What role do transcription factors play in gene expression?

Transcription factors are essential proteins that bind to specific DNA sequences, playing a crucial role in the regulation of gene expression. They can either activate or repress the transcription process, which is the initial step of gene expression. By binding to promoter or enhancer regions near a gene, transcription factors facilitate or hinder the binding of RNA polymerase, the enzyme responsible for synthesizing RNA from the DNA template.

This dual functionality is vital because it allows the cell to respond to various signals and environmental changes, modulating which genes are expressed and at what levels. For instance, certain transcription factors may be activated in response to hormones, leading to the expression of specific genes necessary for the cell’s response to those hormones. Alternatively, some transcription factors might bind to repress certain genes, preventing their expression when they are not needed.

The other options do not accurately reflect the role of transcription factors in gene expression. They do not outright stop all functions of a gene, nor are they exclusively responsible for enhancing protein synthesis. Additionally, they do significantly influence gene expression, contrary to the notion that they have no impact at all.