A DNA segment has base order CCC ATA GCT. Which copy exhibits a deletion in the first codon triplet and then a substitution mutation?
A. CCA ATA GCT
B. CCC TAG CT
C. CCA TAG CT
D. CCA TAA CT
The original DNA sequence is CCC ATA GCT.
A deletion in the first codon triplet would involve removing one base. Therefore, the first base "C" would be deleted, leaving "CC ATA GCT".
A substitution mutation would involve replacing one base with another. The original second base "C" would be substituted with "T", resulting in "CC ATA GCT".
Among the given options, the copy that exhibits a deletion in the first codon triplet and then a substitution mutation is "CC ATA GCT".
So the correct answer is option A: CCA ATA GCT.