Chapter 6 Biology Vocab

nucleotide

a subunit of nucleic acid formed from a simple sugar, a phosphate group, and a nitrogen base.

ion

atom that is negatively or positively charged because it has lost or gained one or more electrons.

van der Waals forces

attractive forces between molecules.

atom

building block of matter; contains subatomic particles: neutrons, protons, and electrons.

nucleus

center of an atom; contains neutrons and protons.

mixture

combination of two or more different substances in which each substance keeps its individual characteristics; can have a uniform composition (homogeneous) or have distinct areas of substances (heterogeneous).

nucleic acid

complex macromolecule that stores and communicates genetic information.

molecule

compound whose atoms are held together by covalent bonds.

ionic bond

electrical attraction between two oppositely charged atoms or groups of atoms.

chemical reaction

energy-requiring process by which atoms or groups of atoms are changed into different substances.

solution

homogeneous mixture formed when a substance (the solute) is dissolved in another substance (the solvent).

lipid

hydrophobic biological molecule composed mostly of carbon and hydrogen; fats, oils, and waxes are lipids.

macromolecule

large molecule formed by joining smaller organic molecules together.

polymer

large molecule formed from smaller repeating units of identical, or nearly identical, compounds linked by covalent bonds.

pH

measure of the concentration of hydrogen ions (H+) in a solution; indicates the relative strength of an acid or a base: an acidic solution has a pH value less than 7, a basic solution has a pH value greater than 7, and pure water is neutral with a pH value

activation energy

minimum amount of energy needed for reactants to form products in a chemical reaction.

buffer

mixture that can react with an acid or a base to maintain the pH within a specific range.

polar molecule

molecule with oppositely charged regions.

electron

negatively charged particle that orbits an atom's nucleus.

carbohydrate

organic compound containing carbon, hydrogen, and oxygen in a ratio of one oxygen and two hydrogen atoms for each carbon atom.

protein

organic compound made of amino acids joined by peptide bonds; primary building block of organisms.

neutron

particle without a charge in an atom's nucleus.

proton

positively charged particle in an atom's nucleus.

enzyme

protein that speeds up a biological reaction by lowering the amount of activation energy needed to start the reaction.

element

pure substance composed of only type of atom; cannot be broken down into another substance by physical or chemical means.

compound

pure substance with unique properties; formed when two or more different elements combine.

substrate

reactant to which an enzyme binds.

amino acid

small carbon compound joined by peptide bonds; building block of proteins.

active site

specific place where a substrate binds on an enzyme.

solute

substance dissolved in a solvent.

product

substance formed by a chemical reaction; located on the right side of the arrow in a chemical equation.

solvent

substance in which another substance is dissolved.

reactant

substance that exists before a chemical reaction starts; located on the left side of the arrow in a chemical equation.

acid

substance that releases hydrogen ions (H+) when dissolved in water; an acidic solution has a pH less than 7.

base

substance that releases hydroxide ions (OH-) when dissolved in water; a basic solution has a pH greater than 7.

catalyst

substance that speeds up a chemical reaction by reducing the needed amount of activation energy.

isotope

two or more atoms of the same element having different numbers of neutrons.

covalent bond

type of chemical bond formed when atoms share electrons.

hydrogen bond

weak electrostatic bond formed by the attraction of opposite charges between a hydrogen atom and an oxygen, fluorine, or nitrogen atom.