A healthy couple with a history of three previous spontaneous abortions has just had a child with cri-du-chat syndrome, a disorder caused by a terminal deletion of chromosome 5. Their physician orders karyotype analysis of both parents and of the child. The karyotype results for chromosomes 5 and 12 are shown here. Why does this parent have a normal phenotype?
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 Rearrangements: Deletions
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Deletions can cause what type of phenotype?
A
Leaky allele
B
Psudodominance
C
Intercalary
D
Faulty

1
Understand the concept of genetic deletions: A deletion is a type of mutation where a part of the DNA sequence is missing. This can lead to various phenotypic effects depending on the genes involved.
Explore the concept of pseudodominance: Pseudodominance occurs when a recessive allele is expressed due to the deletion of the dominant allele. This can happen when the dominant allele is removed, allowing the recessive allele to manifest in the phenotype.
Consider the role of intercalary deletions: Intercalary deletions occur within the interior of a chromosome, potentially removing essential genes and leading to phenotypic changes.
Examine the concept of a leaky allele: A leaky allele is one that produces a partial function of the gene product, which can result in a less severe phenotype compared to a complete loss-of-function mutation.
Analyze faulty phenotypes: Faulty phenotypes arise when genetic deletions disrupt normal gene function, leading to abnormal traits or characteristics. This can be due to the loss of essential genes or regulatory elements.
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Chromosomal Rearrangements: Deletions practice set
