Down 's syndorme and Turner's syndrome are due to respectively

Options

A. Monosomic and nullisomic condition s
B. Trisomic and monosomic conditions
C. Monosomic and trisomic conditions
D. Trisomic and tetrasomic conditions

Answer

**Step-by-Step Solution:**

1. **Understanding Down's Syndrome:**
- Down's syndrome is a genetic disorder caused by the presence of an extra chromosome 21. This condition is known as trisomy 21.
- In normal circumstances, humans have two copies of each chromosome, but individuals with Down's syndrome have three copies of chromosome 21.

2. **Genotype of Down's Syndrome:**
- The typical genotype for individuals with Down's syndrome is 47 chromosomes, represented as 45 + XY (for males) or 45 + XX (for females), indicating the presence of an additional chromosome 21.

3. **Understanding Turner’s Syndrome:**
- Turner’s syndrome is a genetic disorder that occurs due to the absence of one of the X chromosomes in females. This condition is known as monosomy.
- In normal females, there are two X chromosomes (XX), but in Turner’s syndrome, there is only one X chromosome.

4. **Genotype of Turner’s Syndrome:**
- The genotype for individuals with Turner’s syndrome is represented as 44 + XO, indicating that there are 44 autosomes and only one X chromosome.

5. **Identifying the Conditions:**
- Based on the above information, Down's syndrome is due to a trisomic condition (extra chromosome), while Turner’s syndrome is due to a monosomic condition (missing chromosome).

6. **Conclusion:**
- Therefore, the correct answer to the question is that Down's syndrome is due to a trisomic condition and Turner’s syndrome is due to a monosomic condition.

**Final Answer:**
- Down's syndrome and Turner’s syndrome are due to respectively: **trisomic and monosomic conditions.**

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