Glucose and ATP are organic compounds composed of carbon, hydrogen and oxygen. Other than these three elements, ATP contains Phosphorus and Nitrogen. Cellular respiration breaks down glucose into water and carbon dioxide producing 38 net ATP molecules. ATP is the energy containing nucleotide in cells while the energy found in glucose is used to make ATP. The key difference between glucose and ATP is the composition of these two molecules.
What is Glucose?
Glucose is a simple sugar which is widely used in living organisms. The chemical formula of glucose is C6H12O6. It is a monosaccharide which functions as a precursor for many carbohydrates found in the organisms. In plants, glucose is produced by photosynthesis and used as a substrate for energy production. In animals, glucose is a prime energy source. In prokaryotes, glucose subjects to either aerobic respiration, anaerobic respiration, or fermentation and converts into energy molecules. Therefore, glucose can be considered as one of a primary energy source of living organisms.
Glucose is broken down completely to water and carbon dioxide by aerobic respiration. It starts with electrolysis and going via Krebs cycle and electron transport chain. In the end, it converts the energy in the nutrient glucose into 38 ATP and other two waste products. Anaerobic respiration produces less number of ATP from a glucose molecule since glucose is undergoing incomplete combustion. Some microorganisms ferment lactose to lactic acid or alcohol produce energy under anorexic conditions. All these processes use glucose as the starting substrate for ATP production.
What is ATP?
Adenosine triphosphate (ATP) is the energy currency in living cells. It is a nucleotide composed of three major components; namely, ribose sugar, triphosphate group, and adenine base. ATP molecules bear high energy within the molecules. Upon an energy request for growth and metabolism, the ATP hydrolyses and releases its energy for cellular needs. Three phosphate groups are responsible for the function of the ATP molecule because the energy is stored in ATP molecule inside the phospho-anhydride bonds between phosphate groups. The most commonly hydrolyzing phosphate group of the ATP molecule is the farthest phosphate group (Gamma-phosphate) from the ribose sugar.
ATP molecule bears high energy within it. Therefore, it is an unstable molecule. Hydrolysis of ATP is always feasible via an ergonomic reaction. The terminal phosphate group removes from the ATP molecule and converts into Adenine phosphate (ADP) when the water is present. This conversion releases 30.6 kJ/mol energy to the cells. ADP converts back into ATP immediately inside the mitochondria by ATP synthase during the cellular respiration.
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