<h2>b) option is correct </h2>
Explanation:
- Some bacterial toxins cause disease by altering the activity of G protein, cholera toxin is one of them
- Cholera toxin catalyse ADP ribosylation of Gs and blocks GTPase activity thus Gs GTP become permanently active
- Constitutive activation of Gs protein continuously induce adenylyl cyclase, cytosolic cAMP level rises that leads to activation of protein kinase A (pKA)
- Activated pKA catalyse phosphorylation of two transmembrane proteins of intestinal epithelial cells:
- CFTR cause excessive outflow of Cl- ion and Na+ H+ exchange cause efflux of Na+ ion, both enters in gut and form Na+ Cl-
- Na+Cl- leads to outflow of water from the gut, resulting in diarrhea and dehydration and this condition may cause death of organisms due to loss of water and ions
<span>These cells cause the reabsorption of bone, thus helping to regenerate bone.
Hope this helps!
-Payshence xoxo</span>
When water molecules
diffuse through a cell membrane this process is called the osmosis. Water
molecules are extremely small and because of this they can slip freely through
the gaps between the phospholipids in the cell membrane. And as a result, water
molecules can constantly move back and forth though the cell <span>
membrane. This movement of water has a very important
function and that is it enables cells to absorb water. </span>
Now for a movement of
water molecules to happen, there should be a concentration gradient in the surrounding.
That is, the amount of water in one side must be different on the other side.
<span>For water to diffuse
INTO the cell, the amount of water outside the cell membrane should be larger
than the amount of water inside the side.</span>
