Final answer:
Agarose in gel electrophoresis is used for making the gel, which serves as a matrix to separate DNA fragments based on their size, with smaller fragments moving faster and farther through the gel than larger ones.
Step-by-step explanation:
In gel electrophoresis, agarose is used for making the gel. Agarose is a polymer made from seaweed and is the medium through which the DNA samples are separated by size when an electric current is applied through the gel. The DNA fragments are loaded into wells in the agarose gel and move towards the positive electrode due to their negative charge.
The smaller DNA fragments move faster and farther through the gel compared to larger ones due to the molecular sieving effect of the agarose matrix. The gel does not act as a dye, mixer for the samples, or a marker for DNA; rather, it is a matrix that facilitates the separation of DNA molecules based on their size. Following separation, the DNA is visualized using a DNA-specific dye, not the agarose.