Retinoblastoma is an extremely rare cancer of the retina in the eye. The disease mainly affects children up to the age of 5 years because it can only occur while the nerve precursor cells are still dividing. In its nonhereditary form, a tumor usually occurs in only one eye; in its hereditary form, multiple tumors develop in both eyes. To explore the basis for these differences, a cDNA clone of the Rb gene was used to probe the structure of the gene in cells from normal individuals and from individuals with nonhereditary or hereditary retinoblastoma. As shown in the figure Part A, normal individuals have four restriction fragments (A, B, C, and D) that hybridize to the Rb cDNA probe, indicating that each restriction fragment encodes at least one Rb exon. Samples from fibroblasts and tumor cells of affected persons show some differences in the patterns of hybridization, with some bands missing entirely and some bands present at half intensity. The order of the restriction fragments in the Rb gene is shown in Part B. Why do the band patterns differ in the fibroblasts and tumor cells from the same person? A. Tumor cells differ from fibroblasts because they have lost portions of the Rb gene. B. Tumor cells differ because they have suffered nucleotide changes in the Rb gene. C. Tumor cells differ from fibroblasts because they have inherited different Rb genes. D. Tumor cells differ because they derive from nerve cell precursors, not fibroblasts.

Human Anatomy & Physiology (11th Edition)

11th Edition

ISBN:9780134580999

Author:Elaine N. Marieb, Katja N. Hoehn

Publisher:Elaine N. Marieb, Katja N. Hoehn

Chapter1: The Human Body: An Orientation

Section: Chapter Questions

Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...

See similar textbooks

Related questions

Concept explainers

Question

Retinoblastoma is an extremely rare cancer of the retina in the eye. The disease mainly affects children up to the age of 5 years because it can only occur while the nerve precursor cells are still dividing. In its nonhereditary form, a tumor usually occurs in only one eye; in its hereditary form, multiple tumors develop in both eyes.

To explore the basis for these differences, a cDNA clone of the Rb gene was used to probe the structure of the gene in cells from normal individuals and from individuals with nonhereditary or hereditary retinoblastoma. As shown in the figure Part A, normal individuals have four restriction fragments (A, B, C, and D) that hybridize to the Rb cDNA probe, indicating that each restriction fragment encodes at least one Rb exon. Samples from fibroblasts and tumor cells of affected persons show some differences in the patterns of hybridization, with some bands missing entirely and some bands present at half intensity. The order of the restriction fragments in the Rb gene is shown in Part B.

Why do the band patterns differ in the fibroblasts and tumor cells from the same person?

A. Tumor cells differ from fibroblasts because they have lost portions of the Rb gene.

B. Tumor cells differ because they have suffered nucleotide changes in the Rb gene.

C. Tumor cells differ from fibroblasts because they have inherited different Rb genes.

D. Tumor cells differ because they derive from nerve cell precursors, not fibroblasts.

**Southern Blot Analysis (A):**

The Southern blot in panel (A) shows DNA samples from various sources that have been probed to reveal differences in gene structure. The samples are categorized from left to right as follows:

1. **Normal Fibroblasts:** Exhibits four distinct bands labeled A, B, C, and D.
2. **Person with Hereditary Retinoblastoma:**
- **Fibroblasts:** Shows reduced or absent intensity for some bands compared to normal fibroblasts.
- **Tumor Cells:** Displays further alteration in band intensity and presence.
3. **Person with Nonhereditary Retinoblastoma:**
- **Fibroblasts:** Similar to normal fibroblasts, but with slight variations in band visibility.
- **Tumor Cells:** Demonstrates significant changes in band patterns.

**Gene Structure (B):**

Panel (B) depicts the gene structure, which is segmented into four regions labeled B, D, A, and C, arranged linearly. Each segment is color-coded (B - orange, D - red, A - light green, C - green) to highlight the different parts of the gene analyzed in the Southern blot.

This figure illustrates how alterations in gene structure correspond to hereditary and nonhereditary retinoblastoma, as evidenced by differences in DNA fragment patterns.

Expert Solution

Trending now

This is a popular solution!

Step by step

Solved in 4 steps

SEE SOLUTION Check out a sample Q&A here

Knowledge Booster

Learn more about

Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.

Similar questions