We can say that the top of the gel, where the DNA samples were applied, is the negative side, while the bottom of the gel is the positive side.
We can arrive at this answer because:
- DNA is a negatively charged molecule.
- For this reason, when DNA is applied in an electrophoresis vat, it must be placed in the negatively charged portion.
- This is because the electrophoresis vat will allow an electrical discharge to pass through the vat and drag the DNA from the negative side to the positive side.
This movement allows the DNA to present a series of fragments of different sizes that will be observed in a fingerprint, such as the one presented in the question above.
In the figure below you can more accurately see the positive and negative sides.
More information:
https://brainly.com/question/14440067?referrer=searchResults
