Final answer:
The two types of short-term cellular changes activated by signaling molecules are changes in enzyme activity and cytoskeletal organization. Phosphorylation through kinase enzymes and second messengers are key mechanisms in signaling pathways, leading to downstream cellular responses like protein synthesis and apoptosis.
Step-by-step explanation:
Short-Term Cellular Changes Due To Activated Signaling Molecules
There are primarily two types of short-term cellular changes that can occur due to an activated signaling molecule: changes in enzyme activity and changes in cytoskeletal organization. Activation of intracellular components after a ligand binds to a cell-surface receptor sets off a complex signaling pathway or cascade. During this process, enzymes such as kinases phosphorylate other proteins, altering their shape and function, thereby activating or inactivating them. Furthermore, second messengers relay signals inside the cell, and these can lead to a variety of responses, including rearrangement of the cytoskeleton, which affects the cell's shape and motility.
The propagation of a signal through phosphorylation and the action of second messengers are vital in facilitating these changes. Ultimately, such activation can result in various downstream cellular responses, like protein synthesis, metabolism changes, cell growth, or even programmed cell death, known as apoptosis. These changes are critical for the cell's ability to respond quickly to external stimuli and maintain homeostasis.