BIOLOGY-TEXT
5th Edition
ISBN: 9781260169621
Author: BROOKER
Publisher: MCG
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Chapter 18.6, Problem 1CC
Summary Introduction
To determine: The fly in which crossing over occurs to produce the recombinant offsprings in the F2 generation.
Introduction: During reproduction, the next generation inherits the parental traits. However, some new features are also seen in the offsprings. Linkage and crossing over are two phenomena that are responsible for the development of parental and recombinant types.
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A homozygous tomato plant with orange fruit and white flowers was crossed with a homozygous tomato plant with red fruit and red flowers. The F1 all had orange fruit and white flowers. The F1 were testcrossed by crossing them to homozygous recessive individuals and the following offspring were obtained:
Orange fruit and white flowers- 64
Red fruit and red flowers- 69
Orange fruit and red flowers- 14
Red fruit and white flowers- 13
What is the recombination frequency of these two genes?
Wild-type mice have brown fur and short tails. Loss of function of a particular gene
produces white fur, while loss of function of another gene produces long tails, and loss
of function at a third locus produces agitated behavior. Each of these loss of function
alleles is recessive. If a wild-type mouse is crossed with a triple mutant, and their F1
progeny is test-crossed, the following recombination frequencies are observed among
their progeny. Produce a genetic map for these loci.
Brown, short tailed, normal: 955
White, short tailed, normal:
16
Brown, short tailed, agitated: 0
White, short tailed, agitated: 36
Brown, long tailed, normal:
White, long tailed, normal:
Brown, long tailed, agitated:
46
0
14
White, long tailed, agitated: 933
In autotetraploid Chinese primrose (Primula sinensis L.), the gene controlling stigma color is very near the centromere of the chromosome carrying it. The allele G for green stigma is dominant to g for red stigmas. A homozygous green autotetraploid strain is crossed with a homozygous red autotetraploid strain.
a. What is the genotype of the Fl1?
b. Show the types of gametes the Fl's may be expected to form and derive the expected proportion of each. Show your solution.
c. What phenotypic ratio of green to red is expected if:
the Fl's are intercrossed? Show your solution.
the Fl's are crossed with red plants? Show your solution.
d. If the G locus were 50 or more map units from the centromere, what types and proportions of gametes would the Fl be expected to produce? Derive the expected F2 phenotypic ratio.
Chapter 18 Solutions
BIOLOGY-TEXT
Ch. 18.2 - Prob. 1CCCh. 18.3 - Prob. 1CCCh. 18.3 - Prob. 1CSCh. 18.5 - Prob. 1CSCh. 18.5 - Prob. 1CCCh. 18.6 - Prob. 1EQCh. 18.6 - Prob. 2EQCh. 18.6 - Prob. 3EQCh. 18.6 - Prob. 1CCCh. 18.6 - Prob. 2CC
Ch. 18 - Which of the following is an example of an...Ch. 18 - Prob. 2TYCh. 18 - A female mouse that is Igf2 Igf2 is crossed to a...Ch. 18 - Prob. 4TYCh. 18 - Prob. 5TYCh. 18 - Prob. 6TYCh. 18 - Prob. 7TYCh. 18 - Prob. 8TYCh. 18 - Based on the ideas proposed by Morgan, which of...Ch. 18 - Extranuclear inheritance occurs because a. certain...Ch. 18 - Define epigenetics. Are all epigenetic changes...Ch. 18 - What is a Barr body? How is its structure...Ch. 18 - Core Concept: Information A core concept of...Ch. 18 - Prob. 1COQCh. 18 - Mendel studied seven traits in garden pea plants,...
