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Ch. 10 - Eukaryotic Chromosome Abnormalities and Molecular Organization
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
All textbooksSanders 3rd EditionCh. 10 - Eukaryotic Chromosome Abnormalities and Molecular OrganizationProblem 12a
Chapter 10, Problem 12a

A pair of homologous chromosomes in Drosophila has the following content (single letters represent genes):
Chromosome 1RNMDHBGKWU
Chromosome 2RNMDHBDHBGKWU
What term best describes this situation?

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1
Step 1: Begin by comparing the gene sequences of Chromosome 1 and Chromosome 2. Chromosome 1 has the sequence RNMDHBGKWU, while Chromosome 2 has the sequence RNMDHBDHBGKWU.
Step 2: Identify any differences between the two sequences. Notice that Chromosome 2 contains an extra segment 'DHBG' inserted between the genes 'H' and 'G'.
Step 3: Understand the concept of duplication in genetics. Duplication occurs when a segment of DNA is copied and inserted into the genome, resulting in repeated sequences.
Step 4: Recognize that the presence of the duplicated segment 'DHBG' in Chromosome 2 is a clear example of a duplication event.
Step 5: Conclude that the term best describing this situation is 'duplication,' as it refers to the repeated segment of genes in Chromosome 2 compared to Chromosome 1.

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Key Concepts

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

Homologous Chromosomes

Homologous chromosomes are pairs of chromosomes in a diploid organism that have the same structure and gene sequence but may carry different alleles. Each parent contributes one chromosome to the pair, resulting in genetic variation. In the context of Drosophila, these chromosomes can carry genes that influence traits, and their comparison can reveal important genetic relationships.
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Alleles

Alleles are different versions of a gene that can exist at a specific locus on a chromosome. They can be dominant or recessive, influencing the phenotype of an organism. In the given example, the presence of different alleles on the homologous chromosomes can lead to variations in traits among offspring, highlighting the importance of allele diversity in genetics.
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Genetic Variation

Genetic variation refers to the diversity in gene frequencies within a population. It is crucial for evolution and adaptation, as it provides the raw material for natural selection. The differences in the gene sequences of the homologous chromosomes in Drosophila suggest the presence of genetic variation, which can affect the traits expressed in the organism.
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Related Practice
Textbook Question

A researcher interested in studying a human gene on chromosome 21 and another gene on the X chromosome uses FISH probes to locate each gene. The chromosome 21 probe produces green fluorescent color, and the X chromosome probe produces red fluorescent color.

If the subject studied is female, how many green and red spots will be detected? Explain your answer.

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Textbook Question

A researcher interested in studying a human gene on chromosome 21 and another gene on the X chromosome uses FISH probes to locate each gene. The chromosome 21 probe produces green fluorescent color, and the X chromosome probe produces red fluorescent color.

If the subject studied is male, how many green and red spots will be detected? Explain your answer.

476
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Textbook Question

In what way does position effect variegation (PEV) of Drosophila eye color indicate that chromatin state can affect gene transcription?

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Textbook Question

A pair of homologous chromosomes in Drosophila has the following content (single letters represent genes):

Chromosome 1RNMDHBGKWU

Chromosome 2RNMDHBDHBGKWU

Diagram the pairing of these homologous chromosomes in prophase I.

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Textbook Question

A pair of homologous chromosomes in Drosophila has the following content (single letters represent genes):

Chromosome 1RNMDHBGKWU

Chromosome 2RNMDHBDHBGKWU

What term best describes the unusual structure that forms during pairing of these chromosomes?

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Textbook Question

A pair of homologous chromosomes in Drosophila has the following content (single letters represent genes):

Chromosome 1RNMDHBGKWU

Chromosome 2RNMDHBDHBGKWU

How does the pairing diagrammed in part (b) differ from the pairing of chromosomes in an inversion heterozygote?

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