Problem 10 - Biology

Question

Individuals with trisomy \(21,\) or __________ and physically retarded and have abnormalities of the face, tongue, and eyelids. (a) Down syndrome (b) Klinefelter syndrome (c) Turner syndrome (d) Huntington's disease (e) Tay-Sachs disease

Step-by-Step Solution

Answer

Down syndrome.

Step 1: Identify the Condition

The question describes individuals with trisomy 21, which means there is an extra copy of chromosome 21.

Step 2: Associate the Description to Medical Conditions

Trisomy 21 is the specific chromosomal abnormality linked with a certain condition that affects physical and cognitive development.

Step 3: Understand Syndromes

Among the options given: - Down syndrome (Trisomy 21) is characterized by intellectual disability and distinct facial features. - Klinefelter syndrome involves an extra X chromosome. - Turner syndrome results from a missing X chromosome. - Huntington's disease is a genetic disorder affecting nerve cells in the brain. - Tay-Sachs disease affects nervous system development.

Step 4: Select the Correct Option

Based on the description provided, the correct answer that describes individuals with trisomy 21 is Down syndrome.

Key Concepts

Trisomy 21

Trisomy 21 is a genetic condition caused by the presence of an extra chromosome 21. In a typical scenario, people inherit 23 chromosomes from each parent, making 46 in total. However, in individuals with Trisomy 21, there are three copies of chromosome 21 instead of the usual two.
This is the result of an error during cell division, specifically in meiosis, when reproductive cells are being formed. One way this error occurs is through nondisjunction, where chromosomes fail to separate properly.
This leads to a cell containing an extra chromosome, which can be passed on to the offspring.

• The extra chromosome in Trisomy 21 affects every cell in the body, influencing development and function.
• Trisomy 21 is among the most common chromosomal abnormalities and occurs in roughly 1 in every 700 live births worldwide.

Trisomy 21 is synonymous with Down syndrome, as this genetic occurrence is what leads to the condition.

Down syndrome

Down syndrome is a condition that arises due to Trisomy 21. It leads to a variety of physical and cognitive developmental features. Individuals with Down syndrome often present with a set of recognizable traits or characteristics.
Some common physical aspects include:

• Characteristic facial features such as a flat facial profile, upward-slanting eyes, and a single crease across the palm (simian line).
• Developmental delays, which can range in severity and influence motor skills, speech, and learning abilities.
• Hypotonia, or reduced muscle tone, which can affect movement and posture.

Down syndrome varies from person to person. While many people with Down syndrome experience some intellectual disability, the extent of this can vary widely. Educational and social opportunities, as well as medical interventions, assist in improving the quality of life for those with Down syndrome.

Chromosomal Abnormalities

Chromosomal abnormalities occur when there are changes in the number or structure of chromosomes. Such genetic disorders are typically classified into two groups: numerical abnormalities and structural abnormalities.

• Numerical abnormalities involve the addition or loss of entire chromosomes, like Trisomy 21 (an extra chromosome 21) or Turner syndrome (a missing X chromosome).
• Structural abnormalities include duplications, deletions, or translocations within chromosomes. These structural changes can lead to various health conditions depending on which chromosomes are affected.

Chromosomal abnormalities can result from errors during cell division, such as nondisjunction, or be inherited from parents. They can manifest as mild or severe, affecting multiple systems in the body depending on the specific chromosomes involved. Diagnosing these conditions often requires genetic testing and thorough clinical assessment, helping families to understand, manage, and plan for care.