1. How are traits inherited? How would you design an experiment to determine how a physical characteristic is inherited? Aug 311

2. Gregor Mendel Nature was orderly Quantitative approach Natural laws could be described in mathematical terms Rediscovery of Mendel’s work Chromosome theory of inheritance Mendel’s laws worked in many organisms Mendel’s laws could explain inheritance in humans Aug 312

3. Pisum sativum: the Pea plant, a model organism Variation in physical traits Self and cross pollinate Easily manipulated flowers Large numbers of progeny Aug 313

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6. Mendel’s Results Two discrete hereditary factors, one from each parent The two factors may be identical or different When the two factors of a single trait are different One is dominant and its effect can be seen The other is recessive and is not seen During gamete formation, the paired factors segregate randomly Particulate theory of inheritance Mendel’s Law of Segregation Aug 316

7. Consider a plant in which flower color is controlled by a single gene with 2 alleles. Blue color is dominant to white. Use B for the dominant allele and b for the recessive allele. Give the expected genotypic and phenotypic ratios for the following crosses: BB x bb Bb x bb Bb x Bb Blue X white If you cross a blue x white and see blue and white progeny, what were the genotypes of the parents? Aug 317

8. Where does segregation occur? Aug 318

9. 3.2 In Betta fish, solid color is dominant to Cambodian coloration (c ) (where the body is pale but the fins are dark). You cross a Cambodian fish to a solid fish and 20 offspring are solid and 17 are Cambodian. What are the genotypes of the parents and offspring? You cross two solid fish and 27 of the offspring are solid and 10 are Cambodian. What are the genotypes of the parents and offspring? Aug 319

10. You are studying coat color in tribbles, a sexually reproducing, diploid species of animals from outer space. Tribbles have either brown fur or blonde fur and you have evidence that coat color is determined by a single gene with 2 alleles (B and b). You cross two tribbles (Tarzan and Jane) and they produce two pups (Fred and Alice) Tarzan (blonde male) X Jane (brown female) Fred (brown males) and Alice (brown female) Give a plausible one autosomal gene, two allele model to explain these data: Model 1: Based on model 1, give the color phenotype of each of the following genotypes: BBBbbb What are the genotypes of the tribbles? Tarzan (blonde male)Jane (brown female) Fred (brown male)Alice (brown female) Aug 3110

11. Give a different, plausible one autosomal gene, two allele model to explain the difference. (Your model should change—i.e. which allele is dominant/ recessive, don’t just change the genotypes) Model 2: Based on model 2, give the color phenotype of each of the following genotypes: BBBbbb What are the genotypes of the tribbles? Tarzan (blonde male) Jane (brown female) Fred (brown male)Alice (brown female) Aug 3111

12. You decide to use the rapid reproductive rate of tribbles to distinguish between the two models. You decide to cross two of the tribbles you have multiple times and collect many offspring from these crosses. You design your cross carefully so that the results of the cross will unambiguously allow you to determine which is the correct model (1 or 2). Which two tribbles do you pick (must have 1 male and 1 female)? If model 1 is correct, what will be the results of the cross between the chosen tribbles? Give the expected ratio of coat colors. If model 2 is correct, what will be the results of the cross between the chosen tribbles? Give the expected ratio of coat colors. Aug 3112

13. Multiplication Rule AND To determine the probability that two separate events will happen Multiply the probabilities of each event Addition Rule OR To determine the probability of one of two mutually exclusive events If one occurs the other cannot Add the probabilities of each event Aug 3113

14. Achondroplasia is a form of dwarfism controlled by one gene with two alleles. Two achondroplasitic dwarfs have two children, one a dwarf and one of normal stature. (Please note that I am using dwarf here because the general medical term for being of less than normal stature is dwarfism—most people affected by this disorder or other genetic disorders that cause dwarfism prefer the term “little people”.) Based on this Is achondroplasia a recessive or dominant phenotype? What are the genotypes of all family members? What is the probability that a third child would be of normal stature? What is the probability that the third and fourth children would be of normal stature? Aug 3114

15. Achondroplasia is a form of dwarfism controlled by one gene with two alleles. The dominant allele causes dwarfism. Consider the Roloff family from TLC’s Little People/Big World— They have four children, three of normal stature and one with achondroplasia. What is the probability in such a family of the first child being affected and the remaining three unaffected? Aug 3115

16. Achondroplasia is a form of dwarfism controlled by one gene with two alleles. The dominant allele causes dwarfism. Consider the Roloff family from TLC’s Little People/Big World. They have four children, three of normal stature and one with achondroplasia. What is the probability that a family with two dwarf parents would have three unaffected children and one affected? Aug 3116

17. Mendel observed two traits at a time Aug 3117