Final answer:
Cells control gene expression through a complex and regulated process that involves multiple stages. This control is essential for cellular function, energy conservation, and cell differentiation. Malfunctions in gene regulation can lead to serious diseases like cancer.
Step-by-step explanation:
The correct answer to the question of which best describes how cells control gene expression is D. The process of expressing genes is controlled by the cell. In both prokaryotic and eukaryotic organisms, gene expression is a tightly regulated process that is essential for the proper functioning of a cell. Cells must be able to turn genes on to produce RNA and proteins at the right times, and to turn them off when they are no longer needed.
Regulation of gene expression can happen at multiple stages, from before transcription occurs in the DNA, all the way to after a protein has been synthesized. This regulation is divided into five levels: epigenetic, transcriptional, post-transcriptional, translational, and post-translational. The evolution of eukaryotic cells added complexity to this regulation, including control over RNA levels and protein translation in different cellular compartments.
Malfunctions in gene expression can lead to diseases like cancer, highlighting the importance of precise control in these processes. The control of gene expression is crucial in conserving energy and cellular resources, and it allows for cellular differentiation in multicellular organisms.