A substitution mutation occurs when one nucleotide in a DNA sequence is replaced by another nucleotide.
Let's analyze the sequences provided:
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First Option:
- Original: C G T T A C T G C A A T
- Mutated: G C A A T G A C G T T A
- Analysis: The sequences differ at multiple positions, indicating more than a single change.
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Second Option:
- Original: C G T T A C T G C A A T
- Mutated: C G T G A C T G C A A T
- Analysis: The change from T to G indicates a single nucleotide substitution.
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Third Option:
- Original: C G T T A C T G C A A T
- Mutated: C G T A C T G C A A T
- Analysis: The change from T to A indicates a single nucleotide substitution.
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Fourth Option:
- Original: C G T T A C T G C A A T
- Mutated: C G T C T A C T G C A A T
- Analysis: The change from T to C indicates a single nucleotide substitution.
After analyzing these options, it appears that Second Option (C G T G A C T G C A A T) shows a substitution mutation where T (thymine) is replaced by G (guanine). The same applies to both the Third Option (C G T A C T G C A A T) and Fourth Option (C G T C T A C T G C A A T).
If you only need to select one, any of them could potentially be acceptable, but the first two options contain significant differences, while the third and fourth have clear substitutions.
If you had to choose just one clear example of a substitution mutation, you might go with Second or Third Option since they both show a single nucleotide change more explicitly.
In summary, the answers are:
- Second Option: C G T G A C T G C A A T (T to G)
- Third Option: C G T A C T G C A A T (T to A)
- Fourth Option: C G T C T A C T G C A A T (T to C)
All three contain substitution mutations, but either the third or the fourth can be a safer choice for a singular substitution.