Final answer:
DAG and IP3 are produced by the cleavage of PIP2 in the plasma membrane via phospholipase C. DAG activates PKC and IP3 releases Ca2+ from the endoplasmic reticulum, both serving as second messengers in cell signaling. They do not originate from mitochondria.
Step-by-step explanation:
Diacylglycerol (DAG) and Inositol Triphosphate (IP3) are molecules that originate from the cleavage of phosphatidylinositol 4,5-bisphosphate (PIP2) by the enzyme phospholipase C. This process is part of a signaling pathway involving second messengers in cellular communication. DAG remains within the plasma membrane and is involved in activating protein kinase C (PKC), which phosphorylates certain proteins, thus influencing their functions.
IP3 is released into the cytosol, where it binds to receptors on the endoplasmic reticulum, causing the release of calcium ions (Ca2+) into the cytoplasm, triggering various cellular responses. Contrary to the part of the question mentioning mitochondria, DAG and IP3 do not originate from mitochondria, but this pathway is instead ubiquitous across almost all organisms and occurs in the plasma membrane and cytosol respectively.