1. What are the essential parts of a signaling pathway? -The initial signal, the receptor that binds the signal, the signalling molecule(s) that transmit the message, and the effector(s) that result in a short-term or long-term cellular change.2. How could activating a transcription factor cause long-term cellular changes? -Long-term cellular changes are caused by changes in gene transcription that result in specific proteins being made or not made; all of these signalling pathways can result in the activation of transcription factors and their movement to the nucleus to activate transcription. 3. What roles can phosphorylation play in protein function? -Phosphorylation is the most common mechanism of regulating protein function and transmitting signals throughout the cell. 4. What is the enzymatic activity of a kinase and a phosphatase? -A kinase is an enzyme that attaches a phosphate group to a protein. A phosphatase is an enzyme that removes a phosphate group from a protein. Together, these two families of enzymes act to modulate the activities of the proteins in a cell, often in response to external stimuli.5. What determines where a protein kinase or protein phosphatase will perform its enzymatic activity? -The amino acids that surround the amino acid that will be phosphorylated influence the binding of kinase and therefore influence where on the protein phosphorylation will occur.6. Why would a signaling pathway need to be regulated? -Short-term and long-term changes occur as a response to the cell’s environment, which is always subject to change. A cell must regulate which pathways are on/off in order to appropriately respond to its environment.