E)Krebs cycle/ cristae of mitochondria
Krebs cycle occurs inside the matrix of the mitochondria. Electron transport chain takes place in the cristae.
The answer is cholesterol
The three phases of signal transduction is (1) reception, (2) transduction, and (3) response. Reception involves the binding of a ligand, may it be a hormone or a neurotransmitter; to a receptor, may it be a membrane receptor, cytosolic receptor, or a nuclear receptor. After binding of the ligand to the receptor, there will be signal transduction of events that will ultimately form a response. For instance, insulin actin on the insulin receptor will trigger a series of events that will increase the transcription of the gene translating for glucose transporters and ultimately, increase the number of glucose transporters embedded in the cell membrane leading to increased glucose uptake in tissues.
