Chicken Genetics Gizmo Answer Key

Name: Shannon Calderon Date: 02-21-2022 Student Exploration: Chicken Genetics Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes. Vocabulary: allele, codominance, dominant, genotype, heterozygous, homozygous, phenotype, probability, Punnett square, recessive, trial Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. The image shows a flower that was produced by crossing a pure red flower with a pure white flower. Which do you think is the dominant petal color: red or white? Explain. The heterozygous flower exhibits both the red and the white alleles, indicating that they are most likely codominant. 2. How is the inheritance pattern shown by this flower different from other inheritance patterns you have seen or studied? One allele is typically dominant and will always be visible above the other in a complete dominance situation. When there is codominance, a heterozygous person will have both features since both alleles are equally dominant. Gizmo Warm-up There are many different ways traits can be inherited. Some traits are governed by alleles that are dominant over other alleles. Other traits are governed by alleles that share dominance. These alleles follow a pattern of inheritance called codominance. With the Chicken Genetics Gizmo, you will study how codominance affects the inheritance of certain traits. 1. Turn on Show genotype. The genotype is the allele combination an organism has. Point to the red chicken. A. What is the red chicken’s genotype? B. What is the white chicken’s genotype? 2. What do you think the letters F, R, and W stand for in the genotypes? The letter F stands for the color of a chicken's feathers, while the letters R and W indicate the color of red and white, respectively. Activity A: Codominant traits Get the Gizmo ready: ● Drag a red chicken and a white chicken into the parent boxes, but don’t click Breed yet. Question: What inheritance patterns do codominant traits display? 1. Predict: What do you think the offspring of a red chicken and a white chicken will look like? They will all acquire one codominant red feather allele and one codominant white feather allele, resulting in a mixture of red and white feathers. 2. Observe: Click Breed. What are the offspring genotypes? An organism’s appearance is its phenotype. Describe the offspring’s phenotype. Red and white feathers are blended on all of them. 3. Experiment: Drag four offspring to the Holding Cages. Click Clear, and then drag one of the offspring to a parent box. Drag a white chicken to the other box. Click Breed several times. Describe the resulting genotypes and phenotypes of the offspring. Both white-feathered produced as progeny. chickens and red-and-white-feathered chickens were 4. Revise and Repeat: Click Clear. Drag another chicken from the Holding Cages to the parent box. Drag a red chicken to the other box. Click Breed several times. Describe the resulting genotypes and phenotypes of the offspring. Both red-feathered the offspring. chickens and red-and-white-feathered chickens were among 5. Explain: In dominant/recessive inheritance patterns, the dominant allele is always expressed when present. The recessive allele is only expressed when the dominant allele is not present. Use your observations from this activity to describe how codominant inheritance patterns differ from dominant/recessive inheritance patterns. In codominance inheritance patterns, both alleles are equally dominant whereas only one allele is dominant in dominant/recessive inheritance patterns. Although genetic inheritance functions essentially the same for both types, a heterozygous creature will look different for each type. In codominance patterns, the phenotype would appear to be an equal mixture of the two traits, whereas in dominant/recessive patterns, heterozygous genotypes would have a phenotype that reflects the dominant trait. Activity B: Codominant crosses Get the Gizmo ready: ● Click Clear. ● Drag the remaining chickens from the Holding Cages into the parent boxes. Introduction: Probability is the likelihood that a specific event will occur. Scientists use probability to predict the outcomes of different genetic crosses. Question: How can you use probability to predict the outcome of a codominant cross? 1. Model: A Punnett square is used to model the possible offspring genotypes from a genetic cross. The parent genotypes are written at the top and side of the square, as shown. The possible offspring genotypes are then filled in. The first square is filled in for you. Fill in the remaining squares. (Note FRFW is equivalent to FWFR.) FR FR FW FR FR FR FW FR FW FW FW W F 2. Analyze: A homozygous chicken will have the same alleles for feather color. A heterozygous chicken will have two different alleles for feather color. A. Are the parents homozygous or heterozygous? Explain how you know. Due to their genotypes having one codominant redfeather allele and one codominant white feather allele, the parents are both heterozygous. B. What are the possible genotypes of the offspring? C. Will the offspring be homozygous or heterozygous? The progeny may be homozygous or heterozygous. 3. Calculate: Punnett squares can be used to predict probable outcomes of genetic crosses. To calculate probability, divide the number of one kind of possible outcome by the total number of all possible outcomes. For example, if you toss a coin, the chance it will land on heads is equal to 1 ÷ 2. This probability can be expressed as ½, 0.5, or 50%. Look at the Punnett square above. A. How many total possible outcomes are there? 4 B. How many of the possible outcomes are there for each of the following genotypes? FR FR 1 FW FW 1 FR FW 2 C. What is the probability for each of the following outcomes? (Record answers as both fractions and percentages.) FR FR ¼=25% FW FW ¼=25% FR FW 2/4=50% 4. Test: Use the Gizmo to test your predicted outcomes. Turn on Show statistics and Show as approximate percentage. Click Breed. What are the results of the cross? 80% red/white feathers, 20% white feathers, and 0% red feathers were the outcomes. 5. Evaluate: Did the results of the cross match your prediction? If not, why do you think that was the case? With the exception of the fact that the red/white birds produced the majority of the offspring, these results did not correspond to the theoretical values. Because just one study was undertaken, the results were not particularly accurate. The sample space will grow as more trials are run, increasing the theoretical accuracy of the results. 6. Collect data: Click Breed 19 more times until you have generated 100 offspring. How do the percentages match your prediction now? Have they gotten to be more or less similar to your original prediction? Now, 27% of the feathers are red, 17% are white, and 56% are a combination of red and white. Even if the findings are still slightly off, they are much closer to the expected values presently. 7. Compare: Click Breed until you have generated at least 1,000 offspring. Compare the statistics on the Gizmo with your original predictions. How close are they? In the end, there were 49% red/white feathers, 26% white feathers, and 26% red feathers. Each of these predictions is barely 1% off from what I had projected, which is incredibly close. 8. Draw conclusions: Each time you bred the parent chickens, you completed a trial. A trial is a single time that you conduct an experiment. Random chance often causes identical trials to have different outcomes. Because of this, scientists repeat experiments many times in order to make sure that chance alone is not responsible for the results of a trial. How did your results change as the number of trials you completed increased? Why was it important for you to breed the chickens repeatedly in this experiment? As more trials were completed, the more theoretically accurate the results became. Due to the factthat there are more outcomes, the variation of the results is less subject by chance and begins toreflect the broader patterns of allele inheritance more accurately. This is why it is important to complete as many trials as possible for an event before making conclusions; it will help to maintainaccuracy in the data and attain the best results possible.