AP Biology Vocabulary

Unit 1 Chapter 2

Matter - anything that takes up space and has mass

Element - any substance that cannot be broken down to any other substance by chemical reactions

Compound - a substance consisting of two or more different elements combined to a fixed ratio

Isotope - one of several atomic forms of an element, each with the same number of protons but a different number of neutrons, thus differing in atomic mass

Valence Electron - an electron in the outermost electron shell

Electronegativity - the attraction of a given atom for the electrons of a covalent bond

Nonpolar Covalent Bond - a type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity

Polar Covalent Bond - a covalent bond between atoms that differ in electronegativity; the shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive

London Dispersion Forces - also known as Van der Waals forces, are weak intermolecular forces that arise from temporary fluctuations in electron distribution within atoms and molecules; these forces are present in all molecules, whether polar or nonpolar, and are the only type of intermolecular force acting between nonpolar molecules

Ionic Bond - a chemical bond resulting from the attraction between oppositely charged ions

Hydrogen Bond - a type of weak chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule or in another region of the same molecule

Van der Waals Interactions - weak attractions between molecules or parts of molecules that result from transient local partial charges

Reactants - a starting material in a chemical reaction

Products - a material resulting from a chemical reaction

Cohesion - the linking together of like molecules, often by hydrogen bonds

Adhesion - the clinging of one substance to another, such as water to plant cell walls

Specific Heat - the amount of heat that must be absorbed or lost for 1g of a substance to change its temperature by 1 degree C

Tetrahedral -

Hydrophobic - having no affinity for water; tending to coalesce and form droplets in water

Hydrophilic - having an affinity for water

Solute - a substance that is dissolved in a solution

Solvent - the dissolving agent of a solution

Molarity - a common measure of solute concentration, referring to the number of moles of solute per liter of solution

Atomic Number - the number of protons in the nucleus of an atom, unique for each element and designated by a subscript

pH - a measure of hydrogen ion concentration equal to the negative log of the concentration of hydrogen ions and ranging in value from 0 to 14

Buffer - a solution that contains a weak acid and its corresponding base; minimizes changes in pH when acids or bases are added to the solution

Surface Tension - a measure of how difficult it is to stretch or break the surface of a liquid

Solution - a liquid that is a homogeneous mixture of two or more substances

Evaporative Cooling - the process in which the surface of an object becomes cooler during evaporation, a result of the molecules with the greatest kinetic energy changing from the liquid to the gaseous state

Acid - a substance that increases the hydrogen ion concentration of a solution

Base - a substance that reduces the hydrogen ion concentration of a solution

Anion - a negatively charged ion

Cation - a positively charged ion

Radioactive Isotopes - atoms with unstable nuclei that decay spontaneously, emitting particles and energy; can transform the atom into a different element

Carbon Dating - a method used to determine the age of fossils and archaeological specimens, relies on the decay of the radioactive isotope carbon-14 and nitrogen-14

Mole - the number of grams of a substance that equals its molecular weight in Daltons and contains Avogadro’s number of molecules

Unit 1 Chapter 3

Hydrocarbons - an organic molecule consisting of only carbon and hydrogen

Polymer - a long molecule consisting of many similar or identical monomers linked together by covalent bonds

Monomer - the subunit that serves as the building block of a polymer

Dehydration Reaction - a chemical reaction in which two molecules become covalently bonded to each other with the removal of a water molecule

Hydrolysis - a chemical reaction that breaks bonds between two molecules by the addition of water: functions in disassembly of polymers to monomers

Monosaccharides - the simplest carbohydrate, active alone or serving as a monomer for disaccharides and polysaccharides; also known as simple sugars

Polysaccharides - a polymer of many monosaccharides, formed by dehydration reactions

Disaccharides - a double sugar, consisting of two monosaccharides joined by a glycosidic linkage formed by a dehydration reaction

Glycosidic Linkage - a covalent bond formed between two monosaccharides by a dehydration reaction

Catalyst - a chemical agent that selectively increases the rate of reaction without being consumed by the reaction

Polypeptide - a polymer of many amino acids linked together by peptide bonds

Peptide Bond - the covalent bond between the carboxyl group on one amino acid and the amino group on another, formed by a dehydration reaction

Alpha Helix - a region of a protein that twists into a tight spiral, resembling a coiled spring; stabilized by hydrogen bonds between nearby amino acids, stabilizing the helix’s shape

Beta Pleated Sheet - a type of secondary structure found in proteins, characterized by its sheet-like arrangement, where polypeptide chains lie parallel or antiparallel to each other, forming a pleated appearance; stabilized by hydrogen bonds between the backbone atoms of the polypeptide chains

Primary Structure - the linear sequence of amino acids in a polypeptide chain, determined by the genetic code in DNA; dictates the protein’s higher-level structures and functions

Secondary Structure - the local folded structures that form within a polypeptide due to interactions between atoms of the backbone, two most common types are alpha helix and beta pleated sheet

Tertiary Structure - a protein’s overall three-dimensional shape, which is crucial for function; formed by interactions between side chains (R groups) of the amino acids in the polypeptide chain

Quaternary Structure - the overall structure formed when multiple polypeptide chains, known as subunits, come together to form a function protein; crucial for proteins that consist of more than one polypeptide chain

Disulfide Bridge - a strong covalent bond formed between two sulfur atoms, typically from the side chains of cysteine amino acids within a protein; these play a crucial role in stabilizing the protein’s tertiary and quaternary structures

Denaturation - in proteins, a process in which a protein loses its native shape due to the disruption of weak chemical bonds and interactions, thereby becoming biologically inactive; in DNA, the separation of the two strands of the double helix; occurs under extreme (noncellular) conditions of pH, salt concentration, or temperature

Nucleotides - the building blocks of a nucleic acid, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and one to three phosphate groups

Steroid - a type of liquid characterized by a carbon skeleton consisting of four fused rings with various chemical groups attached

ATP - an adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed; this energy is used to drive endergonic reactions in cells

Antiparallel - refers to the arrangement of the sugar-phosphate backbone in a DNA double helix

DNA (deoxyribonucleic acid) - a nucleic acid molecule, usually a double-stranded helix, in which each polynucleotide strand consists of nucleotide monomers with a deoxyribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T); capable of being replicated and determining the inherited structure of a cell’s proteins

RNA (ribonucleic acid) - a type of nucleic acid consisting of a polynucleotide made up of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; functions in protein synthesis, gene regulation, and as the genome of some viruses

Pyrimidine - one of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring: cytosine (C), thymine (T), and uracil (U)

Purines - one of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring fused to a five-membered ring: adenine (A) and guanine (G)