Which property of molecules in electrophoresis aids in their separation?

The property of molecules that aids in their separation during electrophoresis is their net charge. In an electric field, molecules will migrate towards the electrode with the opposite charge. For example, negatively charged molecules will move towards the positive electrode (anode), while positively charged molecules will migrate towards the negative electrode (cathode). This movement is influenced by the net charge relative to the pH of the buffer used during electrophoresis.

The separation of molecules based on their net charge allows for distinguishing among different types of molecules, such as proteins, nucleic acids, or other charged biomolecules. This characteristic is crucial in various applications, including the analysis of protein isoforms, DNA fragments, and other charged compounds.

Other properties listed, such as solubility in water, can affect how a sample behaves in the electrophoresis medium, but they do not directly influence the separation mechanism itself. Color is not a determinant in the separation process, and while molecular weight can play a role in how far a molecule travels through the gel, it is the charge that primarily drives their migration patterns under an electric field. Thus, the net charge is the key property utilized during electrophoresis for effective separation of biomolecules.