AP BIOLOGY

Detailed explanation-1: -Transcription factors (TFs) are key regulators of intrinsic cellular processes, such as differentiation and development, and of the cellular response to external perturbation through signaling pathways. In this review we focus on the role of TFs as a link between signaling pathways and gene regulation.

Detailed explanation-2: -The molecular components of these signal transduction pathways are always activated by a chemical signaling molecule. Signaling molecules can be grouped into three classes: cell-impermeant, cell-permeant, and cell-associated signaling molecules (Figure 8.3).

Detailed explanation-3: -To date, the roles of phosphoinositide 3-kinase (PI3K)/AKT and the mitogen-activated protein kinase (MAPK) pathways in the regulation of translation are among the best understood. Both pathways engage the mechanistic target of rapamycin (mTOR) to regulate a variety of components of the translational machinery.

Detailed explanation-4: -The initiation of a signaling pathway results in a cellular response to changes in the external environment. This response can take many different forms, including protein synthesis, a change in cell metabolism, cell division and growth, or even cell death.