DNA Extraction

Grade Level: Grade 12 Biology; molecular genetics component

Date for Project: Mid-May 2007

Overview: It is possible to extract DNA from a wide variety of living materials using a basic protocol that utilizes everyday materials. While the resulting extract is not as pure as can be achieved in a biotechnology laboratory using more sophisticated techniques and equipment, the process of extracting the dna is one that students find fascinating and it usually produces reasonable results. I propose to have students in my class investigate the protocol(s) for the procedure, practice the techniques, and develop skills to present a videoconference laboratory session to students in another school in our jurisdiction. Our students would present the information to the other class and guide them through their own DNA extraction procedures by demonstrating, explaining the rationale for the various steps in the protocol, answering questions, and giving whatever feedback and guidance would be required by students attempting the procedure for the first time. The receiving class could be either at the same grade level or at a younger grade level, since awareness of DNA technology is part of both junior and senior high school curricula.

Learning Objectives

1. Students will learn the curricular components relating to dna structure and biology. This will include independent research, using the Internet for the most up-do-date material.
2. Students will be introduced to technology associated with dna studies.
3. Students will apply basic lab. safety rules.
4. Students will practice speaking and presenting skills: presenting factual material in a concise and logical way; presenting the steps in a procedure in a clear, easy-to-follow manner.

Preparing the Presenting Class

1. Students will have background information concerning the structure of cells, chromosomes, and dna. This is covered in the course curriculum.
2. Students research dna extraction techniques, learning the purpose of each step of the process: lysing cells, separating proteins and cellular debris from dna, precipitating dna.
3. Students will practice the techniques, learning to identify the dna component and determining the best way of maximizing the dna obtained.
4. Students will also practice explaining the process and the rationale for the various steps.
5. Some students will be assigned the task of preparing a short Powerpoint presentation on the structure of dna, its location in the cell, and its association with proteins in chromosomes.
6. Students will practice with the computers, videoconferencing equipment, and other equipment (document camera) available for their presentation.

Preparing the Receiving Class

1. Discussions and arrangements will be made with the teacher at this site well in advance.
2. Students should have been introduced to cells, chromosomes, and DNA.
3. They will be sent a list of materials and supplies, equipment and copies of the protocol needed to complete the dna extraction. Any safety considerations will be included in this material. This should be sent by e-mail about one week before the actual presentation.

General Plan for 1 hr. class:

1. Time for meeting: introductions of teachers and students from both schools. (10 min.)
2. Powerpoint presentation: nature and structure of dna. (10 min)
3. Guided practice: students from our school will review safety concerns and guide the other class in assembling equipment and proceeding through the steps of the dna extraction. To do this we have the basic vc equipment, but also a document camera that can project 3-D items at both locations. A close-up view may be necessary when it comes time to identify dna vs. proteins and cell debris. (25 min.)
4. Time for comparisons, questions, discussion. (10-15 min.)
5. Wrap-up.

Contingency Plans:

1. Telephone and e-mail contact will be available should the videoconferencing equipment develop problems.
2. The extraction protocol and other information will be in the hands of the receiving school. With a teacher on site, they can proceed on their own by following the steps outlined. Questions and problems could then be dealt with by e-mail.

This project was written by Laraine Hess in the class Planning Interactive Curriculum Connections.