Welcome to my unit on DNA structure and function, which address (MS-LS3 Heredity: Inheritance and Variation of Traits) from NGSS. The purpose of this unit is for my students to understand how the structure of DNA facilitates the mechanism behind genetic flow of information. My unit begins with exploring structure of DNA (i.e. nucleotide structure) and subsequently with DNA transcription and DNA translation to eventual protein.
In this particular lesson, students are to develop and use a paper model to describe how structural changes to genes (mutations) may affect proteins and may result in harmful, beneficial, or neutral affects to the structure and function of an organism.(Performance Expectation MS-LS3-1).
As a science teacher, I always strive to connect the science content to my students' everyday lives. In middle school, the life science curriculum becomes more abstract, addressing concepts that students may have little foundational knowledge to build upon. I engage students by validating my students' interests, especially their interest in popular media and technology.
During this warm-up I show a series of movie clips from the movie Spiderman - the scene showing Peter Parker being bitten by a spider resulting in a mutation of his DNA, and a follow up scene where Peter Parker has been ultimately transformed into Spiderman.
I follow up video with the following questions:
1) Please describe what you saw in the clip, include words such as DNA, double helix, and bases.
2) Predict if Peter Parker will change after this incident, if so will this change be beneficial or damaging?
After watching the third clip, I ask the following question.
3) Based on the evidenced gathered does a change in DNA sequence affect the characteristics (i.e. physical traits) of living things? Please support claim with evidence gathered from the video (CCSS - SL 8.5).
In this part of my lesson I have students take Cornell Notes from the Mutations PowerPoint. This presentation introduces students to the concept of mutations including the different types (i.e. mismatch, deletion, insertion) and eventual expression in an organism of these differing types.
Students are expected to use the Cornell Note-taking System, and are introduced to it 6th grade. It is a particularly effective tool for science because it organizes thinking, and supports the use of visuals (drawings).
In this part of the lesson students explore the three types of mutations (mismatch, deletion, insertion) by using a paper strip model. (SP2 - Developing and Using Models). The paper strip model represents the folding patterns of proteins.
The following is the-step-by step procedure for this activity.
A. Correct Sequence
B. Mis-match sequence
C. Deletion Sequence
D. Addition sequence
2) Next, students cut and fold each strip following the bold lines to create a folded protein structure. Each student folds 4 distinct protein structures A, B, C, D.
3) To identify a DNA sequence as regular or as one of the mutation types (mismatch, deletion, or insertion) students place a folded protein structure into a Mutations Triangle. Only A) will fit in a Mutations Triangle. B, C, D will not fit due to irregular folds that ultimately create an irregular protein structure. This part of the lesson addresses the following Crosscutting Concepts 1) Cause and Effect - (A major activity of science is investigating and explaining causal relationships and the mechanisms by which they are mediated) and Structure and Function (The way in which an object or living thing is shaped and its substructure determine many of its properties and functions.). This activity allows students to see that as a result of a DNA mutation, a proteins structure and hence its function will be affected.
4) Students identify strips B, C, D by counting number of folds (i.e. strip C represents gene deletion mutation due to 1 less fold, strip D represents gene addition mutation due to 1 additional fold, and strip B represents mismatch gene mutation due to change in direction of 5th fold).
I have attached two additional resources 1) Mutation Permutations, which introduces three types of mutations along with directions for the activity, and 2) Mutation Guided Notes, which can be used to assess students understanding of three types of mutations.
The DNA Mutations Exit Slip assesses students understanding of both content (MS-LS3-1) and crosscutting concepts. In addition is requires students to write by using claim and evidence (W.7.1/SP7 - Engaging in Argument form Evidence). A critical element of developing a deep and lasting understanding is having students grapple to find the words that express their understanding. Writing also is a reflective activity through which students can discover (and so do you) their gaps in understanding.