Mrs. Sands Biology Ch 06 Biochemistry

atom

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

nucleus

center of an atom; contains neutrons and protons. In eukaryotic cells, the central membrane-bound organelle that manages cellular functions and contains DNA

proton

positively charged particle in an atom's nucleus.

neutron

particle without a charge in an atom's nucleus

electron

negatively charged particle that occupies space around an atom's nucleus.

element

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

isotope

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

compound

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

covalent bond

type of chemical bond formed when atoms share electrons.

molecule

compound whose atoms are held together by covalent bonds

ion

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

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 in substances are changed into different substances

reactant

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

product

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

catalyst

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

enzyme

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

substrate

reactant to which an enzyme binds

active site

specific place where a substrate binds on an enzyme.

polar molecule

molecule with oppositely charged regions

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).

solution

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

solvent

substance in which another substance is dissolved.

solute

substance dissolved in a solvent.

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.

pH

measure of the concentration of hydrogen ions (H+) in a solution.

buffer

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

macromolecule

large molecule formed by joining smaller organic molecules together

polymer

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

carbohydrate

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

lipid

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

protein

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

amino acid

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

nucleic acid

complex macromolecule that stores and communicates genetic information.

nucleotide

a subunit of nucleic acid formed from a single sugar, a phosphate group, and a nitrogenous base.

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