A DNA segment has base order CCC ATA GCT. Which copy exhibits a deletion in the first codon triplet and then a substitution mutation?(1 point)
CCA TAA CT
CCA ATA GCT
CCC TAG CT
CA TAG CT
CCATAACT
Which type of mutation causes cystic fibrosis?(1 point)
Cystic fibrosis is primarily caused by a mutation known as a deletion mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.
To determine the copy of the DNA segment that exhibits a deletion in the first codon triplet and a substitution mutation, we need to compare the given options with the original sequence.
Original sequence: CCC ATA GCT
Now let's evaluate each option to identify if it meets the given criteria:
1. CCA TAA CT: This option does exhibit a deletion in the first codon triplet because the "A" base in the original triplet is missing. However, it does not show a substitution mutation in any of the codons.
2. CCA ATA GCT: This option does exhibit a deletion in the first codon triplet because the first "C" base in the original triplet is missing. Additionally, it shows a substitution mutation in the second codon, where the "T" base in the original triplet is replaced by "A". Therefore, this option matches the given criteria.
3. CCC TAG CT: This option does not exhibit a deletion in the first codon triplet as all three bases are present. It also does not show a substitution mutation in any of the codons.
4. CA TAG CT: This option does exhibit a deletion in the first codon triplet because the first "C" base in the original triplet is missing. However, it does not show a substitution mutation in any of the codons.
Based on the given options, the copy of the DNA segment that exhibits a deletion in the first codon triplet and a substitution mutation is: CCA ATA GCT.