AP BIOLOGY

Detailed explanation-1: -DNA samples are placed in a special gel and subjected to an electric field. Because DNA is negatively-charged, it moves toward the positive electrode. The DNA fragments that are shortest will travel farthest, while the longest fragments will remain closest to the origin.

Detailed explanation-2: -Smaller molecules migrate through the gel more quickly and therefore travel further than larger fragments that migrate more slowly and therefore will travel a shorter distance.

Detailed explanation-3: -Because all DNA fragments have the same amount of charge per mass, small fragments move through the gel faster than large ones.

Detailed explanation-4: -The smallest fragments travel the most distance. DNA is a negatively charged molecule and it will migrate to the positively charged electrode when an electric current is supplied to the gel. The shorter strands of DNA move faster across the gel than longer strands, the fragments are organized in size order.

Detailed explanation-5: -The smaller DNA fragments travel faster and farther because they move more easily through the gel. To better understand this concept, imagine that a small DNA fragment is a small metal object, a large DNA fragment is a large metal object, and the positively-charged end of the gel is a magnet.