Using M&M's to Model Sanger's Dideoxy DNA Sequencing Method

Abstract

This lesson is designed to facilitate student understanding of the molecular structure of DNA, the cellular processes involved in DNA replication, and how these principles were applied to develop a method to determine the nucleotide sequence of DNA. The lesson employs an active and cooperative learning approach accomplished via a modified jigsaw exercise. The specific replication/sequencing process in this lesson is Sanger's dideoxy method of DNA sequencing. In conjunction with related lessons in lecture and lab, students read the relevant section of an appropriate introductory biology textbook and/or view videos explaining how Sanger's dideoxy chain-termination sequencing method works. Students working in four teams (A, C, G, and T) then use green, blue, brown, and red M&M's as nucleotides to build a model of the process. Plain M&M's represent deoxynucleotide triphosphates (dNTPs), while peanut M&M's represent the “terminator” dideoxynucleotide triphosphates (ddNTPs). The lesson addresses Next Generation Science Standards and learning goals typically found in college biology courses at introductory and advanced levels.