atoms.

Non-polar Covalent Bond

Covalent bond in which electrons are shared equally between atoms of similar electronegativity.

Polar Covalent Bond

Covalent bond in which electrons are shared unequally, creating partial charges.

Electronegativity

Attraction of an atom for the electrons of a covalent bond.

Ion

Charged atom or molecule resulting from gain or loss of electrons.

Ionic Bond

Attraction between oppositely charged ions.

Hydrogen Bond

Weak attraction between a hydrogen atom carrying partial positive charge and an electronegative atom carrying partial negative charge.

van der Waals Interaction

Weak attraction between molecules or parts of molecules that are close together due to transient local charges.

Cohesion

Linking together of like molecules, often by hydrogen bonds.

Adhesion

Clinging of one substance to a different substance.

Surface Tension

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

Specific Heat

Amount of heat that must be absorbed or lost to change the temperature of 1 g of a substance by 1 °C.

Heat of Vaporization

Quantity of heat a liquid must absorb for 1 g to be converted to gas.

Evaporative Cooling

Cooling of a liquid’s surface that occurs during evaporation, because hottest molecules leave first.

Solution

Liquid that is a homogeneous mixture of two or more substances.

Solvent

Dissolving agent of a solution.

Solute

Substance that is dissolved in a solution.

Hydrophilic

Having an affinity for water.

Hydrophobic

Having no affinity for water; tending to repel or fail to mix with water.

Mole (mol)

Quantity of 6.02 × 10²³ objects; a unit for measuring molecules.

Dalton

Unit of mass equal to 1 atomic mass unit; approximately the mass of one proton or neutron.

pH

Negative logarithm of hydrogen ion concentration; measures acidity or basicity.

Buffer

Substance that minimizes changes in concentrations of H⁺ and OH⁻ in a solution.

Ocean Acidification

Decrease in ocean pH due to absorption of excess atmospheric CO₂ forming carbonic acid.

Hydrocarbon

Organic molecule consisting only of carbon and hydrogen.

Isomer

Compounds with the same molecular formula but different structures and properties.

Structural Isomer

Isomer differing in covalent arrangement of atoms.

Cis-trans Isomer

Isomer with same covalent bonds but different spatial arrangements around a double bond.

Enantiomer

Isomer that is a mirror image of another and cannot be superimposed.

Functional Group

Chemical group attached to carbon skeleton that participates in reactions or affects shape.

ATP (Adenosine Triphosphate)

Primary energy-transfer molecule of the cell, releasing energy when its phosphate bonds are hydrolyzed.

Polymer

Long molecule consisting of many similar or identical monomers linked together.

Monomer

Small building-block molecule that serves as a unit in polymers.

Dehydration Reaction

Reaction in which two monomers are covalently bonded with the loss of a water molecule.

Hydrolysis

Reaction that breaks bonds between monomers by adding water; opposite of dehydration.

Carbohydrate

Sugar or sugar polymer serving as fuel and structural material.

Monosaccharide

Simplest carbohydrate, or simple sugar, with formula multiples of CH₂O.

Disaccharide

Sugar formed from two monosaccharides joined by a glycosidic linkage.

Polysaccharide

Macromolecule composed of many sugar monomers.

Starch

Storage polysaccharide of plants composed of glucose monomers.

Glycogen

Extensively branched glucose storage polysaccharide in animals.

Cellulose

Structural polysaccharide of plant cell walls composed of β-glucose monomers.

Chitin

Structural polysaccharide forming arthropod exoskeletons and fungal cell walls.

Lipid

Hydrophobic biological molecule including fats, phospholipids, and steroids.

Fat (Triacylglycerol)

Lipid composed of glycerol linked to three fatty acids; energy storage.

Saturated Fatty Acid

Fatty acid with no double bonds in hydrocarbon chain; solid at room temperature.

Unsaturated Fatty Acid

Fatty acid with one or more cis double bonds; liquid at room temperature.

Phospholipid

Lipid with glycerol attached to two fatty acids and a phosphate group; forms cell membranes.

Steroid

Lipid characterized by four fused rings; includes cholesterol and hormones.

Protein

Biologically functional molecule composed of one or more polypeptides folded into a specific shape.

Amino Acid

Organic molecule with amino and carboxyl groups, plus a variable side chain; monomer of proteins.

Primary Structure

Linear sequence of amino acids in a polypeptide.

Secondary Structure

Coils and folds (α helix, β sheet) formed by hydrogen bonds within polypeptide backbone.

Tertiary Structure

Overall 3-D shape of a polypeptide stabilized by side-chain interactions.

Quaternary Structure

Protein structure resulting from association of two or more polypeptide subunits.

Denaturation

Loss of a protein’s native shape due to external stress, rendering it inactive.

Nucleic Acid

Polymer of nucleotides; stores and transmits hereditary information (DNA, RNA).

Nucleotide

Monomer of nucleic acids; consists of a nitrogenous base, a pentose sugar, and phosphate group.

DNA (Deoxyribonucleic Acid)

Double-stranded helical nucleic acid containing deoxyribose; stores hereditary information.

RNA (Ribonucleic Acid)

Single-stranded nucleic acid containing ribose; functions in gene expression.

Gene Expression

Process by which DNA directs synthesis of RNA and proteins.

Genomics

Large-scale study of whole sets of genes and their interactions.

Proteomics

Large-scale study of full protein sets (proteomes) encoded by genomes.

Bioinformatics

Application of computational tools to store, organize, and analyze biological data.