Chapter 8, Problem 12A

Summary Introduction

To describe:

How energy is released from ATP.

Introduction:

There are many forms of energy like light energy, mechanical energy, heat energy and chemical energy. In living organisms, chemical energy is stored in organic compounds and this energy is converted to other forms of energy. Adenosine triphosphate or ATP is the most important biological molecule that provides chemical energy.

Answer to Problem 12A

Catabolic pathways release energy by breaking down larger molecules into smaller molecules. ATP is the most abundant energy molecule that releases energy when the bond between second and third phosphate groups break forming adenosine diphosphate or ADP.

Explanation of Solution

ATP is a multipurpose storehouse of chemical energy that can be used by cells in a variety of reactions. There are other carrier molecules also but ATP is the most abundant carrier molecule for energy in cells. These are found in all types of organisms. An ATP molecule is made of an adenine base, a ribose sugar and three phosphate groups. The breakdown of ATP releases energy for powering cellular activities in organisms. Hence it is called energy currency of a cell.

The bond between second and third phosphate groups in ATP molecule is highly energetic. It releases energy when this bond between second and third phosphate groups breaks forming adenosine diphosphate or ADP and a free phosphate group. A lot of energy is released which can be used by the cells to perform various activities.