Chapter 3- The Molecules of Cells

organic compounds

compounds that are synthesized by cells and contain carbon


things made of hydrogen and carbons

carbon skeleton

the chain of carbon atoms in organic molecules;
can be unbranched (butane) or branched (isobutane)


compounds with the same molecular formula but different structures

functional groups

the groups in an organic molecule that usually participate in chemical reactions


water loving; soluble in water

hydroxyl group

a group that consists of a hydrogen atom bonded to an oxygen atom. the O is bonded to the carbon skeleton of a molecule

carbonyl group

a group where a carbon atom is linked by a double bond to an oxygen atom; if the carbon atom in the group is at the end of the carbon skeleton, it is called an aldehyde. If the group within a carbon chain is called ketones

carboxyl group

a group where an oxygen atom double- bonds to a carbon that is also bonded to a hydroxyl group.

carboxylic acids

an acid that contains carboxyl groups

amino group

a group composed a nitrogen atom bonded to 2 hydrogen atoms.


organic compounds with an amino group


a gigantic molecule that makes up life; includes 4 classes


a large molecule consisting of many identical or similar molecular units strung together.


units that are the building blocks of polymers

dehydration synthesis

the process where cells link together to form polymers; for each monomer added to chain, a water molecule is removed.


a process where cell bonds break bonds between monomers by adding water to them.


a class of macromolecules which include mono- and polysaccharides;


a monomer for carbohydrates; generally have the molecular formula of CH2O; includes glucose and fructose


a double sugar made from 2 monosaccharides through dehydration synthesis; includes sucrose


polymers linked together through dehydration synthesis; includes starch and sugar


a storage polysaccharide in plant roots; made up of glucose monomers; the helix can be branched or unbranched


a polysaccaride used by animals to store excess sugar


a polysaccharide made of glucose monomers and used as walls in plant cells


a class of macromolecules that consist of carbon and hydrogen atoms linked by nonpolar covalent bonds


water fearing; don't mix with water


a large lipid made from glycerol and fatty acids


another name for fat; made of glycerol and 3 fatty acids


fatty acids and fats with double bonds; they have less than the max. number of hydrogen


fats with the maximum number of hydrogens


a component of cell membranes; are similar to fats, but contain phosphorus


consist of a fatty acid linked to an alcohol; are hydrophobic, so are used as natural water-proof coating for animals


A type of lipid characterized by a carbon skeleton consisting of four rings with various functional groups attached.

anabolic steroids

a synthetic variant of the male hormone testosterone that mimics some of its effects


a polymer made from amino acid monomers; there are 7 classes


protein that acts as a biological catalyst; can speed up chemical reactions

amino acid

organic compounds containing an amino group and a carboxylic acid group

peptide bond

the bond between 2 amino acids in a polypeptide; made by dehydration synthesis


a chain of amino acids linked by peptide bonds


a process in which a protein unravels and loses its native conformation, thereby becoming biologically inactive. For DNA, the separation of the two strands of the double helix; occurs under extreme conditions of pH, salt concentration, and temperature.

primary structure

The first level of protein structure; the specific sequence of amino acids making up a polypeptide chain.

secondary structure

The second level of protein structure; the regular local patterns of coils or folds of a polypeptide chain.

alpha helix

A spiral shape constituting one form of the secondary structure of proteins, arising from a specific hydrogen-bonding structure.

pleated sheet

One form of the secondary structure of proteins in which the polypeptide chain folds back and forth, or where two regions of the chain lie parallel to each other and are held together by hydrogen bonds.

tertiary structure

The third level of protein structure; the overall, three-dimensional shape of a polypeptide due to interactions of the R groups of the amino acids making up the chain.

quaternary structure

The fourth level of protein structure; the shape resulting from the association of two or more polypeptide subunits.

nucleic acids

polymers that serve as blueprints for proteins


a type of nucleic acid that holds genetic information


a type of nucleic acid that translates genetic information given by DNA


chemical factors that determine traits


monomers that make up nucleic acids

phosphate group

a functional group consisting of a phosphorus atom covalently bonded to four oxygen atoms

nitrogenous bases

the nitrogen containing bases of the nucleotide

double helix

two strands of nucleotides wound about each other; structure of DNA