Question

the structure of atp is shown below.which feature of atp contributes the most to the large changes in free energy when atp breakdown is coupled to phosphorylation reactions?the bond between the part of the molecule with the two - ring structure and the part with the one - ring structurethe - oh at the 2 positionthe - nh₂ group attached to the two - ring structurethe repulsion between the closely packed negative charges in the three phosphate groups

Explanation:

ATP (adenosine triphosphate) has three phosphate groups. The negative charges on these phosphate groups are closely packed. Due to the like - charge repulsion (negative charges repel each other), the bonds between the phosphate groups (especially the last two, which are called high - energy bonds) are unstable. When ATP breaks down (hydrolysis) and donates a phosphate group (phosphorylation reaction), a large amount of free energy is released. The bond between the two - ring (adenine) and one - ring (ribose) structure is a normal covalent bond and does not contribute significantly to the free - energy change. The - OH at the 2' position and the - NH₂ group on adenine are also not related to the large free - energy changes during phosphorylation reactions.

Answer:

The repulsion between the closely packed negative charges in the three phosphate groups.