Textbook Question
Describe the origin of cultivated American cotton.
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Ch. 8 - Chromosome Mutations: Variation in Number and Arrangement
Klug12th EditionConcepts of Genetics ISBN: 9780135564776
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Table of contents
- Ch. 1 - Introduction to Genetics17
- Ch. 2 - Mitosis and Meiosis36
- Ch. 3 - Mendelian Genetics51
- Ch. 4 - Extensions of Mendelian Genetics74
- Ch. 5 - Chromosome Mapping in Eukaryotes51
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages46
- Ch. 7 - Sex Determination and Sex Chromosomes33
- Ch. 8 - Chromosome Mutations: Variation in Number and Arrangement40
- Ch. 9 - Extranuclear Inheritance31
- Ch. 10 - DNA Structure and Analysis43
- Ch. 11 - DNA Replication and Recombination44
- Ch. 12 - DNA Organization in Chromosomes30
- Ch. 13 - The Genetic Code and Transcription54
- Ch. 14 - Translation and Proteins47
- Ch. 15 - Gene Mutation, DNA Repair, and Transposition41
- Ch. 16 - Regulation of Gene Expression in Bacteria29
- Ch. 17 - Transcriptional Regulation in Eukaryotes41
- Ch. 18 - Post-transcriptional Regulation in Eukaryotes33
- Ch. 19 - Epigenetics33
- Ch. 20 - Recombinant DNA Technology44
- Ch. 21 - Genomic Analysis36
- Ch. 22 - Applications of Genetic Engineering and Biotechnology36
- Ch. 23 - Developmental Genetics37
- Ch. 24 - Cancer Genetics34
- Ch. 25 - Quantitative Genetics and Multifactorial Traits54
- Ch. 26 - Population and Evolutionary Genetics45
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Klug 12th EditionCh. 8 - Chromosome Mutations: Variation in Number and ArrangementProblem 7
Klug 12th EditionCh. 8 - Chromosome Mutations: Variation in Number and ArrangementProblem 7Chapter 8, Problem 7
Contrast the fertility of an allotetraploid with an autotriploid and an autotetraploid.
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Step 1: Define the terms to understand the types of polyploids involved. An allotetraploid has two different sets of chromosomes from two different species (2n from species A + 2n from species B), an autotriploid has three sets of chromosomes all from the same species (3n), and an autotetraploid has four sets of chromosomes all from the same species (4n).
Step 2: Consider how chromosome pairing occurs during meiosis in each type. In an allotetraploid, homologous chromosomes from each species pair properly because they come in sets of two, allowing for regular bivalent formation.
Step 3: Analyze the autotriploid situation. With three sets of chromosomes, homologous chromosomes cannot pair evenly during meiosis, leading to unbalanced gametes and reduced fertility.
Step 4: Examine the autotetraploid case. Since there are four homologous chromosomes from the same species, pairing can occur as multivalents or bivalents, which can lead to some irregular segregation but generally better fertility than triploids.
Step 5: Summarize the fertility outcomes based on chromosome pairing and segregation: allotetraploids tend to have high fertility due to stable bivalent pairing, autotriploids have low fertility due to irregular segregation, and autotetraploids have intermediate to high fertility depending on how chromosomes pair during meiosis.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Polyploidy and Types of Polyploids
Polyploidy refers to organisms having more than two sets of chromosomes. Autopolyploids arise from chromosome duplication within a single species, while allopolyploids result from hybridization between different species followed by chromosome doubling. Understanding these distinctions is crucial for comparing fertility among different polyploid types.
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Types of Maternal Inheritance
Chromosome Pairing and Meiosis in Polyploids
Fertility in polyploids depends on proper chromosome pairing during meiosis. Autopolyploids often have multivalent pairing due to homologous chromosomes, leading to irregular segregation and reduced fertility. Allopolyploids typically form bivalents because their chromosomes come from different species, promoting regular meiosis and higher fertility.
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Fertility Differences Among Autotriploids, Autotetraploids, and Allotetraploids
Autotriploids usually have low fertility due to unbalanced gametes from uneven chromosome segregation. Autotetraploids may have moderate fertility but can suffer from multivalent formation causing some meiotic irregularities. Allotetraploids generally exhibit higher fertility because their chromosomes pair as homologous sets, ensuring balanced gametes.
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Related Practice
Textbook Question
What evidence suggests that Down syndrome is more often the result of nondisjunction during oogenesis rather than during spermatogenesis?
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Textbook Question
For a species with a diploid number of 18, indicate how many chromosomes will be present in the somatic nuclei of individuals that are haploid, tetraploid, trisomic, and monosomic.
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Textbook Question
Inversions are said to 'suppress crossing over.' Is this terminology technically correct? If not, restate the description accurately.
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Textbook Question
What evidence indicates that humans with aneuploid karyotypes occur at conception but are usually inviable?
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Textbook Question
Predict how the synaptic configurations of homologous pairs of chromosomes might appear when one member is normal and the other member has sustained a deletion or duplication.
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