A single strand of DNA contains:

A single strand of DNA is a polymer of nucleic acids joined covalently between the phosphate group of one and the deoxyribose sugar of the next to for a “backbone” from which the nitrogenous bases stick out. In its natural state, DNA has two strands wound around each other in a double helix.

Explanation:

the form of energy changes and the total energy increases0l

the dna molecules have a negative charge because of the phosphate groups in their sugar-phosphate backbone, so they start moving through the matrix of the gel towards the positive pole. power is turned on and dna fragments migrate through gel (towards the positive electrode).

explanation: