Please help me verify my answers for my midterm These questions are to guide you
ID: 86030 • Letter: P
Question
Please help me verify my answers for my midterm
These questions are to guide your studying. They do not cover oil of the topics that may be on exams. Fruit flies have two wings. A fly is heterozygous for a recessive mutation m that results in miniature (small) wings. Hence, its genotype is Mm. What is the phenotype of this fly? What are monohybrid and dihybrid crosses? Derive the genotype/phenotype ratios in a monohybrid cross AA times aa in the F_2 and F_2 generations. Starting with a blank piece of paper, derive the genotype and phenotype ratios seen in a dihybrid cross of AABB times aabb in the F_1 and F_2 generations, assuming that a and b assort independently. What types of gametes can be made by a CCDd individual? In what proportions? Predict the genotypic and phenotypic ratios in the next generation resulting from a cross between (a) two individuals of genotype Aa times aa; and (b) two individuals of genotype Yyrr and yyRr. Looking at the example of Mendel's monohybrid cross between purple-flowered and white-flowered pea plants, calculate the probability: (a) That any F_2 plant is homozygous, (b) That a white-flowered plant carries a dominant P allele, (c) That a purple-flowered plant is true-breeding, (d) That a white-flowered plant is homozygous. A husband and wife are both carriers (heterozygotes) for the recessive mutation that causes cystic fibrosis. They have three normal children and are expecting a fourth child. What is the probability that the fourth child will have the disease (i.e. is homozygous recessive)? Suppose that in mice, black fur (B) is dominant to brown (b). A second gene determines if color will occur: The dominant allele C allows color to be made, but if a mouse is homozygous for the recessive c allele, it will have white fur regardless of the genotype at the other gene. Suppose two BbCc mice are crossed together. Assuming the two genes assort independently, show that the expected phenotype ratios of their offspring are 9 black: 3 brown: 4 white.Explanation / Answer
1. If a fly is heterozygous for a recessive mutation, it means, Mm is normal. Only mm will be with small or miniature wings. Recessive mutations only express during homozygous conditions.
2. Inheritance pattern of a single trait represents monohybrid cross. Inheritance pattern of two traits represent dihybrid cross.
3. AA x aa
F1 generation Aa Aa Aa Aa
Phenotype and genotypic ration remains same.
F2 generation Aa x Aa
AA Aa Aa aa
Genotypic ratio is 1:2:1
Phenotypic ratio is 3:1