Final answer:
The given DNA sequence change represents an insertion mutation. It is a type of frameshift mutation that alters the reading frame of the codons, which can have significant effects on the resulting protein.
Step-by-step explanation:
The type of mutation being shown where the DNA sequence changes from GATTACACT to GATTACTACT is an insertion mutation, which is also considered a frameshift mutation. This is because an extra nucleotide is added to the sequence, changing the reading frame of the codons downstream in the DNA sequence. A frameshift mutation can dramatically alter the sequence of amino acids in the resulting protein, potentially leading to significant changes in protein function or stability. It is different from a silent mutation which does not change the amino acid sequence and from a point mutation which only affects a single nucleotide without shifting the reading frame.