Conversations of Genetics: Two Stories of Huntington's Disease

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Objective

Students will apply concepts of statistics and probability to two case studies to construct an explanation for the genetic basis of Huntington's Disease.

Big Idea

Understanding the impact of Huntington's disease involves a delicate balance of conversations with counselors and genetic calculations!

Introduction

Lesson Background & Justification:

        Huntington's Disease is an autosomal dominant inherited disease that causes the progressive breakdown (degeneration) of nerve cells in the brain, particularly in the Basal Ganglia of the brain which is responsible for involuntary functions of the body. Huntington's disease has a broad impact on a person's functional abilities and usually results in movement, thinking (cognitive) and psychiatric disorders that progresses with nerve degeneration. This lesson, (the first half of a 2 part lesson) specifically sets the stage for students to comprehend both the behavioral and genetic criteria for Huntington's Disease. Command of this content in this first lesson later serves as a primer for students to digest more complex tasks related to the disease such as a detailed molecular analysis and bioinformatic applications.  The second day of the lesson can be found here.

Essential Prior Knowledge: Prior to experiencing this lesson, students should be familiar with the following content/concepts:

             a) Structure and Function of DNA  

             b) Gene Expression and Protein Synthesis  

Lesson Preparations:

 In the effort to prepare for this lesson, I make certain that I have the following items in place: 

a) A class set of the lesson Science Take Out: Genetic Testing for Huntington's Disease. (1 per student pair). Note: This lesson as a stand alone is recommended to be completed within 4-5, 40 minutes class sessions. This lesson, however will utilized segments of the lesson to build a set of experiences for students that will be accommodated within 2, 90 minute blocks.

b) A class set of Huntington's Disease Case Study (1 per student)

c) Student lab books.

Common Core and NGSS Standards:

SP2- Developing and Using Models.

HS-LS3-1-Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring. 

HS-LS3-3-Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population.

MS-LS3-2-Develop and use a model to describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation.

RST.11-12.2- Determine the central ideas or conclusions of a text; summarize complex concepts, processes, or information presented in a text by paraphrasing them in simpler but still accurate terms.

MP1- Make sense of problems and persevere in solving them. 

MP4- Model with mathematics.

Standards Rationale: 

       In the science classroom, students are regularly charged with tasks to collect and make sense of data from readings and investigations. What makes these science experiences powerful enough to retain however, is an instructor's ability to access, stimulate and develop students' higher order thinking capacities for cognitive growth and subsequently establishing sound learning practices. In this lesson, students access, analyze & interpret scientific data using mathematical modeling and analyze case studies to deductively refine a physical and genetic criteria for Huntington's Disease. They utilize higher level Blooms thinking skills such as problem solving and modeling exercises which in tandem serve to intimately connect students to the tangibles and intangibles throughout the lesson. This promotes higher engagement and time on task as students absorb the content at hand.  

Engage

30 minutes

Section Primer:

     A  Neurodegenerative Disease is an umbrella term for a range of conditions which primarily affect the neurons in the human brain.  Diseases and/or conditions classified under this term are characteristically incurable and debilitating and result in progressive degeneration and / or death of nerve cells. This causes problems with movement (called ataxias), or mental functioning (called dementias). In this section of the lesson, students interface and attempt to reconcile the experiences of two young women within two different case studies in order to define and grasp the magnitude of one neurodegenerative disease: Huntington's Disease.   

Section Sequence:

a) Ask: "Are you aware of genetic diseases in your family or in a family that you befriend?" Continue to direct the classroom conversation so that it encourages students to divulge names of some the diseases (if they are comfortable with sharing) and to share emotions the families experience while coping with the diseases. Transition by sharing that the lesson of the day taps into this problem and how different families deal with similar genetic issues. 

b) Slide 1: Share with students that we will start with a case study of young lady concerned about her uncle and that the condition of concern will be elucidated by the class using clues from parts of the case study. Distribute the first page of the Huntington's Disease Case Study (all terms that identify the condition should be whited out including Parkinson's and Alzheimers and the disease referred during the reading as Disease X). As the class reads the passage aloud, instruct students to highlight key pieces of information regarding the disease and share these items with the teacher to list these in the symptom/problems box on the projected slide (as  an alternative record the contents of slide 1 on the dry erase board to fill in). Next, direct students to examine the fully generated list on the board and to infer which parts of the brain and parts of the neuron are potentially impacted based on the unknown condition's symptoms. Illustrate and/or label student suggestions using the diagrams provided. Instruct students to plug the symptoms list into their own technology devices (BYOT) to search for and generate a list of probable conditions that fit their criteria.  Finally, instruct students to share their findings and record their disease/condition suggestions on the board under the "Possible Conditions" heading.  

c) To narrow the name of the condition even further, bring students attention to the proposed list of conditions presented on the board from slide 1 and then share with them that there is more to Amanda uncle's story. Avail the specific cognitive, physical and emotional problems (Slide 2) and share that these symptoms had also been "observed" in him. Instruct students to use these extensive lists of problems to refine/narrow their search for a condition that satisfies his criteria. Record the top 2-3 proposed conditions under the heading "Final Diagnosis" and circle the condition Huntington's Disease on the board to inform students that this is the condition that he is suffering from and share that affects cells in the basal ganglia of the brain. Finally, walk the class back through the case study information and fill in all of the blanks together as a class.  

d) Slide 3: Share with students that they are now going to read up on concerns from another young lady from a different family who has a loved one with this condition as well. Distribute the Genetic Testing for Huntington's Disease lab package materials and proceed to direct students through the specifics outlined on the slide. 

