Enzymes are regulated by more than the binding of small molecules. A second method that is used all the time by eucaryotic cells to regulate a protein's function is the covalent addition of a phosphate group to one of its amino acid side chains. These phosphorylation events can affect the protein in two important ways.
I believe its A because all the other one dont make scene really.
It is the gas that comes with diarrhea.
Elbow is the joint between upper and lower arm while wrist is the joint between lower arm and hands.
So below :P
