Question

Match List-I with List-II

List-I: Aneuploid & List-II: Genomic formula
(A). Nullisomic- Monosomic & (I). \((2n + 1) - (2n - 1)\)
(B). Double Monosomic & (II). \((2n - 1) - (2n + 1)\)
(C). Monosomic- Trisomic & (III). \((2n - 2) - (2n - 1)\)
(D). Trisomic- Monosomic & (IV). \(2n - 1 - 1\)
Choose the correct answer from the options given below:

• (A) - (III), (B) - (IV), (C) - (I), (D) - (II)
• (A) - (III), (B) - (IV), (C) - (II), (D) - (I)
• (A) - (IV), (B) - (III), (C) - (II), (D) - (I)
• (A) - (IV), (B) - (III), (C) - (I), (D) - (II)

Hint:

To distinguish between these formulas:
- Double Monosomic (\(2n - 1 - 1\)) involves two different chromosomes (e.g., losing one copy of chromosome 2 and one of chromosome 5).
- Nullisomic (\(2n - 2\)) is the loss of both copies of the same homologous chromosome pair (e.g., losing both copies of chromosome 3).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Aneuploidy is a chromosomal variation where one or more individual chromosomes are lost or gained from the diploid set (\(2n\)).
These numerical changes are represented using specific cytogenetic formulas.

Step 2: Key Formula or Approach:
Let us define the genomic formulas for the given aneuploids:
1. Monosomic: Loss of a single chromosome (\(2n - 1\)).
2. Nullisomic: Loss of a homologous chromosome pair (\(2n - 2\)).
3. Trisomic: Gain of a single extra chromosome (\(2n + 1\)).
Combinations of these changes on different chromosomes are written by combining these basic terms.

Step 3: Detailed Explanation:
Let us match the aneuploid types in List-I with their genomic formulas in List-II:
- (A). Nullisomic- Monosomic: This involves the loss of a homologous pair at one chromosome locus (\(2n - 2\)) and the loss of a single chromosome at a different locus (\(2n - 1\)). This combination is represented as \((2n - 2) - (2n - 1)\), matching (III).
- (B). Double Monosomic: This is the loss of two non-homologous chromosomes, represented as \(2n - 1 - 1\), matching (IV).
- (C). Monosomic- Trisomic: This is the loss of one chromosome at one locus and the gain of an extra chromosome at another locus, written as \((2n - 1) - (2n + 1)\), matching (II).
- (D). Trisomic- Monosomic: This is the gain of an extra chromosome at one locus and the loss of one chromosome at another locus, written as \((2n + 1) - (2n - 1)\), matching (I).
This gives the matching: (A) - (III), (B) - (IV), (C) - (II), (D) - (I).

Step 4: Final Answer:
The correct match is Option (B).