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
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

6. Chromosomal Variation

Chromosomal Rearrangements: Deletions

Genetics

6. Chromosomal Variation

Chromosomal Rearrangements: Deletions

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Problem 7d

Textbook Question

From the following list, identify the types of chromosome changes you expect to show phenotypic consequences.
Terminal deletion

Verified step by step guidance

Understand the concept of a terminal deletion: A terminal deletion occurs when a segment of a chromosome is lost from the end (telomeric region). This results in the loss of genetic material, which can lead to phenotypic consequences depending on the genes located in the deleted region.

Consider the impact of gene dosage: The loss of genetic material in a terminal deletion reduces the number of copies of certain genes. This can disrupt normal cellular processes and lead to phenotypic changes, especially if the deleted region contains essential or dosage-sensitive genes.

Evaluate the size of the deletion: Larger deletions are more likely to have phenotypic consequences because they involve the loss of more genes. Smaller deletions may have less noticeable effects unless they involve critical genes.

Assess the location of the deletion: The phenotypic consequences depend on whether the deleted region contains genes that are vital for development, metabolism, or other key functions. For example, deletions in regions with high gene density or essential genes are more likely to cause noticeable effects.

Consider genetic compensation and redundancy: Some genes have functional duplicates elsewhere in the genome. If the deleted region contains genes with redundant functions, the phenotypic consequences may be less severe. However, if the deleted genes are unique and essential, the effects will be more pronounced.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Chromosome Structure

Chromosomes are structures within cells that contain DNA and proteins. They are essential for the proper segregation of genetic material during cell division. Understanding chromosome structure, including the arrangement of genes and regulatory elements, is crucial for analyzing how changes can affect phenotype.

Chromosomal Deletion

A chromosomal deletion occurs when a segment of a chromosome is lost or removed. This can lead to the loss of one or more genes, potentially disrupting normal gene function and resulting in phenotypic changes. Terminal deletions specifically involve the loss of genetic material from the end of a chromosome.

Phenotypic Consequences

Phenotypic consequences refer to the observable traits or characteristics that result from genetic changes. These can include physical attributes, behaviors, and susceptibility to diseases. Understanding how specific chromosomal alterations, like deletions, can lead to changes in phenotype is essential for predicting the impact of genetic mutations.

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Related Practice

Multiple Choice

Deletions can cause what type of phenotype?

Which of the following genetic diseases is an example of a chromosomal deletion?

Human late prophase karyotypes have about 2000 visible G bands. The human genome contains approximately 22,000 genes. Consider the region 5p1.5 through the end of the short arm of chromosome 5, which is identified on the late prophase chromosome in Figure 10.5, and assume the entire region is deleted. Approximately how many genes will be lost as a result of the deletion?

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Textbook Question

From the following list, identify the types of chromosome changes you expect to show phenotypic consequences.

Interstitial deletion

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Textbook Question

The mutations called bobbed in Drosophila result from variable reductions (deletions) in the number of amplified genes coding for rRNA. Researchers trying to maintain bobbed stocks have often documented their tendency to revert to wild type in successive generations. Propose a mechanism based on meiotic recombination which could account for this reversion phenomenon. Why would wild-type flies become more prevalent in Drosophila cultures?

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Textbook Question

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. Do the karyotypes of the parents help explain the occurrence of the three previous spontaneous abortions? Explain.

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Textbook Question

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. What is the approximate probability that the next child of this couple will have cri-du-chat syndrome?

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Textbook Question

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. What segregation pattern occurred to produce the gamete involved in fertilization of the child with cri-du-chat syndrome?

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From the following list, identify the types of chromosome changes you expect to show phenotypic consequences. Terminal deletion

Key Concepts

Chromosome Structure

Chromosomal Deletion

Phenotypic Consequences

Watch next

From the following list, identify the types of chromosome changes you expect to show phenotypic consequences.
Terminal deletion