Question

How do you interpret gel electrophoresis results?

Answer 1

Hint: Agarose gel electrophoresis refers to a molecular biology technique. It is used for the separation of DNA fragments on the basis of their size and to analyze the separated fragments of the DNA.

Complete answer:
Agarose gel has a mesh-like structure which facilitates the separation of DNA fragments. Smaller DNA fragments shows a rapid movement through these pores while larger fragments get stuck in these pores and hence they show retarded movement.
The gel is allowed to settle with hollow pockets (called the wells) present at one end of the gel surface. The DNA is thus loaded in these wells. DNA has negative charge due to the presence of phosphate backbone. This allows DNA molecules to migrate towards the anode which is positively charged. The distance travelled by the DNA molecules in an agarose gel is proportionate to its logarithmic molecular weight.
-For comparing the bands obtained by given samples, the samples in the agarose gel are put next to each other.
-Generally, the supercoiled form shows rapid movement than the other forms of DNA molecules due to their compact structure. Therefore, they are found down in the gel.
-However, the linear monomers as well as open circular monomers move slowly as compared to the supercoiled monomers. It is more challenging for them to pass through the pores of the gel than the supercoiled forms. Hence the open circular monomers are found up in the gel.

Note: The migration of the plasmid DNA is affected by the conditions of the gel electrophoresis which includes ionic strength of the electrophoretic buffer, temperature, electric field strength, gel concentrations and the presence of ethidium bromide. The plasmid DNA which is circular in shape is easily captured in the agarose mesh.