Final answer:
Transcription factors are reusable proteins that regulate gene expression by binding to DNA sequences and are not consumed in the transcription process. They can be released and reused after assisting the initiation of transcription by RNA polymerase.
Step-by-step explanation:
The transcription factors, whether positive or negative, are not 'used up' in the process of transcription. They are proteins that assist in the regulation of gene expression, and they act by binding to specific DNA sequences. After their role in the initiation of transcription by RNA polymerase is completed, they can be released and are then available to participate in another transcription event.
Particularly, in eukaryotes, multiple transcription factors are required for the recruitment of RNA polymerase to the promoter of a gene. Complexes such as TFIID are essential for this initiation process, with TFIID containing the TATA-binding protein (TBP) and other associated factors. Once RNA polymerase has initiated transcription, these factors may disassociate and be reused. Furthermore, RNA polymerase is not considered a one time use enzyme either. In bacterial cells, for instance, multiple RNA polymerases can transcribe a single gene at the same time,
Therefore, there is generally no concept of a transcription factor, including a negative one, being a single-use entity in the process of protein synthesis. They function repeatedly in the regulation of gene expression.