Final answer:
Many plasmids used in biological research contain a T7 promoter for transcription by T7 RNA polymerase. In plant genetic studies, Ti plasmids, with incorporated genes of interest and T7 promoters, facilitate the creation of transgenic plants.
Step-by-step explanation:
Many plasmids in Biology research, especially those used to generate transgenic plants, contain a T7 promoter. This promoter is critical for transcription by T7 RNA polymerase, a robust enzyme originating from the T7 bacteriophage. The T7 promoter is a 19-nucleotide sequence that folds into a hairpin structure, which must be present upstream of the DNA template in the cloning vector. This design enables efficient in vitro transcription of the desired RNA. For effective transcription termination, DNA must be linearized before synthesis so that the polymerase disassociates at the cut site.
In plant genetics, the Ti plasmid from Agrobacterium tumefaciens is often employed as a shuttle vector. The gene of interest is inserted into this plasmid, which facilitates its integration into the plant cell's genome, promoting the production of transgenic plants. The T7 promoter present in these plasmids activates the transcription of the inserted genes using T7 RNA polymerase. Studies involving the T7 RNA polymerase typically utilize pre-made RNA production kits, although homemade enzyme can be used as a cost-effective alternative. Such research not only propels scientific understanding but also has practical applications in agriculture and biotechnology.