Model Organisms (Lesson)

Students work through a series of experiments that investigate the use of model organisms in the search for a better understanding of the genes that influence memory formation.

G2C Online Title of Activity: Go to the Head of the Class! Lesson Overview Students work through a series of experiments that investigate the use of model organisms in the search for a better understanding of the genes that influence human learning and long-term memory formation. The fruit fly (Drosophila) is the featured organism. Initially the experiments using the Fly School simulation are guided. Students are asked to interpret the results of these experiments and how studies of Drosophila apply to human learning. Students are next asked to design a series experiments. They are free to select from four [NOTE: We should put more genes in here] fruit fly variants and compare learning in one of these to learning in wild type flies. The last part of the activity brings students to the Model Center where they compare the proportion of protein that is the same for the creb and rut genes in a number of model organisms. They are asked to decide which species should be selected for the next round of research and to support their decision. Goals and Objectives Students will: 1. formulate hypothesis 2. design a controlled experiment 3. analyze and interpret the results of a series of experiments 4. recognize the value of model organisms in scientific research 5. understand that the molecules of learning and memory have been conserved by evolution 6. apply the findings of experiments with model organisms to human learning Assumptions of Prior Knowledge Students should have some knowledge of experimental design. They should also have a basic understanding of DNA, transcription, translation, and protein formation. Some knowledge of model organisms would be helpful. Common Misconceptions Students do not clearly understand that specific proteins in humans are the same or very similar to those in other species. This is especially true when comparing humans and fruit flies or chickens. Students often think that each species has its own unique set proteins. Students think that cramming the night before an exam is adequate and that they will retain the information for the long run. A misconception of convenience is that frequent review of the material provides no more benefit than cramming. The Lesson Preparation Before class: (materials, handouts etc.) Photocopy the Go to the Head of the Class student sheets. You can elect to have students work alone or in pairs. During class: Before starting the lesson, ask students how they prepare for a test. Ask them if cramming the night before an exam works as well as reviewing several times over a period of days? Then ask those who play sports, does running a new play many times one day work as well as running the new play several times over many days? How does their coach deal with this? Explain that in both cases, they are learning something new and that the goal is to commit the information to long-term memory so that it is there when they need it…on an exam or during an athletic competition Discuss with them that scientists are using model organisms to investigate what factors influence human learning and long-term memory formation. Next, give students the activity and have them go to Provide students with information about how to navigate the site and how to find Fly School. Time required This activity requires one 90-minute block or two 45-minute periods. (This is nothing more than a guess!) The actual lesson plan including assessment I’m not sure what you want here. Mary, this is where the text, Go to the Head of the Class, should go Suggestions for Extended Learning (I’ll add this later. Perhaps you will have some suggestions. I want to see more of the web site first.) We can work on this. Glossary (terminology)- Gene Hypothesis Model organism T-maze Resources (for ex.) (later) Web Video/DVD Books Articles National Science Education Standards Science as Inquiry Abilities necessary to do scientific inquiry Understandings about scientific inquiry • Scientists conduct investigations for a wide variety of reasons. For example, they may wish to discover new aspects of the natural world, explain recently observed phenomena, or test the conclusions of prior investigations or the predictions of current theories. • Scientists rely on technology to enhance the gathering and manipulation of data. New techniques and tools provide new evidence to guide inquiry and new methods to gather data, thereby contributing to the advance of science. The accuracy and precision of the data, and therefore the quality of the exploration, depends on the technology used Life Science The Cell • Most cell functions involve chemical reactions. • Cells store and use information to guide their functions. The genetic information stored in DNA is used to direct the synthesis of the thousands of proteins that each cell requires. • Cell functions are regulated. Regulation occurs both through changes in the activity of the functions performed by proteins and through the selective expression of individual genes. This regulation allows cells to respond to their environment and to control and coordinate cell growth and division. The Behavior of Organisms • Multicellular animals have nervous systems that generate behavior. Nervous systems are formed from specialized cells that conduct signals rapidly through the long cell extensions that make up nerves. The nerve cells communicate with each other by secreting specific excitatory and inhibitory molecules. In sense organs, specialized cells detect light, sound, and specific chemicals and enable animals to monitor what is going on in the world around them. • Organisms have behavioral