What does the SDA method primarily utilize for generating exponential amplification?

The SDA (strand displacement amplification) method primarily utilizes restriction site nicks and DNA polymerases for generating exponential amplification. This technique involves the use of a specific restriction enzyme to create nicks in a double-stranded DNA template. When a DNA polymerase recognizes these nicks, it initiates strand displacement, allowing for synthesis of new strands. This results in the amplification of the target DNA sequence due to the continuous displacement and replication of the strands.

The unique aspect of SDA is that it does not require the thermal cycling needed in traditional PCR (polymerase chain reaction) methods; instead, the process relies on enzyme activity at a constant temperature. The efficiency and sensitivity of this method make it particularly useful in molecular diagnostics.

In contrast, options that mention single strands of RNA, locked nucleic acids, and heavy metal ions do not relate directly to the fundamental mechanism of the SDA process. RNA is not the primary substrate for SDA; locked nucleic acids are modified nucleotides that can enhance hybridization but are not central to SDA; and heavy metal ions do not play a role in the amplification mechanism of SDA. Such distinctions underscore the specificity of the SDA method's reliance on the combination of restriction site nicks and the action of DNA polymerases for