Final answer:
The target sites of DNA-type elements are not entirely random, as specific sequence features such as inverted repeats and direct repeats affect their insertion sites, defying the belief that transposable element target sites are random.
Step-by-step explanation:
The question asks whether the target sites of DNA-type elements must be random. This is false. While there exists randomness in where transposable elements can integrate, they often have specific sequence preferences. Features like inverted repeats and direct repeats play a crucial role in the process of transposition. For example, in the maize Ac and Ds elements, there are specific sequences such as eleven base pair inverted repeats and eight base pair direct repeats of target DNA at the insertion site of transposons.
These sequences facilitate the recognition and binding of necessary enzymes for the cut-and-paste or replicative transposition mechanisms. Autonomous transposons like Ac have all required elements for transposition, including a gene for a transposase enzyme. On the other hand, non-autonomous transposons like Ds lack such a gene and hence require an autonomous element to provide the necessary enzymatic function for movement.