Question

suppose the following mutation occured in dna.
original sequence: ccc atc
mutated sequence: ccg atc
will this mutation affect the protein resulting from this gene sequence?

○ yes, all mutations change the resulting protein
○ no, the amino acid sequence has not been changed
○ no, mutations in the dna do not affect the mrna sequence
○ yes, the amino acid sequence has been changed

Explanation:

1. First, recall how DNA codes for amino acids (via mRNA transcription and codon translation). The original DNA triplet CCC and mutated CCG:

• Transcribe to mRNA: CCC → GGG, CCG → GGC.
• Now, check the amino acids: GGG codes for glycine, GGC also codes for glycine.
• So the mutation is a silent mutation (same amino acid), meaning the amino acid sequence isn’t changed.
• Analyze the options:
• "Yes, all mutations change the resulting protein" is wrong (silent mutations exist).
• "No, the amino acid sequence has not been changed" is correct (as shown by codon analysis).
• "No, mutations in the DNA do not affect the mRNA sequence" is wrong (DNA mutations do affect mRNA, but here the amino acid is same).
• "Yes, the amino acid sequence has been changed" is wrong (we saw amino acid is same).

Answer:

B. No, the amino acid sequence has not been changed