In Drosophila, seven partial deletions (1 to 7) shown as gaps in the following diagram have been mapped on a chromosome. This region of the chromosome contains genes that express seven recessive mutant phenotypes, identified in the following table as a through g. A researcher wants to determine the location and order of genes on the chromosome, so he sets up a series of crosses in which flies homozygous for a mutant allele are crossed with flies homozygous for a partial deletion. The progeny are scored to determine whether they have the mutant phenotype ('m' in the table) or the wild-type phenotype ('+' in the table). Use the partial deletion map and the table of progeny phenotypes to determine the order of genes on the chromosome.
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
6. Chromosomal Variation
Chromosomal Mutations: Aberrant Euploidy
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Which type of chromosomal aberration is most likely to result in a gain of function?
A
Nullisomy
B
Trisomy
C
Triploidy
D
Monosomy

1
Understand the types of chromosomal aberrations listed: Nullisomy (loss of both homologous chromosomes), Trisomy (gain of one extra chromosome), Triploidy (an entire extra set of chromosomes), and Monosomy (loss of one chromosome).
Recall that a gain of function typically results from an increase in gene dosage or the presence of an extra copy of a gene that enhances or changes the function of a gene product.
Analyze each aberration in terms of gene dosage: Nullisomy and Monosomy involve loss of genetic material, which usually leads to loss of function or reduced function, not gain.
Triploidy involves an entire extra set of chromosomes, which is often lethal and causes widespread gene dosage imbalance, but it is less specific in causing gain of function for individual genes.
Trisomy involves the gain of a single extra chromosome, which can increase the dosage of genes on that chromosome and is more likely to cause a gain of function effect for those genes.
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Chromosomal Mutations: Aberrant Euploidy practice set
