Gel Electrophoresis using Food Dyes

Dye Electrophoresis Lab Introduction
In this lesson, students will explore the process of agarose gel electrophoresis to figure out which food dye molecules give Skittles candy their colors. This lab is helpful to complete before other labs involving gel electrophoresis including DNA Forensics and PCR labs
Read More

    Initially, students will predict the direction of the dye migration based on their understanding of how size and charge govern the movement of molecules. Students then extract food dye from Skittles®, load these samples into an agarose gel using a micropipette, and run a current through the gel to separate the dye molecules. They will be able to predict, observe, and compare the movement of their extracts with known food dyes.

    To conclude, students will make a claim about what food dye(s) is/are present in their Skittle® and support it using evidence from their gel and reasoning about the scientific principles behind electrophoresis.

Lesson Resources
Student Guide – Download and edit student worksheets to be completed during the Dye Electrophoresis Lab.
Lesson Slides – Articulates with the student guide above and accompanying lesson plans below.
Lesson Plan – Suggested times for pacing, sequence and activities for the lab. Includes vocabulary tool, supplemental resources, etc.

Lab Resources
Student Lab Protocol – Students follow these instructions when doing the Dye Electrophoresis Lab.
Preparing the Classroom for the Lab – How to set up group stations for this lab experience.
Inventory Guide – Reagents and materials checklist for one classroom kit. Includes equipment and classroom needs for the lab.

– Accurately and precisely measure small
Perform agarose gel electrophoresis to
separate food dye molecules based on
charge and size
– Predict the behavior of a molecule on an
agarose gel based on its size and charge
– Make a claim about which dyes are used to
make Skittles and support it using
evidence and reasoning.

Disciplinary Core Ideas:
– PS1.A Structure and Properties of Matter
“…interactions of matter at the bulk scale are determined by electrical forces within and between atoms.”
– PS2.B Types of Interactions
“Attraction and repulsion between electric charges at the atomic scale explain the structure, properties, and transformations of matter…”

Science and Engineering Practices:
– Engaging in Argument from Evidence
Students make a claim about what food dye(s) is/are present in their Skittle and support it using evidence from their gel and reasoning about the scientific principles behind electrophoresis.

Crosscutting Concepts:
– Structure and Function
Students explore the relationship between a molecule’s structure and its behavior in gel electrophoresis.

Familiarity with the following concepts may be helpful for students prior to using the lesson resources.
– Relationship between atoms and molecules
Difference between positively and
negatively charged molecules
– Using micropipettes to measure and
transfer small volumes
Kitty MeiGel Electrophoresis using Food Dyes