Final answer:
A transcription regulator must engage in positive control of both its own transcription and of gene expression, ensuring consistency in functional protein levels, even when initial signals fade. This involves interactions with regulatory DNA sequences and transcription factors that facilitate or block the transcription process.
Step-by-step explanation:
A transcription regulator must be able to positively control its own transcription as well as positively control gene expression even if the signal that triggered its initial expression is no longer present. These regulators can be either transcription factors such as activators, which stimulate transcription, or repressors, which inhibit transcription. Positive feedback mechanisms can ensure that once a transcription factor is produced, its concentration in the cell remains sufficient to continue its own production as well as regulate target genes, maintaining the necessary cellular function even in the absence of the initial triggering signal.
This concept is especially significant in cases where a stable state of gene expression is required over time. An example of positive regulation is a steroid hormone that acts as a positive modulator, enhancing the rate of gene expression. In terms of gene regulation, these processes involve complex interactions between regulatory DNA sequences, such as promoters, enhancers, and silencers, and the transcription machinery, including RNA polymerase and other transcription factors, in both prokaryotic and eukaryotic organisms. The detailed regulation mechanisms involve recognizing specific DNA sequence elements by transcription factors and facilitating or blocking the transcription proces