Mouse Genetics One Trait Student Exploration: Mouse Genetics (One Trait) Already Passed

Student Exploration: Mouse Genetics (One Trait) Vocabulary: allele, DNA, dominant allele, gene, genotype, heredity, heterozygous, homozygous, hybrid, inheritance, phenotype, Punnett square, recessive allele, trait Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. The image shows a single litter of kittens. How are they similar to one another? Blue eyes, white sections, facial structure 2. How do they differ from one another? They all have different fur patterns and colors 3. What do you think their parents looked like? It is hard to decide because they all show such different colors and patterns, but one could be orange black and white, and the other could have a brown striping pattern Gizmo Warm-up Heredity is the passage of genetic information from parents to offspring. The rules of inheritance were discovered in the 19th century by Gregor Mendel. With the Mouse Genetics (One Trait) Gizmo™, you will study how one trait, or feature, is inherited. 1. Drag two black mice into the Parent 1 and Parent 2 boxes. Click Breed to view the five offspring of these parents. What do the offspring look like? black The appearance of each mouse is also called its phenotype. 2. Click Clear, and drag two white mice into the parent boxes. Click Breed several times. What is the phenotype of the offspring now? white 3. Do you think mouse offspring will always look like their parents? no Explain: sometimes the parent may carry a trait but not show it and they will pass it down, or there could be a mutation Question: What patterns are shown by offspring traits? 1. Predict: What do you think the offspring of a black mouse and a white mouse will look like? Either gray or spotted 2. Observe: Click Breed several times. What do you see? They are black 3. Observe: Drag two offspring into the Holding Cages. These mice are called hybrids because their parents had different traits. Click Clear, and then breed the two hybrids. What do you see now? Most are black but some are white 4. Experiment: Turn on Show statistics. Click Breed until there are 100 offspring. How many offspring were black? 73 How many were white? 27 5. Explore: Try other combinations of mouse parents. Write the results of each experiment in your notes. When you have finished, answer the following questions. (Note: You can refer to the parents as “pure black,” “pure white,” or “hybrid.”) A. Which parent combination(s) yield only white offspring? Two white B. Which parent combination(s) yield only black offspring? Two black, black and white C. Which parent combination(s) yield a mixture of black and white offspring? Two hybrids 6. Challenge: Based on experiments similar to these, Gregor Mendel devised a theory of inheritance. Use your own observations to come up with your own explanation of how a trait such as fur color is passed down from parents to offspring. Write your explanation down on an extra sheet of paper and attach it to this worksheet. If possible, discuss your theory with your classmates and teacher. Get the Gizmo ready: • Click Clear. • Drag a black mouse and a white mouse into the parent boxes. Get the Gizmo ready: • Click Clear. • Drag a black mouse and a white mouse into the parent boxes, but don’t click Breed yet. Activity A: Patterns of inheritance Activity B: Genetics basics s Get the Gizmo ready: • Click Clear. • Drag a black mouse and a white mouse into the parent boxes. Activity C: Modeling inheritance Introduction: Inherited traits are encoded on a molecule called DNA (deoxyribonucleic acid). Genes are segments of DNA that control a particular trait. Most genes have several different versions, or alleles. The genotype is the allele combination an organism has. Question: How do alleles determine fur color? 1. Observe: Turn on Show genotype. Move your cursor over a mouse to see its genotype. A. What is the genotype of the black parent? FF White parent? ff These mice are homozygous for fur color, meaning both alleles are the same. B. Click Breed. What is the genotype of the offspring mice? Ff These mice are heterozygous for fur color, meaning the alleles are different. 2. Analyze: Dominant alleles are always expressed when present. Recessive alleles are not expressed when the dominant allele is also present. Look at the two alleles for fur color. A. Which allele is dominant, and which fur color does it produce? FF and Black B. Which allele is recessive,