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- In your own words, explain why a testcross cannot produce more than 50% recombinant offspring. When a testcross does produce 50% recombinant offspring, what does this result mean?arrow_forwardIn an autotetraploid Chinese primrose (Primula sinensis), the gene controlling stigma color is very near the centromere of the chromosome carrying it. The allele G for green stigma is dominant to g for red stigmas. A homozygous green autotetraploid strain is crossed with a homozygous red autotetraploid strain. a. What is the genotype of the F1? b. Show the types of gametes the F1’s may be expected to form and derive the expected proportion of each. c. What phenotypic ratio of green to red is expected if: 1. The F1’s are intercrossed? 2. The F1’s are crossed with red plants d. If the G locus were 50 or more map units from the centromere, what types and proportions of gametes would the F1 be expected to produce? Derive the expected F2 phenotypic ratio.arrow_forwardIn fruit flies, red eyes (pr+_) are dominant to purple eyes (prpr) and normal wings (vg+_) are dominant to vestigial wings (vgvg). The genes are located on the same chromosome. A purebreeding red-eyed fly with vestigial wings was crossed with a pure-breeding purple-eyed fly with normal wings. All of the F1 progeny had a WT phenotype. The recombination frequency between the two genes is 15%. If an F1 individual was test crossed, what percentage of the progeny would you expect to have the WT phenotypearrow_forward
- When true-breeding mice with brown fur and short tails (BBtt)were crossed to true-breeding mice with white fur and long tails(bbTT), all of the F1 offspring had brown fur and long tails. TheF1 offspring were crossed to mice with white fur and short tails.What are the possible phenotypes of the F2 offspring? Which F2offspring are recombinant, and which are nonrecombinant? Whatare the ratios of phenotypes of the F2 offspring if independentassortment is taking place? How are the ratios affected by linkage?arrow_forwardYou are working with a hypothetical fly and have found color and wing mutants. Preliminary work indicates that the mutant traits are recessive and the associated genes are not sex-linked, but beyond that, you have no information. You first look at 2 genes, each with 2 alleles. "B" or “b" for body color and "W" or "w" for wing surface. The red-body phenotype is dominant to the yellow-body phenotype and smooth wings are dominant to crinkled wings.arrow_forwardIn the mapping example in Fig 2, the dominant alleles were on one chromosome and the recessive alleles were on the homolog. Let’s consider a twofactor cross in which the dominant allele for one gene is on onechromosome, but the dominant allele for a second gene is on thehomolog. A cross is made between AAbb and aaBB parents. The F1offspring are AaBb. The F1 heterozygotes are then testcrossed to aabbindividuals. Which F2 offspring are recombinant?arrow_forward
- Two linked loci have a recombination frequency of 5%. A series of crosses is performed. The P generation includes an individual that is homozygous dominant for trait 1 and homozygous recessive for trait 2. The second individual is homozygous recessive for trait 1 and homozygous dominant for trait 2. The F1 generation is crossed with individuals that are homozygous recessive for both traits. If 400 F2 offspring are produced, how many offspring with each phenotype are expected? Fill in the table below with your answers. Phenotype Number of Offspring Predicted Recessive 1, Recessive 2 Dominant 1, Dominant 2 Recessive 1, Dominant 2 Dominant 1, Recessive 2 Total offspring 400 For the results above, determine which phenotypes are parental and which are recombinant. Phenotype Parental or Recombinant? Dominant 1, Dominant 2 Recessive 1, Dominant 2 Recessive 1, Recessive 2 Dominant 1, Recessive 2arrow_forwardWhen true-breeding mice with brown fur and short tails (BBtt) were crossed to true-breeding mice with white fur and long tails (bbTT), all the F1 offspring had brown fur and long tails. The F1 offspring were then crossed to mice with white fur and short tails (bbtt). The fur gene and the tail length gene are 7 cM apart. Part a Which of the following F2 offspring are recombinant? (Select all that apply.) a) White fur, short tail b) Brown fur, long tail c) You need more information to answer this question. d) White fur, long tail e) Brown fur, short tail Part b Using the information given in Part a, if there were 400 mice in the F2 generation, how many do you expect would have white fur and long tails? a) 25 b) 186 c) 14 d) 372 e) 28 f) 75arrow_forwardIn letter B: If the map distance equals the number of recombinant/total of offspring, wouldn't it be 24/806 x 100? Wouldn't we add both recombinants? Can you explain letter C? I don't grasp that concept well. And since I'm using my question already, would you be able to answer D. Thank you!arrow_forward
- Hemophilia and color blindness are both recessive conditions caused by genes on the X chromosome . To calculate the recombination frequency between the two genes, you draw a large number of pedigrees that include grandfathers with both hemophilia and color blindness , their daughters (who presumably have one chromosome with two normal alleles and one chromosome with two mutant alleles), and the daughters’ sons. Analyzing all the pedigrees together shows that 25 grandsons have both color blindness and hemophilia 24 have neither of the traits , 1 has color blindness only and 1 has hemophilia only . how many centimorgans seperate the hemophilia locus from the locus of the color blindness.arrow_forwardThree linked loci are evaluated to determine the recombination frequency of the loci. To set up the test cross, an individual that is true breeding dominant for all three phenotypes is crossed with an individual that is true breeding recessive for all three phenotypes. F1 offspring are crossed with individuals that are recessive for all phenotypes. The phenotypic results are shown in the table below. Phenotype Number of Offspring Dominant 1, Dominant 2, Dominant 3 322 Dominant 1, Dominant 2, Recessive 3 82 Recessive 1, Dominant 2, Recessive 3 5 Dominant 1, Recessive 2, Dominant 3 2 Recessive 1, Dominant 2, Dominant 3 28 Recessive 1, Recessive 2, Dominant 3 89 Recessive 1, Recessive 2, Recessive 3 312 Dominant 1, Recessive 2, Recessive 3 25 1. Which two phenotypes are parental? 2. What is the map distance between locus 1 and locus 2? 3. What is the map distance between locus 1 and locus 3? 4. What is the map distance between…arrow_forwardIn a particular organism, the A locus and the D locus are so tightly linked that no crossing over is ever observed between them. If an AADD individual is crossed to an aadd individual, what types of gametes will their double-heterozygote F1 offspring produce and in what proportions? Group of answer choices 25% parental and 75% recombinant gametes 75% parental and 25% recombinant gametes 100% parental and 0% recombinant gametes 50% parental and 50% recombinant gametes 0% parental and 100% recombinant gametesarrow_forward
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