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 34P
A student whose hobby was fishing pulled a very unusual carp out of Cayuga Lake: It had no scales on its body. She decided to investigate whether this strange nude phenotype had a genetic basis. She therefore obtained some inbred carp that were pure-breeding for the wild-type scale phenotype (body covered with scales in a regular pattern) and crossed them with her nude fish. To her surprise, the F1 progeny consisted of a 1:1 ratio of wild-type fish and fish with a single linear row of scales on each side.
| a. | Can a single gene with two alleles account for this result? Why or why not? |
| b. | To follow up on the first cross, the student allowed the linear fish from the F1 generation to mate with each other. The progeny of this cross consisted of fish with four |
| c. | In parallel, the student allowed the phenotypically wild-type fish from the F1 generation to mate with each other and observed, among their progeny, wild-type and scattered carp in a ratio of 3:1. How many genes with how many alleles appear to determine the difference between wild-type and scattered carp? |
| d. | The student confirmed the conclusions of (c) by crossing those scattered carp with her pure breeding wild-type stock. Diagram the genotypes and phenotypes of the parental, F1, and F2 generations for this cross and indicate the ratios observed. |
| e. | The student attempted to generate a true-breeding nude stock of fish by inbreeding. However, she found that this was impossible. Every time she crossed two nude fish, she found nude and scattered fish in the progeny, in a 2:1 ratio. (The scattered fish from these crosses bred true.) Diagram the phenotypes and genotypes of this gene in a nude × nude cross and explain the altered Mendelian ratio. |
| f. | The student now felt she could explain all of her results. Diagram the genotypes in the linear × linear cross performed by the student in (b). Show the genotypes of the four phenotypes observed among the progeny and explain the 6:3:2:1 ratio. |
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Students have asked these similar questions
A student whose hobby is fishing pulled a carp out of Cayuga Lake that was very unusual: it had no scales on its body.
She decided to investigate whether this strange “nude” phenotype had a genetic basis. She obtained some inbred carp that were pure-breeding for the wild-type scale pattern in which the fish had scales covering their body.
She crosses these wild-type fish with her nude fish. To her surprise, the F1 progeny were wild-type fish and fish with a single, linear row of scales on the sides of their body (i.e. “linear). The ratio of these progeny was 2:1.
She then crosses some of her F1 fish and obtains four phenotypes: wildtype, linear, nude and a new phenotype in which the fish had a few scales scattered over their body (i.e. “scattered”). The ratio of these offspring was 6:3:2:1.
In the space below - answer the following questions: (use the letters S/s for scale production and L/l for scale pattern)
How many genes are involved in producing scales on these fish? - answer:…
A student whose hobby was fishing pulled a very unusual carp out of Cayuga Lake: It had no scales on itsbody. She decided to investigate whether this strangenude phenotype had a genetic basis. She therefore obtained some inbred carp that were pure-breeding forthe wild-type scale phenotype (body covered withscales in a regular pattern) and crossed them with hernude fish. To her surprise, the F1 progeny consistedof a 1:1 ratio of wild-type fish and fish with a singlelinear row of scales on each side.a. Can a single gene with two alleles account for thisresult? Why or why not?b. To follow up on the first cross, the student allowedthe linear fish from the F1 generation to mate witheach other. The progeny of this cross consisted offish with four phenotypes: linear, wild type, nude,and scattered (the latter had a few scales scattered irregularly on the body). The ratio of these phenotypeswas 6:3:2:1, respectively. How many genes appear tobe involved in determining these phenotypes?c. In…
In classical Mendelian genetics, how can one check the genotype of a parent (A) expressing the characters of a dominant allele?
Select one:
a.
By performing a back cross with a recessive homozygote parent (B). If the A parent is homozygote for the dominant allele, then all the individuals from the F1 will display the dominant character. If the parent A was, instead, a heterozygote, then 50% of the F1 progeny will express the recessive character (homozygote recessive) and 50% the dominant one (heterozygotes).
b.
It is impossible to check such genotype without using specific molecular assays.
c.
By performing a back cross with a dominant homozygote parent (B). If the A parent is homozygote for the dominant allele, then all the individuals from the F1 will display the dominant character.
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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