Given that the dna molecules all have similar charge to mass ratios, what property do you think is most important in determining migration in the gel?

The answer is size. The larger the DNA molecule the slower it travels through the gel.  This is because of the restriction of their movement through the pores of the gel. The smaller DNA molecules travel furthest. The size of the pores can be varied through by changing the mixture ratios of the agarose gel.

However, particles will move in straight lines until they collide with something. Collisions usually change the speed and direction of the particles movements. If the motion of particles slows the particles move closer together. This is because the attraction between them pulls them toward each other.

Explanation:

Larger particles move slower, due to their larger mass and may be influenced by numerous collisions with many nearby smaller particles. Smaller particles move faster. ... Hotter particles move faster because they have more energy. The rate of diffusion increases as temperature increases because the particles move faster. You're welcome :) - xoxo madster