Genetic Disorders

To determine the number of "Barr Bodies" present in a somatic cell of a woman suffering from Turner syndrome, it's essential to understand what Barr Bodies are and the genetic characteristics of Turner syndrome.

Barr Body Explained:

• Barr Bodies are inactivated X chromosomes found in female cells.
• In typical females (46,XX), one of the X chromosomes is inactivated, forming one Barr Body.
• The formula for calculating Barr Bodies is: N - 1 , where N is the number of X chromosomes.

Understanding Turner Syndrome:

• Turner syndrome is a chromosomal disorder affecting females, where all or part of one of the X chromosomes is missing or altered.
• It typically presents as having only one X chromosome (45,X).
• Thus, women with Turner syndrome usually have one X chromosome and no additional X chromosome to inactivate.

Calculation of Barr Bodies:

• For an individual with Turner syndrome (45,X), N = 1.
• Therefore, the number of Barr Bodies = 1 - 1 = 0 .

Given the above explanation, the number of Barr Bodies present in a somatic cell of a woman suffering from Turner syndrome is 0. This logical deduction aligns with our understanding of chromosome behavior in Turner syndrome.

Option Analysis:

• 0: Correct. Turner syndrome typically presents with a single X chromosome, resulting in zero Barr Bodies.
• 1, 2, 3: Incorrect. These options suggest additional X chromosomes that would form Barr Bodies, which is not typical for Turner syndrome.

This question revolves around understanding genetics, particularly the inheritance of the ability to taste phenylthiocarbamide (PTC). PTC tasting is a classic example of simple Mendelian inheritance where the ability to taste PTC is determined by a dominant allele.

Let's break down the problem:

1. Genotype Explanation: In this scenario, we have two possible genotypes:
   • TT or Tt : Taster (can taste PTC).
   • tt : Non-taster (cannot taste PTC).
2. Parent Genotypes:
   • The man has a genotype TT which means he is a taster and homozygous for the taster allele.
   • The woman is a non-taster with the genotype tt .
3. Offspring Genotypes:
   • The offspring receive one allele from each parent.
   • Therefore, the children will have genotypes:
     • T (from the father) + t (from the mother) = Tt
   • Since Tt includes the dominant allele T , both offspring will be tasters.
4. Conclusion: Both the son and the daughter will have the genotype Tt and, therefore, both will be tasters. Thus, the correct option is:
   Both are tasters
   .