Genetics: From Genes to Genomes
6th Edition
ISBN: 9781259700903
Author: Leland Hartwell Dr., Michael L. Goldberg Professor Dr., Janice Fischer, Leroy Hood Dr.
Publisher: McGraw-Hill Education
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Chapter 3, Problem 46P
This problem illustrates why classical geneticists in the days before DNA analysis usually needed to work with traits showing complete penetrance. Consider the sweet peas shown in Fig. 3.15, where the A– B– genotypic class normally produces purple flowers and all other genotypic classes have white flowers.
| a. | If the parental generation is
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| b. | Suppose now that only 75% of A– B– individuals have purple flowers (that is, the penetrance of this trait is 75%). What phenotypic ratio do you now expect among the F2 plants? |
| c. | In doing these types of crosses, what kinds of results (other than an unexpected F ratio) might suggest that penetrance of the purple |
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Assume that plant weight is determined by a pair of alleles at each of two independently assorting loci (A and a, B and b) that are additive in their effects. Further assume that each allele represented by an uppercase letter contributes 4 g to weight and that each allele represented by a lowercase letter contributes 1 g to weight. a. If a plant with genotype AA BB is crossed with a plant with genotype aa bb, what weights are expected in the F1 progeny? b. What is the distribution of weight expected in the F2 progeny?
Consider sweet peas where aabb genotypic class produces purple flowers and all other genoitypic classes have white flowers.
A)- If the parental generation is AA bb * aa BB what phenotypic ration do you expect in the F2 generation assuming complete penetrance ?
B)- suppose now that only 75% of aabb individuals have purple flowers (that is, the penetrance of this trait is 75%. what phenotypic ratio do you now expect among the F2 plants? Also, in doing these types of crosses, what other phenomena (other than incomplete dominance) could explain the phenotypic ratio answered in part b.
Assume the height in a particular plant is determined by two pairs of unlinked polygenes, each effective allele contributes 5cm to a base height of 10cm.
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Chapter 3 Solutions
Genetics: From Genes to Genomes
Ch. 3 - For each of the terms in the left column, choose...Ch. 3 - In four-oclocks, the allele for red flowers is...Ch. 3 - The Aa heterozygous snapdragons in Fig. 3.3 are...Ch. 3 - Recall from Chapter 2 Fig. 2.20 that Mendels R...Ch. 3 - In the fruit fly Drosophila melanogaster, very...Ch. 3 - A cross between two plants that both have yellow...Ch. 3 - In radishes, color and shape are each controlled...Ch. 3 - A wild legume with white flowers and long pods is...Ch. 3 - Assuming no involvement of the Bombay phenotype in...Ch. 3 - Several genes in humans in addition to the ABO...
Ch. 3 - Alleles of the gene that determines seed coat...Ch. 3 - One of your fellow students tells you that there...Ch. 3 - In a population of rabbits, you find three...Ch. 3 - In clover plants, the pattern on the leaves is...Ch. 3 - Fruit flies with one allele for curly wings Cy and...Ch. 3 - In certain plant species such as tomatoes and...Ch. 3 - In a species of tropical fish, a colorful orange...Ch. 3 - People heterozygous for normal and nonfunctional...Ch. 3 - Using old Fugate family Bibles and the Perry...Ch. 3 - A rooster with a particular comb morphology called...Ch. 3 - A black mare was crossed to a chestnut stallion...Ch. 3 - Filled-in symbols in the pedigree that follows...Ch. 3 - You perform a cross between two true-breeding...Ch. 3 - a. How would you describe inheritance of flower...Ch. 3 - Suppose the intermediate called Colorless...Ch. 3 - Explain the difference between epistasis and...Ch. 3 - The dominant allele H reduces the number of body...Ch. 3 - Secretors genotypes SS and Ss secrete their A and...Ch. 3 - Normally, wild violets have yellow petals with...Ch. 3 - A woman who is blood type B has a child whose...Ch. 3 - The following table shows the responses of blood...Ch. 3 - Three different pure-breeding strains of corn that...Ch. 3 - In mice, the AY allele of the agouti gene is a...Ch. 3 - A student whose hobby was fishing pulled a very...Ch. 3 - Suppose that blue flower color in a plant species...Ch. 3 - This problem examines possible biochemical...Ch. 3 - Considering your answers to Problem 36, does the...Ch. 3 - You picked up two mice one female and one male...Ch. 3 - Figure 3.21 and Fig. 3.28b both show traits that...Ch. 3 - Three genes in fruit flies affect a particular...Ch. 3 - The garden flower Salpiglossis sinuata painted...Ch. 3 - In foxgloves, three different petal phenotypes...Ch. 3 - In a culture of fruit flies, matings between any...Ch. 3 - Prob. 44PCh. 3 - A couple wants to know the probability that their...Ch. 3 - This problem illustrates why classical geneticists...Ch. 3 - Prob. 47PCh. 3 - Familial hypercholesterolemia FH is an inherited...Ch. 3 - You have come into contact with two unrelated...Ch. 3 - Polycystic kidney disease is a dominant trait that...Ch. 3 - Identical monozygotic twins have similar, but not...Ch. 3 - Using each of the seven coat color genes discussed...
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