Question

1. In the diagram below, what is not a part of an ADP molecule?

Answer 1

1.  D  ADP lacks the third phosphate group that is present in ATP.

2. D again.  The ATP molecule must be hydrolyzed to remove the third phosphate group, thus releasing energy from ATP, and creating one ADP and one Phosphate.

Answer 2

1. The right answer is D.

The diagram represents an ATP molecule.

ADP: adenosine diphosphate

ATP: adenosine triphosphate

ATP has one more phosphate than ADP. So more energy, usually in reaction that require energy, ATP is hydrolyzed to ADP + Pi (inorganic phosphate).

Basically, adenosine carries energy (for muscles, syntheses, etc.) in the form of phosphates, in ADP there are two, and in ATP there are three. So we can go from one to the other by adding or removing a phosphate.

2. The right answer is D.

The hydrolysis of ATP to ADP (adenosine diphosphate) and Pi (inorganic phosphate) is a strongly exothermic reaction. The repulsion between the negative charges of the adjacent phosphate groups makes the bonds between the first and second phosphate groups and the bonds between the second and third phosphate groups unstable. The breaking of these bonds causes a release of energy.