responses to internal changes and to external stimuli. Responses to external stimuli can result from interactions with the organism's own species and others, as well as environmental changes; these responses either can be innate or learned. The broad patterns of behavior exhibited by animals have evolved to ensure reproductive success. Animals often live in unpredictable environments, and so their behavior must be flexible enough to deal with uncertainty and change. Plants also respond to stimuli. • Like other aspects of an organism's biology, behaviors have evolved through natural selection. Behaviors often have an adaptive logic when viewed in terms of evolutionary principles. • Behavioral biology has implications for humans, as it provides links to psychology, sociology, and anthropology. Science and Technology Understandings About Nature and Technology • Creativity, imagination, and a good knowledge base are all required in the work of science and engineering. • Science and technology are pursued for different purposes. Scientific inquiry is driven by the desire to understand the natural world, and technological design is driven by the need to meet human needs and solve human problems. Technology, by its nature, has a more direct effect on society than science because its purpose is to solve human problems, help humans adapt, and fulfill human aspirations. Technological solutions may create new problems. Science, by its nature, answers questions that may or may not directly influence humans. Sometimes scientific advances challenge people's beliefs and practical explanations concerning various aspects of the world. History and Nature of Science Science as a Human Endeavor • Individuals and teams have contributed and will continue to contribute to the scientific enterprise. • Scientists have ethical traditions. Scientists value peer review, truthful reporting about the methods and outcomes of investigations, and making public the results of work. Violations of such norms do occur, but scientists responsible for such violations are censured by their peers. Nature of Scientific Knowledge • Science distinguishes itself from other ways of knowing and from other bodies of knowledge through the use of empirical standards, logical arguments, and skepticism, as scientists strive for the best possible explanations about the natural world. • Scientific explanations must meet certain criteria. First and foremost, they must be consistent with experimental and observational evidence about nature, and must make accurate predictions, when appropriate, about systems being studied. They should also be logical, respect the rules of evidence, be open to criticism, report methods and procedures, and make knowledge public. Explanations on how the natural world changes based on myths, personal beliefs, religious values, mystical inspiration, superstition, or authority may be personally useful and socially relevant, but they are not scientific. • Because all scientific ideas depend on experimental and observational confirmation, all scientific knowledge is, in principle, subject to change as new evidence becomes available. Note: Fly image from Answer Key A. Use the information provided to explain why your first round of experiments should be done with wild type flies and not one of the other variants. These flies are the typical form found in nature and are often used as controls to measure normal responses. B. Now the moment of truth! Did you train your flies? Do they remember which odor is associated with the electrical shock? Were you successful? Explain. Yes. The flies were trained. They knew which way to go. Background Model organisms can be used to test hypotheses. With model organisms, answers to scientific questions can usually be obtained faster and without many of the ethical dilemmas caused by using human subjects. For example, we can knock-out specific genes and study what the subsequent changes in behavior or physiology. Discoveries made using model organisms provide insight into the workings of other organisms – including humans. This activity examines learning and memory in the fruit fly, Drosophila melanogaster. Fruit flies, are easily bred, reach maturity in a matter of days, and share many genes with humans. As a result of their popularity as a model organism, much is known about their genes and the role of the environment in the expression of these genes. The genes responsible for learning and memory in humans are modeled in the fruit fly. You will explore a number of genes that can dramatically effect memory – one of which can induce a type of photographic memory. Investigations of these genes in model organisms such as the fruit fly could potentially lead to treatments for disorders such as Alzheimer’s. However, manipulating these genes also assumes important ethical responsibilities. * Go to G2C Online ( > Will add later > Fly School and read the introduction. The Investigation Fruit flies are sensitive to a wide variety of odors. It is your task to work through a series of experiments that determine under what conditions fruit flies learn to avoid a specific odor. Once they have learned which odor to avoid, you also want them to remember it for as long as possible. A training chamber designed as a simple t-maze will allow your flies to choose to move to the right or the left. You will manipulate a number of variables such as with which odor to administer an electric shock, whether to provide your flies with one training session or ten, and more. Lets get started! To learn more about flies and learning, read the information on the first slide of Fly School. Then click the Start button

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  • ID: 1361
  • Source: DNALC.G2C

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