Electrophoresis and Gel Quantitation

Advanced Preparation


This laboratory will enable students to develop an important laboratory skill. Gel quantitation is important for scientists working with DNA on a daily basis. If a restriction digest was carried out on a cosmid or other large piece of DNA and a particular sized fragment was desired, not only the size would be important, but the quantity of DNA in the fragment would also be important to estimate. A technician would know if they needed to cut more DNA in order to account for the loss of DNA in the gel purification protocol. This technique provides an estimation of the amount of DNA in a particular fragment. A more accurate method is to quantitate with a spectrophotometer over a range of wavelengths.

Student Objectives

Class time needed

One class period to complete initial estimations, one class period to do extensions.


  1. Pictures for students to use: at least one per student
  2. Rulers
  3. Calculators

Recipes for Making gels

0.8% agar is made by adding 0.8 grams of agarose and 99.2 grams of 1X TBE buffer. Microwave on medium for l-2 minutes. DO NOT CLOSE. PUT PAPER TOWEL OVER TOP OR INTO TOP OF CONTAINER.