how many ATP molecules are released during cellular respiration?

or what is the value of1 ATP molecule?

During cellular respiration, the actual number of ATP molecules produced can vary depending on the specific conditions and metabolic pathways involved. However, in general, the net ATP yield from one molecule of glucose during cellular respiration can be summarized as follows:

Glycolysis: During glycolysis, which occurs in the cytoplasm, a net yield of 2 ATP molecules is produced per glucose molecule.

Citric Acid Cycle (Krebs Cycle): In the presence of oxygen, the pyruvate molecules produced in glycolysis enter the mitochondria and undergo further reactions in the citric acid cycle. Here, for each glucose molecule, the net yield is about 2 ATP molecules.

Electron Transport Chain (ETC): The major ATP production occurs during the electron transport chain, also located in the mitochondria. Here, the electrons extracted from glucose are transported through a series of complexes, leading to the production of a large amount of ATP. The exact number of ATP molecules produced through the ETC varies, but approximately 28-32 ATP molecules are generated from one glucose molecule.

Therefore, the overall net yield of ATP from one glucose molecule undergoing cellular respiration is approximately 32-36 ATP molecules. Please note that these numbers are approximate averages, and different organisms may have slightly different ATP yields.

Now, to address the second part of your question - the value of one ATP molecule. ATP (adenosine triphosphate) is often referred to as the "energy currency" of the cell. It serves as a universal energy carrier, providing necessary energy for various cellular processes.

The value of one ATP molecule can be thought of as the amount of energy (or work) it can release. The hydrolysis of ATP to ADP (adenosine diphosphate) and inorganic phosphate (Pi) results in the release of energy. This energy-rich phosphate bond in ATP can be broken, providing energy for cellular activities such as muscle contraction, active transport, and synthesis of biomolecules.

The standard free energy change (∆G) for the hydrolysis of one ATP molecule under physiological conditions is approximately -7.3 kcal/mol (-30.5 kJ/mol). This indicates the amount of energy released when one ATP molecule is converted to ADP and Pi.

So, the value of one ATP molecule is the energy equivalent to approximately 7.3 kilocalories (30.5 kilojoules) of energy, which can be utilized by cells to perform various cellular functions.