What does “energy transfer in cells” mean?

Question

ADP and ATP are involved in energy transfer in cells. I know what is ATP and I know how ADP is formed, but I don’t understand what “energy transfer in cells” means.

Answer 1

For example, we, as humans (along with all other eukaryotes) use the energy in chemical bonds (sugar for example) to power other chemical reactions (like the synthesis of proteins). This happens in our cells. Therefore, in cells, energy is transferred.