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Chromosome complement of Down 's syndrom...

Chromosome complement of Down 's syndrome is
(a) 2n-1
(b) 2n-1-1
(c) 2n+1
(d) 2n+1+1

A

2n-1

B

2n-1-1

C

2n+1

D

2n+1+1

Text Solution

AI Generated Solution

The correct Answer is:
To determine the chromosome complement of Down's syndrome, we need to analyze the options provided and understand the genetic basis of the condition. ### Step-by-Step Solution: 1. **Understanding Down's Syndrome**: - Down's syndrome is a genetic disorder also known as Trisomy 21. It occurs due to the presence of an extra copy of chromosome 21. 2. **Normal Chromosome Count**: - In humans, the normal chromosome complement is represented as 2n, where 'n' is the number of pairs of chromosomes. For humans, n = 23, so 2n = 46 chromosomes. 3. **Identifying the Extra Chromosome**: - In Down's syndrome, there is an additional chromosome (the extra copy of chromosome 21). This means that instead of having the normal 46 chromosomes (2n), individuals with Down's syndrome have 47 chromosomes. 4. **Mathematical Representation**: - The presence of an extra chromosome can be represented mathematically as 2n + 1. Here, '2n' represents the normal chromosome count (46), and '+1' accounts for the additional chromosome. 5. **Evaluating the Options**: - (a) 2n - 1: This would imply one less than the normal count, which is incorrect. - (b) 2n - 1 - 1: This also implies two less than the normal count, which is incorrect. - (c) 2n + 1: This correctly represents the chromosome count in Down's syndrome, as it accounts for the extra chromosome. - (d) 2n + 1 + 1: This would imply two extra chromosomes, which is incorrect. 6. **Conclusion**: - The correct answer is (c) 2n + 1, as it accurately describes the chromosome complement of Down's syndrome. ### Final Answer: (c) 2n + 1
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