Question

Which of the following accurately describes the signal cascade in a typical gene regulatory network?

1) 1) environmental signal triggers transcription factor; transcription factor binds cis-regulatory element; protein coding gene activated
2) 2) environmental signal binds cis-regulatory element; cis-regulatory element triggers transcription factor; protein coding gene activated
3) 3) environmental signal triggers expression of protein coding gene; transcription factor binds cis-regulatory element; cis-regulatory element activated
4) 4) None of the above

Answer 1

The correct signal cascade in a gene regulatory network involves an environmental signal activating a transcription factor, which then binds to a cis-regulatory element, leading to the activation of a protein coding gene.

Step-by-step explanation:

The accurate description of the signal cascade in a typical gene regulatory network is 1) environmental signal triggers transcription factor; transcription factor binds cis-regulatory element; protein coding gene activated.

This sequence starts when an external environmental signal, such as a hormone, binds to a cell surface or intracellular receptor, initiating a signal transduction pathway. This leads to the activation or creation of transcription factors, which are proteins that regulate gene expression. Once activated, these transcription factors locate and bind to cis-regulatory elements, such as enhancers or silencers in the DNA, which are often proximal to or distal from the gene they regulate.

The binding of transcription factors to cis-regulatory elements then modulates the activation of protein coding genes, either increasing or decreasing transcription. This intricate process ensures that cells respond appropriately to their environment by adjusting the expression of specific genes necessary for cellular function and development.