Final answer:
Knowing the sequence of DNA before the gene of interest is essential for scientists to design appropriate primers, enabling the study and manipulation of genes for research and medical applications.
Step-by-step explanation:
Knowing the sequence of the DNA before the gene of interest allows scientists to design appropriate primers for various applications, such as polymerase chain reaction (PCR). The sequence information is crucial as specific sequences are required for the binding of polymerases, for the initiation of replication with primers, and for the initiation of transcription by promoters.
Gene sequencing methods, like chemical cleavage, enzymatic method, or oligonucleotide hybridization, help uncover the exact sequence of bases. Once known, this sequence of DNA can be used to compare with known sequences to deduce similarities, isolate specific regions of DNA, and facilitate molecular medicine by enabling targeted treatments and understanding genetic foundations of diseases.