Essentials of Genetics - Masteringgenetic
Essentials of Genetics - Masteringgenetic
9th Edition
ISBN: 9780134143699
Author: KLUG
Publisher: PEARSON
bartleby

Concept explainers

bartleby

Videos

Textbook Question
Book Icon
Chapter 11, Problem 1CS

CASE STUDY | Art inspires learning

A genetics student visiting a museum saw a painting by Goya showing a woman with a newborn baby in her lap that had very short arms and legs along with some facial abnormalities. Wondering whether this condition might be a genetic disorder, the student went online, learning that the baby might have Roberts syndrome (RBS), a rare autosomal recessive trait. She read that cells in RBS have mitotic errors, including the premature separation of centromeres and other heterochromatic regions of homologs in metaphase instead of anaphase. As a result, metaphase chromosomes have a rigid or “railroad track” appearance. RBS has been shown to be caused by mutant alleles of the ESCO2 gene, which functions during cell division.

The student wrote a list of questions to investigate in an attempt to better understand this condition. How would you answer these questions?

What do centromeres and other heterochromatic regions have in common that might cause this appearance?

Expert Solution & Answer
Check Mark
Summary Introduction

Case summary:

On visiting the museum, the genetics student noticed a painting made by the Goya. In the painting, a woman was drawn with the baby in her lap, the baby had very little arms and legs along with some facial abnormalities. The student wonders about the condition, that it might be a genetic disorder. Through the online research, he reached to the conclusion that the baby might have RBS (Roberts syndrome), it is a rare autosomal recessive trait. In this disorder, the cells suffered from the mitotic errors that include the early separation of the centromeres and also heterochromatic regions of the homologous chromosomes at the stage of the metaphase instead of anaphase. RBS is caused by the mutated alleles of the ESCO2 gene, that has a role in the cell division.

Characters in the case:

A genetics student and a painting of a baby withvery little arms and legs along with some facial abnormalities.

Adequate information:

Facts of the case that brings in major impact are the limbs and facial abnormality in the painting of a baby, which a genetic student interpreted as RBS (Roberts syndrome) that iscaused by the mutated alleles of the ESCO2 gene.

To determine:

The common thing in between the centromere and other heterochromatic regions that causes the abnormal appearance in the RBS.

Given information:

The newborn baby had many facial abnormalities and also the length of the arms and legs are comparatively short.

Explanation of Solution

Roberts syndrome is the extremely rare genetic disorder that is due to the disrupted cell division that leads to the malformation of the bones, face, arms, legs and the skull. On chromosome number 8, a mutation in the gene ESCO2 results in the Roberts syndrome.

In a normal individual, during the cell division the copied chromosomes attach themselves to the centromeres but in RBS the newly formed chromosomes are not frequently attached themselves with the centromeres. Due to which the proper alignment of the chromosomes does not takes place.

PCS (premature chromosomal separation) occurs in the RBS as the chromosomes that are supposed to separate at the anaphase stage separates at the metaphase stage. Another chromosomal abnormality is that HR (heterochromatin repulsion), chromosomes that are having the HR experiences the heterochromatin separation at the metaphase stage. Both of these chromosomal abnormalities displays a railroad track appearance as they both lack the primary constriction and also the heterochromatin repulsion.

Conclusion

Therefore, it can be concluded that centromeres and the other heterochromatin regions both are separated at the metaphase stage that could cause the abnormality in the baby having RBS.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
Evidence [see P. G. Shiels, A. J. Kind, K. H. Campbell, et al. (1999),“Analysis of telomere lengths in cloned sheep,” Nature 399, 316–317] suggests that Dolly may have been genetically older than heractual age. As mammals age, the chromosomes in somatic cells tendto shorten from the telomeres. Therefore, older individuals haveshorter chromosomes in their somatic cells than do younger ones.When researchers analyzed the chromosomes in the somatic cells of Dolly when she was about 3 years old, the lengths of her chromosomeswere consistent with those of a sheep that was significantlyolder, say, 9–10 years old. (Note: As described in the chapter, thesheep that donated the somatic cell that produced Dolly was 6 yearsold, and her mammary cells had been grown in culture for severalcell doublings before one of the cells was fused with an oocyte.)A. Suggest an explanation why Dolly’s chromosomes seemedolder than they should have been.B. Let’s suppose that a female sheep (like Dolly), which…
Quick help!!! Only in cell biology…. Trisomy is when three copies of a chromosome are present in an organism instead of two. How do trisomies such as Trisomy 21 in Down Syndrome occur? What is the mechanism that goes wrong? During which event?
5. a. About how many molecules of histone H2A wouldbe required in a typical human cell just after thecompletion of S phase, assuming an average nucleosome spacing of 200 bp?b. During what stage of the cell cycle is it most crucial to synthesize new histone proteins?c. The human genome contains 60 histone genes,with 10–15 genes of each type (H1, H2A, H2B,H3, and H4). Why do you think the genome contains multiple copies of each histone gene?
Knowledge Booster
Background pattern image
Biology
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
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
Biology: The Dynamic Science (MindTap Course List)
Biology
ISBN:9781305389892
Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan
Publisher:Cengage Learning
Text book image
Human Heredity: Principles and Issues (MindTap Co...
Biology
ISBN:9781305251052
Author:Michael Cummings
Publisher:Cengage Learning
Text book image
Biology 2e
Biology
ISBN:9781947172517
Author:Matthew Douglas, Jung Choi, Mary Ann Clark
Publisher:OpenStax
Molecular Techniques: Basic Concepts; Author: Dr. A's Clinical Lab Videos;https://www.youtube.com/watch?v=7HFHZy8h6z0;License: Standard Youtube License