Discovering Dna 721j5d

Structure of DNA Lesson Plan Instructor: Wendi Straub Introduction: Students are somewhat familiar with the term DNA, as it was likely studied in junior high school life science and is commonly used in all sorts of common media (TV shows, news, movies, books, etc.). However, most students (and most people, in general) do not really understand what DNA is, how DNA directs cells and organisms or how it can be ed from parent to offspring. The answer to how DNA functions and how it can be reliably copied over and over lies in its simple, yet elegant structure. In this lesson, students develop the intimate knowledge of DNA’s chemical structure necessary to comprehend how genetic information is coded, copied and transcribed. This lesson is intended to follow the historical experiments that established DNA as the primary source of heritable genetic material and the contributions from Chargaff, Watson, Crick, Wilkins, and Franklin to reveal DNA’s structure. In prior lessons, basic chemistry including biological macromolecules, cell structure and cell division have been covered. Content Area and Grade or Age Level of Students: High School General Biology Objectives: At the conclusion of this lesson students will be able to  Identify DNA’s location in a eukaryotic cell  Describe how DNA is packaged to form a chromosome  Explain the relationship between nucleotides and nucleic acids  Explain the relationship between DNA and genes  Draw a simple representation of a single nucleotide that correctly relates the three components: 5-C sugar, phosphate and base  Draw a simple ladder representation of a section of DNA double helix with correct antiparallel complementation and label the sugars, phosphates, bases, covalent bonds, hydrogen bonds  Apply the base pairing rules to correctly determine the sequence of a complementary strand of DNA from a given strand sequence  Apply Chargaff’s ratios to correctly determine the relative percentages of the three remaining nucleotides in a DNA sample from one known percentage  Explain how the two types of chemical bonds (hydrogen and covalent) allow DNA strands to separate without damaging the genetic code  Correctly use the following : nucleotide, nucleic acid, double helix, complementary, antiparallel  Explain that each cell in an organism begins with the same DNA sequences (chromosomes/genome) because they are copies descended from a single original cell. Standards Addressed: Idaho Science Content Standards (2012) (http://www.sde.idaho.gov/site/content_standards/science_standards.htm ).

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9-10.B.1.2.1 Use observations and data as evidence on which to base scientific explanations. (648.02a) 9-10.B.1.2.2 Develop models to explain concepts or systems. (648.02b) 9-10.B.1.6.1 Identify questions and concepts that guide scientific investigations. (649.01a) 9-10.B.3.3.1 Identify the particular structures that underlie the cellular functions. (651.01a) 9-10.B.3.3.3 Explain how cells use DNA to store and use information for cell functions. (651.01c)

Relative Advantage: DNA is too small for students to observe directly and they struggle to visualize the molecular structure and relationships between the components. Representations and analogies are critical for students to understand this molecule, and we construct physical models. However, the physical models are less facile or representative of the actual structure. Virtual models and other animated representations are critical to students developing an accurate concept. Finally, this lesson follows a pseudo-flipped plan in which students complete research first, and then use that information in a class-wide discussion to establish concept parameters, followed by lab to provide a concrete example and another for practical and engaging application. This blended learning model is designed for groups whose access to technology is limited outside of class (as is the case for a significant percentage of our students), but it does provide for learning outside of class for those who need more time or are absent. Timeline: (5 instructional days) Materials: Digital resources  18 Things You Should Know About Genetics video at https://www.youtube.com/watch?v=bVk0twJYL6Y  Breaking the Code video at https://www.youtube.com/watch?v=N7TI0ytVa9I  Access to Building DNA GIZMO http://www.explorelearning.com/index.cfm?method=cResource.dspView&ResourceI D=439  DNA virtual extraction lab at http://learn.genetics.utah.edu/content/labs/extraction/  The twisting tale of DN video at http://ed.ted.com/lessons/the-twisting-tale-of-dnajudith-hauck Internet accessible device – preferably one per student, but could pair students. Course Website – pdf mock up attached at the end (Appendix A) DNA model Lab materials – lab record and paper templates beads and string or pipe cleaners, kinex, edibles and toothpicks, etc.  DNA model examples - http://www.melodyshaw.com/files/dnadone.pdf ; http://www.mysciencebox.org/book/export/html/347; http://biology.about.com/od/biologysciencefair/a/aa102005a.htm  http://www.accessexcellence.org/AE/ATG/data/released/0185-EllenMayo/index.php  I have attached the one I developed a few years ago at the end of the lesson plan. (Appendix B)

