QUESTIONS FOR ALL GROUP MEMBERS: TAKE NOTES ON A SEPARATE PIECE OF PAPER!

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1 Exceptions to Mendel Honors Each group will have 4 members. Each member must become an expert for a group of exceptions, they will then be responsible for teaching the rest of the group and helping them solve related questions (not answering the questions for them). QUESTIONS FOR ALL GROUP MEMBERS: TAKE NOTES ON A SEPARATE PIECE OF PAPER! INCOMPLETE DOMINANCE AND CODOMINANCE p166 and 167 (person responsible for teaching: ) 1. What is incomplete dominance? 3. Why didn t Mendel s pea plant experiments demonstrate incomplete dominance? 4. Solve the incomplete dominance problem designed by the group member responsible for teaching 5. What is codominance? 6. Why is this an exception to Mendel s research? 7. Why didn t Mendel s pea plant experiments demonstrate codominance? 8. Solve the codominance problem designed by the group member responsible for teaching MULTIPLE ALLELES p167 (person responsible for teaching: ) 1. Explain multiple alleles. 3. Why didn t Mendel s pea plant experiments demonstrate multiple alleles? 4. What are the human blood type phenotypes and genotypes? 5. Solve the multiple allele problem designed by the group member responsible for teaching POLYGENIC TRAITS p169 (person responsible for teaching: ) 1. What are polygenic traits? 3. Why didn t Mendel s pea plant experiments demonstrate polygenic traits? 4. Solve the polygenic trait problem designed by the group member responsible for teaching 5. What is an example of a polygenic trait in humans. 6. Define pleiotropy (p169), how is this different from polygenic? SEX LINKAGE p (person responsible for teaching: ) 1. What is sex linkage? 3. Why didn t Mendel s pea plant experiments demonstrate sex linkage? 4. How would you write the genotype for a male with colorblindness phenotype? How would you write the genotype of his normal vision mother? 5. Solve the sex linkage problem designed by the group member responsible for teaching this exception.

2 INCOMPLETE DOMINANCE AND CODOMINANCE p166 and 167 job to teach your group about incomplete and codominant. 1. What is incomplete dominance? 3. Solve the following incomplete dominance problems: 1. In humans straight hair (HH) and curly hair (hh) are incompletely dominant traits, that result in hybrids who have wavy hair (Hh). Cross a curly hair female with a wavy haired male. 2. In radishes, the gene that controls color exhibits incomplete dominance. Pure-breeding red radishes crossed with pure-breeding white radishes make purple radishes. What are the genotypic and phenotypic ratios when you cross a purple radish with a white radish? 4. Develop your own incomplete dominance problem (you can use something from the text, the examples above or come up with your own example). Make a key for the problem. 5. How many different phenotypes can exist in a population of organisms for a trait that is incompletely dominant? 6. What is codominance? 7. Why is this an exception to Mendel s research? 8. Solve the following codominance problems: 1. A very common phenotype used in questions about codominance is roan fur in cattle. Cattle can be red (RR = all red hairs), white (WW = all white hairs), or roan (RW = red & white hairs together). A good example of codominance. a. Predict the phenotypic ratios of offspring when a homozygous white cow is crossed with a roan bull. b. What should the genotypes & phenotypes for parent cattle be if a farmer wanted only cattle with red fur? 9. Develop your own codominance problem (you can use something from the text, the 10. How many different phenotypes can exist in a population of organisms for a trait that is codominant?

3 MULTIPLE ALLELES p167 job to teach your group about multiple alleles. 1. Explain multiple alleles. 3. Create a table showing phenotypes and genotypes for the ABO blood groups in humans. 4. Solve the following multiple allele problems: 1. A woman with Type O blood and a man who is Type AB have are expecting a child. What are the possible blood types of the kid? 2. What are the possible blood types of a child who's parents are both heterozygous for "B" blood type? 3. In mice, the skin or coat color is governed by a multiple allelic series. The gene A controlling the agouti pattern in mice has several alleles. Among the members of the series a gradation exists in dominance, similar to that of the c series in rabbits, but in this case two members, Ay (yellow) and A1 (agouti light belly) are dominant over the wild-type allele A+ (agouti). The alleles of agouti (A) series in mice can be listed according to dominance in table. Phenotype Allele Yellow A Y Agouti light belly A l Agouti A + Black and tan a l Nonagouti (Black) a Dominance hierarchy: A Y >A l >A + >a l >a In this multiple allelic series, the allele Ay, when homozygous, (i.e., A Y A Y ) is lethal early in embryonic development. a. What would the phenotype be for a mouse with the genotype A + a? b. Cross a homozygous Black and tan mouse with a Agouti light belly mouse with the genotype A l a, what ratios would you expect in the offspring of this mating? c. Cross two yellow mice both with the genotypes A Y a l, what ratios would you expect in the offspring of this mating? 5. Develop your own multiple allele problem (you can use something from the text, the 6. How many different phenotypes can exist in a population of organisms for a trait that is controlled by multiple alleles?

4 POLYGENIC TRAITS p169 job to teach your group about polygenic traits. 1. What are polygenic traits? 3. Solve the following polygenic problems: Note: the polygenic model makes the following 6 simplifying assumptions: Each contributing gene has small and relatively equal effects.the effects of each allele are additive. Their is no dominance, instead the genes behave as if they follow incomplete dominance. The value of the trait depends solely on genetics; environmental influences can be ignored. 1. Kernal color in wheat is determined by two gene pairs, so called polygenes that produce a range of colors from white to dark red depending on the combinations of alleles. Dark red plants are homozygous AABB and white plants are homozygous aabb. When these homozygotes are crossed the F1 offspring are all double heterozygotes AaBb. Thus crossing individuals with the phenotype extremes yield offspring that are a 'blend' of the two parents. This illustrates an important point that many times when you have two parents who differ in phenotype for some characteristic, there is a tendency for the offspring to be intermediate to the parents in phenotype. This phenomenon is sometimes called regression to the mean. a. Predict what will happen when the two double heterozygotes are crossed? b. Predict the outcome when a heterozygous plant is crossed with a white plant 4. What is an example of a polygenic trait in humans. 5. Develop your own polygenic problem (you can use something from the text, the examples above or come up with your own example). Make an answer key for the problem. 6. How many different phenotypes can exist in a population of organisms for a trait that is controlled by polygenic traits? 7. Define pleiotropy (p169), how is this different from polygenic?

5 SEX LINKAGE P job to teach your group about sex linked traits. 1. What is sex linkage? 3. How would you write the genotype for a male with colorblindness phenotype? How would you write the genotype of his normal vision mother? (use notation from figure 9.23B-D) 4. Solve the following sex-linked trait problems: 1. For any given couple what is the likelihood of having a boy? Make a punnent square for this problem. 2. In humans the gene from normal blood clotting, H, is dominate to the gene for hemophilia, h. This is a sex-linked trait found on the X chromosome. A woman with normal blood clotting has four children. They are a normal son, a hemophiliac son, and two normal daughters. The father has normal blood clotting. What is the probable genotype for each member of the family? 3. A certain form of muscular dystrophy is inherited as a sex-linked, recessive gene. Jack has muscular dystrophy. (Neither of his parents has this disease.) Jane, Jack s wife, does not have muscular dystrophy, but her father does. What fraction of their daughters would you expect to have muscular dystrophy? What fraction of their sons would you expect to have muscular dystrophy? 5. Develop your own sex-linked trait problem (you can use something from the text, the