Glucose is considered to be a monomer. It is made of a chain of 6 carbon atoms linked by single covalent bonds. Five Hydroxyl (OH) groups and seven hydrogen atoms are also linked to the carbons. Two different stereoisomers of glucose exist in nature.
Proteins are made of amino acids linked by peptide bonds. This means that carbon, oxygen, nitrogen and hydrogen are the main atoms present. The polypeptide chain formed by the initial linking of amino acids often undergoes several folding steps and may have other atoms or molecules, known as prosthetic groups, added to it before it becomes a complete and functional protein. Iron, in the form of a heme group, is an example of a prosthetic group found in hemoglobin.
Lipids are made primarily of fatty acid molecules, which consist of a hydrocarbon chain with a carboxylic acid group at one end. Functional groups including oxygen, nitrogen, sulfur, or members of the Halogen family are commonly found attached to the hydrocarbon chain as well. The main physical feature that distinguishes fats from oils in this group is saturation, which in this case refers to the structure of the carbon-carbon bonds in the hydrocarbon chain. A saturated fat is generally a solid fat, and has all single carbon-carbon bonds. Unsaturated fats have some double or triple bonds between carbons, and are generally oils at room temperature.