DNA Extraction Lab materials – Bio-RAD’s Genes in a Bottle is a complete kit from http://www.bio-rad.com/en-us/product/genes-bottle-kit , but there are many cheaper, DIY labs too. Attached is my lab handout. (Appendix C) Grouping Strategies: Students will be working individually with computers and in teams and pairs to build DNA models. Learning Activities: Day 1 – Engage, establish purpose and begin student research 1. Engage a) Show video: 18 Things You Should Know About Genetics b) Think. Pair. Share: We are living in a fantastic age of biology right now. Since scientists revealed the structure of DNA in 1953, advances in molecular biology have revolutionized how we define life, how we think life is organized, and how living things can be changed, naturally and by man. We are unraveling some of life’s most fundamental mysteries. We now understand lots of these things in ways that were inconceivable 50 years ago. o Think: Each person come up with at least two ways we use our knowledge about DNA today – either positive or negative, then brainstorm two ways you think we might be able to use it in the future. Ideas can be captured in a regular or digital notebook, mini dry erase boards, tablet whiteboard app, etc. o Pair: share your answers with another person in your group o Share: Classroom list and discussion. Be sure to establish the impact of DNA in our society (medicine, agriculture, genealogy, forensics, etc.) This is a great opportunity to reveal misconceptions. A possible extension is to have students research the state of their brainstormed ideas for the future – they may be surprised by how much or how little progress. 2. Establish Purpose a) Play video Breaking the Code b) In this lesson we will study the structure of DNA by looking at those nucleotide building blocks, how nucleotides are built and how they are connected to form a strand of DNA and how two strands form the double helix. You will study and build both virtual and physical models of DNA from just a single sequence of the four letters discussed in the video. Finally, we will extract DNA from our own cells using common chemicals that interact with cellular and DNA structures. 3. Instruction Day 2 – Finish student research a) Have students gather information from the course webpage with tours, presentations, videos and links on DNA structure (a pdf mock up similar to what I have designed for class is attached). Day 3 – Review structure and students practice with GIZMOs b) Review the structure of DNA on the board by having students contribute information they learned from their note taking. This should be an open note exercise. Correct any misconceptions or fill in any gaps

c) Have students practice building a DNA molecule using the GIZMO site with a guided lab. Day 4 – Construct DNA models d) DNA Structure Models (attached) - there are many, many DNA model building labs with paper, kits, candy, beads and more. I adapted a paper model years ago in which students make nucleotides in table groups, then lab pairs are given a 9 letter sequence to build one strand, then use that strand to build the second strand. Each lab pair will use these DNA constructs to model replication and finally, transcription and translation to follow the central dogma from a gene to RNA to protein. Day 5 - Extract DNA e) DNA extraction lab in which students use common household chemicals to extract and visualize their own DNA from a saliva sample. (DNA virtual lab extraction for absent students at http://learn.genetics.utah.edu/content/labs/extraction/ 4. Check for Understanding a) Circulate among students to ask and answer questions b) Provide scaffolding as needed 5. Closure a) Play video The twisting tale of DNA - Judith Hauck to re-establish value of learning about DNA and connect to next topic – DNA replication Assessment: DNA Model and lab are scored with a project rubric at the end of the unit; extraction lab graded in class; and related content will be on end of unit exam and end of course assessment Adaptations for Learners with Special Needs: Multiple modes of delivery – audio, visual, and manipulative plus peer resources mitigate a lot of special needs concerns. ELL students use classroom iPads to translate materials and search for alternative language videos. Both ELL and lower achieving students are grouped to provide additional peer resources in the form of bilingual or caring and capable partners. Assignments with a lot of reading and writing may be shortened and additional scaffolding (such as guided notes, differentiated web resources, lab directions read aloud, additional modeling, attention, etc.) provided by instructor. References: Benedetto, D. and Hoppe, K. (2010). Who's the Daddy? - Science.net. Retrieved July 1, 2014, from http://www.science.net/genpblwhosdaddywhole.pdf. (2011).DNA Worksheet - Lessonplans.Inc. Retrieved July 1, 2014, from http://www.lessonplansinc.com/lessocnplans/dna_ws.pdf Concept 19: The DNA molecule is shaped like a twisted ladder (2011).DNA from the beginning -DNA Learning Center. Retrieved July 1, 2014, from http://www.dnaftb.org/19/.