Now, linear simply means we have a beginning and we have an end. And this is in contrast to circular nucleic acids that don't have a beginning and don't have an end. The polymer means we have these individual subunits that link together to make up the nucleic acid. And in nucleic acids, these monomers these subunits are known as nucleotides. Now, every one of these nucleotides consists of three different groups. We have a sugar molecule, we have a phosphate group and we have a nitrogenous base.