Chapter 5
The Molecules of Life
Vocabulary
Organic molecules: carbon based molecules that help make up living organisms.
Inorganic molecules: non-carbon based molecules such as water, oxygen, and ammonia. Makes
up nonliving matter.
Monomer: small molecular unit that is the building block of a larger molecule.
Polymer: a long chain of small molecular units (monomers).
Hydrophilic: water loving – attracted to water molecules.
Hydrophopbic: water fearing – repels water.
Dehydration reaction: reaction where a water molecule is released every time a monomer is
added to a polymer chain.
Hydrolysis reaction: reaction where water is added to break apart a polymer chain.
Carbohydrate: an organic compound made up of sugar molecules. Contains the elements
carbon, hydrogen and oxygen in a 1:2:1 ratio. Molecular structure has a ring shape.
Monosaccharide: simple sugars that contain only one sugar unit. Ex: glucose, galactose, &
fructose
Disaccharide: a double sugar formed by 2 monosaccharides. Ex: sucrose.
Polysaccarharide: long polymer chains of simple sugar monomers. Ex: starch, glycogen,
cellulose.
Fats/Lipids: store energy in the body. Consists of a 3-carbon backbone called a glycerol
attached to 3 fatty acids. Ex: steroids & fats.
Saturated fat: a fat in which all 3 fatty acid chains contain the maximum possible number of
hydrogen atoms. Ex: animal fats, lard and butter.
Unsaturated fat: a fat in which one or more of the fatty acid chains contain less than the
maximum possible number of hydrogen atoms. Ex: corn oil, olive oil, fruits and vegetables, and
fish.
Protein: a polymer constructed from a set of 20 different kinds of amino acids. Responsible for
the everyday functioning of organisms. Fnc: making, hair, muscle and long term nutrient storage.
Amino acid: monomer of a protein. 20 different ones
(8 essential & 12 nonessential) – essential you must get from the food you eat.
Activation energy: the minimum amount of energy needed for a chemical reaction to proceed.
Enzyme:special proteins that control the rate of a reaction. They act as catalysts which speed up
the rate of a reaction by lowering the activation energy needed.
Substrate: a specific reactant acted upon by an enzyme. The enzyme “fits” into the substrate
which attached at the active site to speed up the rate of a reaction.
Active site:place where the enzyme attached to the substrate forming the enzyme-substrate
complex..
Catalyst:an enzyme that speeds up the rate of a chemical reaction by lowering the activation
energy.
Exothermic reaction:a chemical reaction that releases energy called free energy that can be
used for other work.
Endothermic reaction:a chemical reaction that requires the input of energy for the reaction to
occur.