DNA Fingerprinting Lesson Plan

Transcription

1 EDUC 4510A: Biology Curriculum and Methodology A Assignment 2 DNA Fingerprinting Lesson Plan Ellen Gillett a

2 DNA FINGERPRINTING TEACHER NOTES Prerequisite Knowledge Prior to this lesson, students will have learnt about the polymerase chain reaction (PCR) and the structure and properties of DNA. SACE STAGE 2 Lesson Title: SCSI: School Crime Science Investigation Lesson Length: 100 mins Objectives Following this lesson, students will be able to: Describe gel electrophoresis and some of its applications in the wider community Understand the process of DNA Fingerprinting Materials Projector/Smartboard Whiteboard, whiteboard markers and eraser Tape to outline body for crime scene Classroom pictures (objects and room views) Suspect pictures Gel Electrophoresis/DNA Fingerprinting PowerPoint

3 DNA FINGERPRINTING LESSON PLAN PRIOR TO CLASS: Set up room to look like a makeshift crime scene make the outline of a body on the floor in tape, take a series of photos of the classroom and possible items of interest and stick these together on one wall, make five wanted posters of possible suspects and stick these together on another wall. Introduction and Warm-up (Visual) 5 min The lesson involves students (the police) and the teacher (the chief of police) attempting to piece clues together to solve the crime and arrest the suspect (one of the five wanted people). Begin the lesson by telling the class about the crime (eg: murder) and that their role is to determine the person responsible. Point out the crime scene, photographic evidence and suspects around the room. Note that the crime scene was clean with only a small amount of blood collected by forensics, and no trace of fingerprints. Handout (Linguistic/Intrapersonal) 5 min Distribute a bulletin with information about the crime, victim and suspects. Allow students to read through the sheet individually. Crime Scene Investigation (Visual/Interpersonal/Kinaesthetic) Allow the students to wander around the room/crime scene, taking notes and observations as they progress. Encourage group work and collaboration. Guiding questions: - Is there any evidence we can use? - How might we determine who was responsible with only one small vial of blood?

4 Crime Scene Discussion (Kinaesthetic/Visual) Ask students to return to their seats. Initiate a class discussion about how they could solve the crime. Scaffold the discussion so that students realise PCR can be used to amplify DNA in the blood. Then ask students if they know how to determine the murderer from the amplified DNA (lead to the introduction of Gel Electrophoresis). Gel Electrophoresis (Linguistic/Visual) Using Gel Electrophoresis PowerPoint, explain that amplified DNA from PCR reactions can be visualised via Gel Electrophoresis. Explain that Gel Electrophoresis is achieved using by running a current through a matrix/gel. Stress that DNA is negatively charged, and moves through the gel from negative to positive. Larger DNA fragments take a longer time to move through the matrix (they become caught up in the matrix), while shorter fragments move quicker. Show an example picture of a gel and briefly describe how to interpret the picture. Ask students if they have any questions. Ask students how Gel Electrophoresis could be used to help solve the crime. Scaffold the experimental approach so students are aware that DNA from blood should be extracted, amplified using PCR, then used in Gel Electrophoresis. PRACTICAL: Blood DNA Extraction (Kinaesthetic/Visual) 40 min Explain to students that they will perform DNA extractions on blood samples (NOTE: blood samples are squished strawberries) and send them to the police laboratories for PCR and Gel Electrophoresis. Give students the protocol (Strawberry DNA Extraction Protocol) and select a few students to read it aloud. Ensure the class understands the protocol and necessary safety precautions before commencing. Once students are finished collect the tubes and ask students to clean their bench space before returning to their seats.

5 Gel Electrophoresis Analysis (Visual/Interpersonal/Mathematical) Following DNA Extraction, explain to students that the results from the police laboratories have been fast tracked, and the Gel Electrophoresis pictures are already available. Distribute the Gel Electrophoresis results (see below for an example image). Ask students to work in groups of two or three to identify the murderer. Ask for a show of hands to determine which of the five suspects is believed to be the murderer and ask one or two students to explain why they believe they are the murderer in relation to the Gel Electrophoresis results. Congratulate class on solving the crime! Summary (Linguistic) Summarise key points of the lesson: - Even small amount of DNA (in a tube of blood) can be analysed following PCR Gel Electrophoresis summary (watch Gel Electrophoresis video) Agarose gel is a matrix and a current is run through this gel DNA fragments (negatively charged) move through the matrix from negative end to positive end Larger DNA fragments take a longer time to move through the matrix, while shorter fragments move quicker - DNA Fingerprinting can be used in crime scene investigations and paternity testing (can students think of any other applications?) Ask students about the ethical, economic and cultural issues associated with DNA fingerprinting and the collection of DNA/genetic material to discuss in the next lesson.