Textbook Question
Why does more crossing over occur between two distantly linked genes than between two genes that are very close together on the same chromosome?
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Ch. 5 - Chromosome Mapping in Eukaryotes
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
Chapter 5, Problem 7
What is the proposed basis for positive interference?
Verified step by step guidance1
Understand that positive interference refers to the phenomenon where the occurrence of one crossover event during meiosis reduces the probability of another crossover occurring nearby on the same chromosome.
Recognize that the proposed basis for positive interference involves the physical and structural constraints of the chromosome during meiosis, particularly how the formation of one crossover influences the chromosomal environment.
Consider the role of the synaptonemal complex and the tension along the chromosome axis, which may limit the formation of additional crossovers in close proximity to an existing one.
Explore the hypothesis that crossover events trigger a signal or structural change that inhibits nearby crossover formation, ensuring crossovers are more evenly spaced along the chromosome.
Summarize that positive interference is thought to arise from mechanical and biochemical feedback mechanisms that regulate crossover distribution to maintain genetic stability and proper chromosome segregation.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Genetic Crossover
Genetic crossover is the process during meiosis where homologous chromosomes exchange segments, creating genetic diversity. This exchange occurs at points called chiasmata and is essential for proper chromosome segregation and variation in offspring.
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03:45
Descriptive Genetics
Positive Interference
Positive interference refers to the phenomenon where the occurrence of one crossover event reduces the probability of another nearby crossover on the same chromosome. This ensures crossovers are more evenly spaced, preventing clustering and promoting accurate chromosome segregation.
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07:Positional Cloning
Mechanistic Basis of Positive Interference
The proposed basis for positive interference involves structural changes in the chromosome or the synaptonemal complex after a crossover forms, which inhibits nearby crossover formation. This may involve mechanical stress relief or signaling pathways that regulate crossover distribution.
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07:Positional Cloning
Related Practice
Textbook Question
Explain why a 50 percent recovery of single-crossover products is the upper limit, even when crossing over always occurs between two linked genes?
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Textbook Question
Why are double-crossover events expected less frequently than single-crossover events?
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Textbook Question
What two essential criteria must be met in order to execute a successful mapping cross?
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Textbook Question
The genes dumpy (dp), clot (cl), and apterous (ap) are linked on chromosome II of Drosophila. In a series of two-point mapping crosses, the following genetic distances were determined. What is the sequence of the three genes?
dp–ap: 42
dp–cl: 3
ap–cl: 39
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Textbook Question
Colored aleurone in the kernels of corn is due to the dominant allele R. The recessive allele r, when homozygous, produces colorless aleurone. The plant color (not the kernel color) is controlled by another gene with two alleles, Y and y. The dominant Y allele results in green color, whereas the homozygous presence of the recessive y allele causes the plant to appear yellow. In a testcross between a plant of unknown genotype and phenotype and a plant that is homozygous recessive for both traits, the following progeny were obtained:
colored, green: 88
colored, yellow: 12
colorless, green: 8
colorless, yellow: 92
Explain how these results were obtained by determining the exact genotype and phenotype of the unknown plant, including the precise arrangement of the alleles on the homologs.
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