In this activity, students extract DNA from their cheek cells and relate the steps in the procedure to the characteristics of cells and biological molecules. Students learn key concepts about the function of DNA during the intervals required for the extraction procedure. A second optional section develops student understanding of the fundamentals of DNA structure, function and replication; this section includes hands-on modeling of DNA replication.

Download Student Handout: PDF format or Word format

Download Teacher Preparation Notes: PDF format or Word format

The Teacher Preparation Notes provide instructional suggestions and background information and explain how this activity is aligned with the Next Generation Science Standards.

We invite comments on this Hands-On Activity and the accompanying Teacher Preparation Notes, including suggestions for other teachers who are planning to use the activity, useful preparatory or follow-up activities, additional resources or any questions you have related to the activity, or a brief description of any problem you might have encountered. If you would prefer to send your comments or questions in a private message, please write Ingrid Waldron at iwaldron@sas.upenn.edu.

See also a complete list of activities:
Hands-on Activities for Teaching Biology to High School and Middle School Students



iwaldron's picture

2014 revisions

The Student Handout has substantially revised questions to improve student learning of the most important concepts related to the structure, function and replication of DNA. In addition, the revised Student Handout incorporates hands-on modeling of DNA replication. The Teacher Preparation Notes have been revised to accommodate these changes, to indicate alignment with the Next Generation Science Standards, and to suggest follow-up activities. 

Serendip Visitor's picture

DNA extraction

I completed this lab, but modified the protocol so that students sampled DNA from cheek cells, wheat germ and various types of fruit ( we used bananas and strawberries). Students worked in group of 3 or 4, and each student was assigned a different source for DNA. The students then compared their results.

iwaldron's picture

Extracting DNA from Different Sources

This is an interesting approach. I am curious what the students found when they compared the DNA extracted from different sources. How did you interpret what they observed?

iwaldron's picture

October 2011 revision

The revisions of the Student Handout have clarified and improved the questions for students to answer as they learn about DNA structure and replication, and also incorporated improved figures.  The revised Teacher Preparation Notes have incorporated suggestions for extracting DNA from split peas (as an alternative to extracting DNA from cheek cells), clarified the teaching points, and added suggestions for linking this activity on DNA structure and replication to learning activities concerning DNA function.

Zaynab's picture

Suppose that DNA did not have

Suppose that DNA did not have a double helix structure, and instead DNA was single-stranded. Imagine that a cell with this single-stranded DNA was ready to begin cell division. How could a cell replicate single-stranded DNA so the daughter cells could receive an exact copy of the genes present in the original cell? Use your answer to explain why it is an advantage for DNA to have a double helix structure with paired nucleotides.

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