Answer: A. by preventing the production of mRNA molecules
Step-by-step explanation:
In order to control gene expression through transcription, a cell can regulate the production of mRNA molecules. This control is achieved through various mechanisms:
1. Cells can produce transcription factors that bind to specific DNA sequences called promoter regions. These transcription factors can either enhance or inhibit the binding of RNA polymerase, the enzyme responsible for transcribing DNA into mRNA. By controlling the availability and activity of transcription factors, the cell can regulate the initiation of transcription and thus control which genes are expressed.
2. The DNA in the cell is packaged into a complex called chromatin, which consists of DNA wrapped around histone proteins. The cell can modify the structure of chromatin through processes such as DNA methylation and histone modifications. These modifications can either promote or inhibit the accessibility of DNA to transcriptional machinery, thereby influencing gene expression.
3. Cells can use small RNA molecules, such as microRNAs (miRNAs) and small interfering RNAs (siRNAs), to regulate gene expression at the transcriptional level. These small RNAs can bind to mRNA molecules and prevent their translation into proteins or promote their degradation, leading to reduced expression of the corresponding genes.
While options B, C, and D are involved in other stages of gene expression or protein synthesis, they are not directly related to controlling gene expression through transcription. Therefore, the most accurate answer is option A, by preventing the production of mRNA molecules.