Standards Covered:

HS-LS3-1-Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring. 

RST.11-12.2- Determine the central ideas or conclusions of a text; summarize complex concepts, processes, or information presented in a text by paraphrasing them in simpler but still accurate terms.

MP1- Make sense of problems and persevere in solving them. 

Explore

45 minutes

Section Primer: 

                 In biology, a pedigree is a diagram showing genetic relationships between members of a family. It is used to analyze patterns of inheritance for specific genetic traits. In this section of the lesson, the goal is to provide students with a hands on model that will gradually and progressively introduce students to the relationship between sexual reproduction and inheritance probability via standard punnett square and pedigree analysis. The goal is to provide students with a stimulating, gateway manipulative that has the potential to develop students in traditionally intimidating skill of biology: Mathematical Analysis.

Section Sequence:      

a) Slide 4: Share with students that they will now explore the genetic side of Huntington's disease. Specifically, share that they will examine how the genes that the families of two young ladies possess travel through generations and impact one's susceptibility to the condition. Tell students to be mindful of how the condition's genetics may potentially impact the two young ladies from our case studies and to consider how they may frame this factor into a conversation between the young ladies in their comic strips. 

b) Instruct students to complete Step 1 (part 2 of the Science Take Out lab package/materials, pages 8-11) presented on the slide with their partners and give them 30 minutes to execute the task. 

c) Share with students that they will now analyze the same genetics pattern of Huntington's Disease, but this time they will visualize it through a Pedigree chart. Access and project the following virtual pedigree activity: Human Pedigree Analysis by clicking on the play button icon at the bottom left part of the screen and guide the class through the slides. Read and conduct the activities as prescribed by each frame in the activity. Allow for a few students to read the introduction and you as the instructor read the text beneath practice problems. Allow students ample time to analyze each pedigree, vote (by a majority show of hands) on a response and justify their final responses with verbalized justifications for the selected responses to assess if they have accurately deciphered how the pedigree works. 

d) Share with students that they will now use the pedigree analysis tool to predict the genotypes of a family with HD in their gene pipeline.  Access and project the following virtual activity: Inheritance of Huntington's Disease by clicking on the play button icon at the bottom right part of the screen. Display the family figures only (no alleles) and prompt students to recall the inheritance pattern of Huntington's from the lab. Ask: "Based on each person's phenotype, what do you think the genotypes of each person is in this pedigree?" Instruct students to work the problem out in their lab book before proceeding to share out. Finally, encourage students to share out with justifications after unveiling each genotype one by one. 

e) Additional Practice (Slides 5 and 6): Advance and facilitate each prescribed task as outlined on the slides. These are opportunities for students to gain more practice with predicting the probability of inheriting HD before they develop another conversation frame between the characters in their comic strips. Some students struggle with understanding genetics and therefore require adequate practice before confidently assessing the cases at hand. This will in the end help them to record more scientifically accurate information. 

Standards Covered: 

SP2- Developing and Using Models.

HS-LS3-1-Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring. 

HS-LS3-3-Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population.

MS-LS3-2-Develop and use a model to describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation.

RST.11-12.2- Determine the central ideas or conclusions of a text; summarize complex concepts, processes, or information presented in a text by paraphrasing them in simpler but still accurate terms.

MP1- Make sense of problems and persevere in solving them. 

MP4- Model with mathematics.

Wrap up!

15 minutes

Section Sequence:

     In this section of the lesson, my objective is to give students an opportunity to distill all of the content accumulated throughout the lesson. Specifically, students will use comic strip development to summarize the relationship between the genetic pattern of Huntington's Disease and the implications for them as a family member in the affected pedigree. 

Slide 7: Read and facilitate students through the wrap up activity as listed on the slide. Collect and grade based on accuracy of probable predictions described in the dialogue bubbles for each person. 

Standards Covered:

HS-LS3-1-Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring. 

HS-LS3-3-Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population.

MS-LS3-2-Develop and use a model to describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation.

RST.11-12.2- Determine the central ideas or conclusions of a text; summarize complex concepts, processes, or information presented in a text by paraphrasing them in simpler but still accurate terms.

MP1- Make sense of problems and persevere in solving them.