Textbook Question
Both Tim and Jan have a widow's peak (see Module 9.8), but Mike has a straight hairline.
What are their genotypes?
What is the probability that Tim and Jan's next child will have freckles and a straight hairline?
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Ch. 9 Patterns of Inheritance
Taylor, Simon, Dickey, Hogan10th EditionCampbell Biology: Concepts & ConnectionsISBN: 9780136538783
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Table of contents
- Ch. 1 Biology: The Study of Scientific Life19
- Ch. 2 The Chemical Basis of Life17
- Ch. 3 The Molecules of Cells21
- Ch. 4 A Tour of the Cell20
- Ch. 5 The Working Cell17
- Ch. 6 How Cells Harvest Chemical Energy18
- Ch. 7 Photosynthesis: Using Light to Make Food15
- Ch. 8 The Cellular Basis of Reproduction and Inheritance22
- Ch. 9 Patterns of Inheritance17
- Ch. 10 Molecular Biology of the Gene13
- Ch. 11 How Genes Are Controlled13
- Ch. 12 DNA Technology and Genomics23
- Ch. 13 How Populations Evolve17
- Ch. 14 The Origin of Species19
- Ch. 15 Tracing Evolutionary History18
- Ch. 16 Microbial Life: Prokaryotes and Protists16
- Ch. 17 The Evolution of Plant and Fungal Diversity15
- Ch. 18 The Evolution of Invertebrate Diversity13
- Ch. 19 The Evolution of Vertebrate Diversity18
- Ch. 20 Unifying Concepts of Animal Structure and Function11
- Ch. 21 Nutrition and Digestion16
- Ch. 22 Gas Exchange16
- Ch. 23 Circulation17
- Ch. 24 The Immune System16
- Ch. 25 Control of Body Temperature and Water Balance20
- Ch. 26 Hormones and the Endocrine System10
- Ch. 27 Reproduction and Embryonic Development12
- Ch. 28 Nervous Systems10
- Ch. 29 The Senses12
- Ch. 30 How Animals Move19
- Ch. 31 Plant Structure, Growth, and Reproduction9
- Ch. 32 Plant Nutrition and Transport12
- Ch. 33 Control Systems in Plants15
- Ch. 34 The Biosphere: An Introduction to Earth's Diverse Environments15
- Ch. 35 Behavioral Adaptations to the Environment12
- Ch. 36 Population Ecology15
- Ch. 37 Communities and Ecosystems14
- Ch. 38 Conservation Biology14
Taylor, Simon, Dickey, Hogan10th EditionCampbell Biology: Concepts & ConnectionsISBN: 9780136538783Not the one you use?Change textbook
Chapter 9, Problem 10
A series of matings shows that the recombination frequency between the black-body gene and the gene for dumpy (shortened) wings is 36%. The recombination frequency between purple eyes and dumpy wings is 41%. What is the sequence of these three genes on the chromosome?
Verified step by step guidance1
Understand that recombination frequency is a measure of the distance between genes on a chromosome. A higher recombination frequency indicates that the genes are farther apart, while a lower recombination frequency indicates that the genes are closer together.
Identify the recombination frequencies provided in the problem: 36% between black-body and dumpy wings, and 41% between purple eyes and dumpy wings. These values will help determine the relative positions of the genes.
Recognize that the gene with the highest recombination frequency relative to the others is likely the farthest apart. Since the recombination frequency between purple eyes and dumpy wings is 41%, this suggests that purple eyes is farther from dumpy wings than black-body is from dumpy wings (36%).
To determine the sequence, consider the relative distances: black-body and dumpy wings are closer together (36%), while purple eyes is farther from dumpy wings (41%). This implies that purple eyes is on one end of the sequence, with dumpy wings in the middle, and black-body on the other side.
Conclude that the sequence of the genes on the chromosome is: black-body, dumpy wings, purple eyes. This arrangement is consistent with the recombination frequencies provided in the problem.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Recombination Frequency
Recombination frequency is a measure of the likelihood that two genes located on the same chromosome will be separated during meiosis due to crossing over. It is expressed as a percentage, indicating the proportion of offspring that exhibit recombinant phenotypes. A higher recombination frequency suggests that the genes are further apart on the chromosome, while a lower frequency indicates they are closer together.
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Allele Frequencies
Gene Mapping
Gene mapping is the process of determining the relative positions of genes on a chromosome. By analyzing recombination frequencies, scientists can create a genetic map that shows the order of genes and the distances between them. This information is crucial for understanding genetic linkage and inheritance patterns, as well as for identifying the location of genes associated with specific traits.
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04:22Map of Eukaryotic Gene Regulation
Linkage Groups
Linkage groups are sets of genes that tend to be inherited together because they are located close to each other on the same chromosome. Genes within a linkage group can influence each other's inheritance patterns due to reduced recombination between them. Understanding linkage groups helps in predicting the outcomes of genetic crosses and in constructing genetic maps that illustrate the arrangement of genes.
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Related Practice
Textbook Question
In rabbits, black hair depends on a dominant allele, B, and brown hair on a recessive allele, b. Short hair is due to a dominant allele, S, and long hair to a recessive allele, s. If a true-breeding black short-haired male is mated with a brown long-haired female, describe their offspring. What will be the genotypes of the offspring? If two of these F1 rabbits are mated, what phenotypes would you expect among their offspring? In what proportions?
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Textbook Question
A fruit fly with a gray body and red eyes (genotype BbPp) is mated with a fly having a black body and purple eyes (genotype bbpp).
What ratio of offspring would you expect if the body-color and eye-color genes are on different chromosomes (unlinked)?
When this mating is actually carried out, most of the offspring look like the parents, but 3% have a gray body and purple eyes, and 3% have a black body and red eyes.
Are these genes linked or unlinked?
What is the recombination frequency?
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Textbook Question
A couple are both phenotypically normal, but their son suffers from hemophilia, a sex-linked recessive disorder.
What fraction of their children are likely to suffer from hemophilia?
What fraction are likely to be carriers?
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Textbook Question
Why do more men than women have colorblindness?
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Textbook Question
In fruit flies, the genes for wing shape and body stripes are linked. In a fly whose genotype is WwSs, W is linked to S, and w is linked to s. Show how this fly can produce gametes containing four different combinations of alleles.
Which are parental-type gametes?
Which are recombinant gametes? How are the recombinants produced?
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