List the four macromolecules that make up cells and give a brief description of the structure and ...

Carbohydrates include small, water-soluble sugars and large polymers made of sugars. In the cell, carbohydrates have three important functions: They are structural components of cells; they act as energy sources for the cell; and, in combination with proteins on the surface, they give cells a molecular identity.

Lipids are a structurally and functionally diverse class of biological molecules partially defined by their insolubility in water. Lipids have many functions: They are structural components of membranes, some serve as energy reserves, while others act as hormones and vitamins. Lipids are classified into three major groups: fats and oils, phospholipids, and steroids. The phospholipids play important roles in the structure and function of the cell membrane.

Proteins are the most functionally diverse class of macromolecules. Proteins are polymers, made up of one or more chains of subunits, called amino acids. The varied structures of proteins are reflected in their diversity of functions.

Nucleic acids are polymers made from nucleotide subunits. Nucleotides themselves have important functions in energy transfer, but nucleic acids are the storehouses of genetic information in the cell. The information is encoded in the nucleotide sequence.