Final answer:
The single-stranded DNA sequence used to target and copy a specific DNA sequence during PCR is called a primer. Primers are essential for initiating DNA synthesis by providing a starting point for DNA polymerase to begin amplification.
Step-by-step explanation:
The single-stranded DNA that allows you to target and copy ONLY the targeted sequence is called a primer. Primers are short sequences of DNA, usually 10-20 bases long, that are designed to be complementary to the regions at the ends of the sequence to be amplified. They are crucial for the process of polymerase chain reaction (PCR), which is a technique used to amplify specific DNA fragments. The primer anneals to the template DNA and provides a starting point for DNA synthesis, allowing for the selective targeting and copying of specific DNA sequences within a complex genome.
In cloning, plasmids serve as vectors, which are tools to insert desired DNA fragments into bacterial cells for replication and further studies. These vectors are very different from primers; they host larger segments of DNA and replicate them within bacterial systems, rather than facilitating the PCR process.