Chapter 13, Problem 20STP

Summary Introduction

To describe:

The error occurred and electrophoresis and the way to adjust the experimental procedures to test the explanations.

Introduction:

The technique of separating DNA fragments based on their size is termed as gel electrophoresis. In this technique, DNA samples are added to well at the end of the gel. Then, electric current is applied through the gel. As DNA is negatively charged, DNA fragments go towards the positive electrode.

Explanation of Solution

In the given gel electrophoresis experiment, some DNA fragments’ bands were missing from the gel and some DNA fragments were found at the far end of the gel. The mistake here done in the experiment is with concentration of DNA samples. Some samples are too concentrated, that they moved too slowly across the gel and some samples were too less concentrated that they moved very fast at the end of the gel. Moreover, if the gel electrophoresis is run for a long period, then also DNA sample can leak out from the gel. This mistake can be adjusted by making accurate concentrations of DNA samples and running gel for only required period of time.