* Proteins: Proteins are made up of long chains of amino acids (the monomers). These chains fold into complex 3D structures, giving proteins their diverse functions.

* DNA: DNA is made up of long chains of nucleotides (the monomers). Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base. The sequence of these bases forms the genetic code.

Let's look at the other options:

* Salts: Salts are ionic compounds formed by the electrostatic attraction between positively charged ions (cations) and negatively charged ions (anions). They are not made up of long chains of monomers.

* Ethanol: Ethanol is a simple organic molecule with a single carbon chain. It's not a polymer.

* Carbohydrates: Carbohydrates can be made up of long chains of sugars (monosaccharides), but they are not always long chains. Simple sugars like glucose are single monomers. Starch and cellulose are examples of carbohydrates with long chains of monomers.

In summary: Only proteins and DNA are always made up of many monomers joined together in long chains.