CsCl gradients separate on the basis of density, so a molecule made up of ribonucleotides has a slightly, but significantly, blank makes a ribonucleotide molecule slightly heavier than a deoxyribonucleotide molecule, while the volumes occupied are blank. \rm CsCl gradients separate on the basis of density, so a molecule made up of ribonucleotides has a slightly, but significantly, blank density than a molecule made up of deoxyribonucleotides. density than a molecule made up of deoxyribonucleotides.