DNA molecules of different sizes are often separated with the use of a technique called electrophoresis (see Chapter 19). With this technique, DNA molecules are placed in a gel, an electrical current is applied to the gel, and the DNA molecules migrate toward the positive (+) pole of the current. What aspect of its structure causes a DNA molecule to migrate toward the positive pole?

Explanation:

A DNA molecule is a polymer of nucleotides, which are made up of a nitrogenous base, a sugar and a phosphate group.

The phosphate groups are negatively charged, giving the sugar-phosphate backbone a negative charge. This negative charge causes the DNA molecule to be attracted to the positive pole of the current and thus migrate towards it.

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: