Genetics: Analysis and Principles
6th Edition
ISBN: 9781259616020
Author: Robert J. Brooker Professor Dr.
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 6, Problem 4EQ
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?
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Students have asked these similar questions
In 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!
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 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) 75
Could you have generated a chromosome map from the F2 progeny in cross 1 (assuming you crossed F1 males and females to each other to generate the F2)? What is the advantage of using cross 2 instead?
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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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- In 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_forwardA 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?arrow_forwardThe table below shows the progeny of a test cross of a heterozygote (HhFfGg). Each row shows the number of progeny that inherited each combination of alleles from the heterozygous parent. You've already determined the gene order (G is in the middle) and labeled each type of progeny. Using this information, what is the recombination frequency between H and G? Alleles: Type: HGF hgf HgF h Gf Hgf h GF HGf hg F O 0.543 0.302 O 0.241 O 0.23 0.139 Parental Parental DCO DCO SCO (H-G) SCO (H-G) SCO (G-F) SCO (G-F) Count: 124 119 15 18 51 55 38 40 O The correct answer is not available.arrow_forward
- In a cross between mice the genotypes AB/ab x ab/ab, what is the recombination frequency if the progeny numbers are 72 AB/ab, 68 ab/ab, 17 Ab/ab, and 21 aB/ab? The alleles are shown for each chromosome, separated by a slash (/)arrow_forwardConsider the genetic map below. (a) In a total of 1000 observed progeny, how many would be expected to be parental, non-recombinant? (b) If the total number of observed double-crossover recombinant progeny is 0, what is the interference? Show step by step A-------10cm-----B—2.5cm----Carrow_forwardConsider the genetic map below. (a) In a total of 1000 observed progeny, how many would be expected to be parental, non-recombinant? (b) If the total number of observed double-crossover recombinant progeny is 0, what is the interference? Show step by step work for full credit. A-------10cm-----B—2.5cm----Carrow_forward
- Consider the genetic map below. (a) In a total of 1000 observed progeny, how many would be expected to be parental, non-recombinant? (b) If the total number of observed double-crossover recombinant progeny is 0, what is the interference? A-------20 cm-----B—5cm----Carrow_forwardYou cross two plants and get the following results: Recombinant progeny type A: 43 Recombinant progeny type B: 51 Nonrecombinant progeny type C: 129 Nonrecombinant progeny type D: 135 What is the recombination frequency? (Enter your answer as a % without the sign. For example, if your answer is 0.534, you would enter 53.4)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
- Two genes, A and B, are 10 map units apart along the same chromosome. A cross was made between AAbb and aaBB individuals to produce AaBb F1 offspring. The F1 offspring were then crossed to aabb individuals to yield an F2 generation. What would be the genotype(s) of F2 offspring that carry recombinant chromosomes? (Note: recombinant chromosomes are the product of crossing over). What percentage of F2 offspring would be Aabb?arrow_forwardA three point testcross is carried out between three linked genes. The resulting nonrecombinant progeny are d+b+k+ and dbk and the double-crossover progeny are dbk+ and d+b+k. Which is the middle locus? Show all your work. Show all possible progeny.arrow_forwardWhich of the following statement is TRUE? Recombinants cannot be formed without crossovers. Recombinants can only be formed for linked genes Recombinants can only be formed for alleles that follow independent assortment. Recombinants cannot be formed without crossovers between two linked genes. Recombinants of unlinked genes can only be formed by crossovers.arrow_forward
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