Question

the diagram shows a type of mutation in a dna strand. which term best describes the type of mutation in the dna strand? addition deletion insertion substitution

Explanation:

• In the given DNA strand, one nucleotide is replaced by another. In the original DNA, there was a 'G' (which pairs with 'C' in RNA as part of the proline - coding triplet). After mutation, the 'G' is replaced by a 'T' (which pairs with 'A' in RNA, changing the amino acid from proline to threonine).
• Addition would mean adding an extra nucleotide, increasing the length of the DNA strand. But here the length of the DNA strand (number of nucleotides) remains the same.
• Deletion would mean removing a nucleotide, decreasing the length of the DNA strand. But the length of the DNA strand (number of nucleotides) remains the same.
• Insertion is similar to addition in that it adds a new nucleotide into the DNA sequence, changing the length. But the length of the DNA strand (number of nucleotides) remains the same.
• Substitution is when one nucleotide is swapped for another. This is exactly what has happened here (a 'G' is swapped for a 'T' in the DNA strand)

Answer:

substitution