Beacuse they died long time ago
The major difference is that plants use vacuoles to store excess amounts of water, while animal cells do not. A plant standing up straight compared to a plant wilting over is a result of water capacity in the vacuoles
Answer:
<h2> I don't know but my Answer is </h2><h3>from different environments ,each structure suits their environment better than the other's</h3>
Answer:
a mutation that blocks the GTPase activity of Ras
Explanation:
A G protein in inactive state is GDP bound but as soon as a guanine exchange factor (GEF) exchanges it with GTP it gets activated which means that in GTP bound state it is active. G - protein has endogenous GTPase activity. Upon interaction of GAP, the GTPase activity of this protein is exhibited. When GAP is present, hydrolysis of GTP into GDP occurs which leads to inactivation of G protein. A mutation which will block GTPase activity of Ras will therefore result in constitutive active signaling even in the absence of ligand binding to it's receptor. In such scenario, GTP will not be hydrolyzed into GDP so signaling will be up-regulated.
