Electrical Pull: The DNA Electrophoresis Principle

If the sugar-phosphate backbone of DNA contains phosphate groups (PO4^3-), then those groups provide a constant negative charge to the entire molecule.

If DNA is negatively charged, and if opposite charges attract, then the DNA must move toward the positive electrode (anode), not the negative one.

If each nucleotide in the DNA strand contains a phosphate group in its backbone, then the cumulative effect of these groups creates a net negative charge.

If laboratory equipment follows standard electrical color coding, and if red signifies the positive terminal, then the DNA will move toward the red side of the tank.

If voltage represents the electrical "push" or pressure, and if that push is increased, then the force acting on the negative DNA will increase, causing it to travel faster.

If an electric current creates a field with a positive pole at one end, and if the DNA is negative, then the DNA will experience an electrostatic pull toward that positive pole.

If pure water is a poor conductor and cannot stabilize pH, then a solution with dissolved ions must be used. If this solution allows current to flow, then it is a buffer.

If an electric circuit is required to move the DNA, then a power source and two electrodes are needed. If the current must travel through the liquid, then a buffer is also required; a vacuum is unnecessary.

If all DNA has the same amount of charge per unit of mass, then the electricity pulls them with equal force. If the gel acts as a mesh, then larger pieces will face more friction and slow down more than small pieces.

If "electro" refers to electricity and "phoresis" comes from the Greek word for "carrying" or "bearing," then the name perfectly describes the dna electrophoresis principle.

If the positive electrode is the anode (red), then the starting electrode where the negative charge originates is the negative cathode.

If the speed depends on the "push" and the "resistance," then voltage and gel density are key. if the size of the DNA determines how much it bumps into the gel, it also affects velocity.

If the cathode is the negative electrode and the DNA is also negative, then like charges will push away from each other. If this repulsion occurs, it helps drive the DNA toward the positive end.

If the separation requires an active "driving force" to pull the DNA through the gel mesh, then without current, the DNA will only diffuse slowly and randomly. If it doesn't move in one direction, then it won't separate.

If the voltage is spread across the length of the gel, then there is a steady drop in potential from one side to the other. If this drop exists, then it is the electrical gradient that pulls the DNA.

If the system uses charge to create movement, then attraction and repulsion are the forces. If the DNA starts moving, then the energy has been converted to kinetic (movement) energy.

If an electric current faces resistance in the buffer and gel, then that resistance generates heat. If too much heat (thermal energy) accumulates, then the agarose gel will lose its solid structure.

If DNA is negative and is placed next to the positive electrode, then it will immediately move toward that electrode. If the wells are at the positive end, then the DNA will move "backward" out of the gel.

If pure water does not have enough free-moving charges to complete a circuit, then it acts as an insulator. If salt is added, then the ions carry the charge from one electrode to the other.

If the DNA needs to travel across the length of the gel to be separated, and if it moves toward the positive end, then it must start at the furthest point away, which is the negative end.