Explain how cell signaling pathways in prokaryotes and eukaryotes demonstrate conservation of major features over time

Eukaryotic cells and prokaryotic cells are distant living things as they have differences even on the cellular level (i.e. the presence of a nuclear membrane, rRNA differences). Although even with these differences, the molecular biology especially for cellular metabolism and signaling pathways are conserved. One of the more common signaling pathway that is seen in both prokaryotes and eukaryotes is the G-protein pathway which involves a seven pass or serpentine protein with an intrinsic GTPase activity (hence the name) which then signal either the production of cAMP or IP3/DAG wherein these second messengers will activate certain protein kinases that will phosphorylate specific proteins and enzymes and regulate cells’ function. 

advantage of using stem cells in medical research:

1.       it provides medical benefits in the fields of therapeutic cloning and regenerative medicine.

2. it provides great potential for discovering treatments and cures to a variety of diseases including parkinson disease, spinal cord injuries, diabetes, alzheimer’s disease and many more.

3. limbs and organ could be grown in lab from stem cells and then used in transplant or treat illness.

that is wrong, its not thymus.