Final answer:
Site-directed mutagenesis is the technique involving the use of mismatched primers to introduce mutations into a gene sequence. It's distinct from PCR, used for DNA amplification, and sequencing methods like dideoxy chain termination or shotgun sequencing, which identify the order of nucleotides in DNA.
Step-by-step explanation:
The technique that involves the addition of primers that do not exactly match the sequence of a gene to introduce a mutation is b) Site-directed mutagenesis. In site-directed mutagenesis, primers are designed to have mismatches at specific sites to introduce mutations, insertions, or deletions into a DNA sequence. This process differs from PCR (Polymerase Chain Reaction), as PCR is primarily used for amplifying DNA, not for introducing mutations. Site-directed mutagenesis is a molecular biology method that allows scientists to make precise, targeted changes to the DNA of an organism, which is useful in genetic research and biotechnology.
Looking at other molecular techniques, Southern blotting and northern blotting are two methods used for DNA and RNA detection, respectively. However, they are not used to introduce mutations. For investigating genomic disorders like sickle cell anemia, Southern blotting would be used to detect DNA polymorphism. In sequencing techniques, dideoxy chain termination and shotgun sequencing are used to determine the nucleotide sequence of DNA, which is different from site-directed mutagenesis which involves altering the sequence.