Table of contents
- 1. Introduction to Genetics51m
- 2. Mendel's Laws of Inheritance3h 37m
- 3. Extensions to Mendelian Inheritance2h 41m
- 4. Genetic Mapping and Linkage2h 28m
- 5. Genetics of Bacteria and Viruses1h 21m
- 6. Chromosomal Variation1h 48m
- 7. DNA and Chromosome Structure56m
- 8. DNA Replication1h 10m
- 9. Mitosis and Meiosis1h 34m
- 10. Transcription1h 0m
- 11. Translation58m
- 12. Gene Regulation in Prokaryotes1h 19m
- 13. Gene Regulation in Eukaryotes44m
- 14. Genetic Control of Development44m
- 15. Genomes and Genomics1h 50m
- 16. Transposable Elements47m
- 17. Mutation, Repair, and Recombination1h 6m
- 18. Molecular Genetic Tools19m
- 19. Cancer Genetics29m
- 20. Quantitative Genetics1h 26m
- 21. Population Genetics50m
- 22. Evolutionary Genetics29m
4. Genetic Mapping and Linkage
Mapping Genes
2:32 minutes
Problem 15b
Textbook Question
Textbook QuestionAnother cross in Drosophila involved the recessive, X-linked genes yellow (y), white (w), and cut (ct). A yellow-bodied, white-eyed female with normal wings was crossed to a male whose eyes and body were normal but whose wings were cut. The F₁ females were wild type for all three traits, while the F₁ males expressed the yellow-body and white-eye traits. The cross was carried to an F₂ progeny, and only male offspring were tallied. On the basis of the data shown here, a genetic map was constructed. Phenotype Male Offspring y + ct 9 + w + 6 y w ct 90 + + + 95 + + ct 424 y w + 376 y + + 0 + w ct 0 Construct a map, assuming that white is at locus 1.5 on the X chromosome.
Verified Solution
This video solution was recommended by our tutors as helpful for the problem above
Video duration:
2mPlay a video:
Was this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
X-linked Inheritance
X-linked inheritance refers to the pattern of inheritance for genes located on the X chromosome. In Drosophila, males have one X chromosome and one Y chromosome, while females have two X chromosomes. This means that recessive traits linked to the X chromosome are more likely to be expressed in males, as they have no second X chromosome to mask the recessive allele. Understanding this concept is crucial for analyzing the inheritance patterns in the given cross.
Recommended video:
Guided course
09:30
X-Inactivation
Phenotypic Ratios
Phenotypic ratios are the relative frequencies of different phenotypes in the offspring resulting from a genetic cross. In this case, the phenotypic ratios of male offspring provide insights into the linkage and recombination frequencies of the genes involved. By analyzing these ratios, one can infer the genetic distances between the loci on the X chromosome, which is essential for constructing a genetic map.
Recommended video:
Guided course
10:48
Mutations and Phenotypes
Genetic Mapping
Genetic mapping is the process of determining the relative positions of genes on a chromosome based on recombination frequencies. In this scenario, the data from the F₂ progeny allows for the calculation of distances between the genes yellow, white, and cut. By assuming a specific position for one gene (white at locus 1.5), one can use the observed phenotypic ratios to estimate the positions of the other genes, thereby constructing a genetic map.
Recommended video:
Guided course
11:11
Mapping Overview
Related Videos
Related Practice