Term | Definition |
matter | anything that occupies space and has mass |
mass | quantity of matter an object has |
element | substances that cannot be broken down chemically into simpler kinds of matter |
atom | simplest particle of an element that retain all of the properties of that element |
nucleus | makes up the bulk of the mass of the atom and consists of two kinds of subatomic particles |
proton | makes up the nucleus, is positively charged |
neutron | makes up the nucleus, has no charge |
atomic number | the number of protons in an element |
mass number | equal to the total number of protons and neutrons of the atom |
electron | small negatively charged particles |
orbital | a three-dimensional region around a nucleus that indicates the probable location of an electron |
isotope | atoms of the same element that have different number of neutrons |
compound | made up of atoms of two or more elements in fixed proportions |
chemical bond | attractive forces that hold atoms together |
covalent bond | forms when two atoms share one of more pairs of electrons |
molecule | simplest part of a substance that retains all of the properties of that substance and can exist in a free state |
ion | an atom or molecule with an electrical charge |
ionic bond | the attractive force between oppositely charged ions, which form when electrons are transferred from one atom to another |
organic compound | made primarily of carbon atoms |
functional groups | influence the characteristics of the molecules they compose and the chemical reactions the molecules undergo |
monomer | a simple molecule that can combine with other like or unlike molecules to make a polymer |
polymer | molecule that consists of repeated, linked units |
macromolecule | large polymers |
condensation reaction | monomers link to form polymers through chemical reaction |
hydrolysis | water is used to break down a polymer |
adenosine triphosphate (ATP) | one type of compound that stores a large amount of energy in their overall structure |
carbohydrate | organic compounds composed of carbon, hydrogen, and oxygen in a ratio of about one atom to two hydrogen atoms to one oxygen atom |
monosaccharide | a monomer of a carbohydrate |
disaccharide | two monosaccharides can combine in a condensation reaction to form a double sugar |
polysaccharide | complex molecule composed of three or more monosaccharides |
protein | organic compounds composed mainly of carbon, hydrogen, oxygen, and nitrogen |
amino acid | proteins are formed from the linkage of monomers |
peptide bond | two amino acids form a covalent bond |
polypeptide | amino acids often form very long chains |
enzyme | RNA or protein molecules that act as biological catalysts are essential for the functioning of any cell. |
substrate | a part, substance, or element that lies beneath and supports another part, substance, or element; the reactant in reactions catalyzed by enzymes |
active site | the site on an enzyme that attaches to a substrate |
lipid | large, non polar organic molecules, do not dissolve in water |
deoxyribonucleic acid (DNA) | contains information that determines the characteristics of an organism and directs its cell activities |
ribonucleic acid (RNA) | stores and transfers information from DNA that is essential for the manufacturing of proteins |
nucleotide | made of three main components: phosphate group, a five-carbon sugar, and a ring-shaped nitrogenous base |
fatty acids | unbranched carbon chains that make up most lipids |
phospholipids | have two, rather than three, fatty acids attached to a molecule of glycerol |
triglycerides | a lipid made of three fatty acid molecules and on glycerol molecule |
wax | type of structural lipid consisting of a long fatty-acid chain joined to a long alcohol chain |
steroid | composed of four fused carbon rings with various functional groups attached to them |
nucleic acids | very large and complex molecules that store ad transfer important information in the cell |