Genetics: Analysis and Principles
6th Edition
ISBN: 9781259616020
Author: Robert J. Brooker Professor Dr.
Publisher: McGraw-Hill Education
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Chapter 6, Problem 4CONQ
Mitotic recombination can occasionally produce a twin spot. Let’s suppose an animal species is heterozygous for two genes that govern fur color and length: one gene affects pigmentation, with dark pigmentation (A) dominant to albino (a); the other gene affects hair length, with long hair (L) dominant to short hair (l). The two genes are linked on the same chromosome. Let’s assume an animal of this species is
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Chapter 6 Solutions
Genetics: Analysis and Principles
Ch. 6.1 - 1. Genetic linkage occurs because
a. genes that...Ch. 6.1 - In the experiment by Bateson and Punnett, which of...Ch. 6.2 - Prob. 1COMQCh. 6.2 - Prob. 2COMQCh. 6.2 - 3. For a chi square analysis involving genes that...Ch. 6.3 - Answer the multiple-choice questions based on the...Ch. 6.3 - Answer the multiple-choice questions based on the...Ch. 6.4 - 1. A tetrad of spores in an ascus is the product...Ch. 6.4 - Prob. 2COMQCh. 6.5 - 1. The process of mitotic recombination involves...
Ch. 6 - 1. What is the difference in meaning between the...Ch. 6 - 2. When a chi square analysis is applied to solve...Ch. 6 - 3. What is mitotic recombination? A heterozygous...Ch. 6 - 4. Mitotic recombination can occasionally produce...Ch. 6 - 5. A crossover has occurred in the bivalent shown...Ch. 6 - A crossover has occurred in the bivalent shown...Ch. 6 - A diploid organism has a total of 14 chromosomes...Ch. 6 - If you try to throw a basketball into a basket,...Ch. 6 - 9. By conducting testcrosses, researchers have...Ch. 6 - In humans, a rare dominant disorder known as...Ch. 6 - 11. When true-breeding mice with brown fur and...Ch. 6 - Though we often think of genes in terms of the...Ch. 6 - 13. If the likelihood of a single crossover in a...Ch. 6 - 14. In most two-factor crosses involving linked...Ch. 6 - Researchers have discovered that some regions of...Ch. 6 - 16. Describe the unique features of ascomycetes...Ch. 6 - Figure 6.1 shows the first experimental results...Ch. 6 - In the experiment of Figure 6.6, Stern followed...Ch. 6 - 3. Explain the rationale behind a testcross. Is it...Ch. 6 - 4. In your own words, explain why a testcross...Ch. 6 - Explain why the percentage of recombinant...Ch. 6 - 6. If two genes are more thanapart, how would you...Ch. 6 - 7. In Morgan’s three-factor crosses of Figure 6.3,...Ch. 6 - Two genes are located on the same chromosome and...Ch. 6 - 9. Two genes, designated A and B, are locatedfrom...Ch. 6 - 10. Two genes in tomatoes areapart; normal fruit...Ch. 6 - In the tomato, three genes are linked on the same...Ch. 6 - A trait in garden peas involves the curling of...Ch. 6 - Prob. 13EQCh. 6 - 14. In the garden pea, several different genes...Ch. 6 - A sex-influenced trait is dominant in males and...Ch. 6 - Three recessive traits in garden pea plants are as...Ch. 6 - In mice, a trait called snubnose is recessive to a...Ch. 6 - 18. In Drosophila, an allele causing vestigial...Ch. 6 - 19. Three autosomal genes are linked along the...Ch. 6 - 20. Let’s suppose that two different X-linked...Ch. 6 - Prob. 21EQCh. 6 - In mice, a dominant allele that causes a short...Ch. 6 - 2. In Chapter 3, we discussed the idea that the X...Ch. 6 - Mendel studied seven traits in pea plants, and the...
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- Consider three genes on the same chromosome, Gene A, Gene B and Gene C. You perform three factor mapping cross between parentals aaBBCC and AAbbcc, and then cross the F1 triheterozygotes (aABbCc) to a pure breeding homozygous recessive strain (aabbcc). Indicate whether the F2 offspring below resulted from parental or recombinant gametes.arrow_forwardDetermine the linear order of the genes on the chromosome (which gene is in the middle?).arrow_forwardWild-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: 933arrow_forward
- Genes a and b are 20 cM apart. An a+ b+/a+ b+ individual was mated with an a b/a b individual.(a) Diagram the cross and show the gametes produced by each parent and the genotype of the F1.(b) What gametes can the F1 produce, and in what proportions?(c) If the F1 was crossed to a b/a b individuals, what off-spring would be expected, and in what proportions?(d) Is this an example of the coupling or repulsion link-age phase?(e) If the F1 were intercrossed, what offspring would be expected, and in what proportions?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_forwardThe genes S and T show complete linkage. If a heterozygous individual (whose parents were SSTT x sstt) were to produce gametes, which distribution below is most likely? a) S,s,T and t gametes in a 1:1:1:1 ratio b) ST and st gametes in a 1:1 RATIO c) ST, St, sT and st gametes in a 1:1:1:1 ratio d) SsTt gamete is the only type producedarrow_forward
- A cross in Drosophila melanogaster involved the recessive X-linked genes for white eye (w), yellow body (y), and cut wings (c). A wild-type tri-hybrid female was crossed with wild-type males and only the male offspring were tallied. On the basis of the results shown below, which of the choices shown best represents the genetic map of the three loci on the X-chromosome? Phenotype Male Offspring + y ct 494 w + + 394 + + ct 28 w y + 35 + y + 105 w + ct 101 w y ct 5 + + + 3arrow_forwardIn dogs, three STRP loci are linked on the long arm of the X chromosome (in the order centromere-A-B-C-telomere). In the pedigree shown below, each individual was genotyped for the 3 markersand bands identified on a gel are shown beneath each individual.a. Why do males always have just one allele at each locus? Why do females sometimes have oneand sometimes have two?b. Which individuals have recombinant haplotypes?c. For each recombinant individual in generation III, identify where the recombination events tookplace (between which loci AND in which parent).d. Draw a map showing the genetic distances between the three loci, based on the informationyou havearrow_forwardA new gene is being investigated in fruit flies. The recessive allele of this gene (b) causes the wings to develop a blue color, while the dominant allele (b+) permits wild-type colorless wings to develop. Preliminary studies indicate that this new gene is located on the X-chromosome. You decided to perform a two-point testcross to determine its positionrelative to the well-established garnet eyes gene (g). You cross a female heterozygous for both genes with a testcross male fly and obtain the male offspring results shown in table 1, below. Is the original female a coupling or repulsion heterozygote? What is the map distance between genes b and g?. Based on these results, gene b must be located between what two genes on the map? You perform another two-point testcross between gene b and gene v and obtained the results in table 2, below. Now, you can localize gene b to be specifically between which two genes?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 (map units) separate the hemophilia locus from the locus for color blindness?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_forwardBased on the data in Table 1, which individual(s) is/are heterozygous? Select all that apply a) B IV-8 b) C IV-3 c) B IV-9 d) A IV-3arrow_forward
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