Cellular structures and lifestyles
are much diversified.
In spite of these differences, the same basic molecular mechanisms govern the
lives of both prokaryotes and eukaryotes,<span> the general classes of
proteins involved in signal transduction are conserved all over living cell. This is manifested through the
re-used of protein receptors, protein kinases,<span> phosphoprotein phosphates, and ion channel receptors.</span></span>
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.<span> </span>
Gravitational attraction provides the centripetal force needed to keep planets in orbit around the Sun and all types of satellite in orbit around the Earth. This means gravity makes the Moon accelerate all the time, even though its speed remains constant.
