How many carbon atoms are in Acetyl-CoA?

Acetyl-CoA contains two carbon atoms. It is a key molecule in cellular respiration and acts as a crucial substrate in the citric acid cycle (also known as the Krebs cycle). Each Acetyl-CoA molecule consists of an acetyl group (which is a two-carbon fragment) that is joined to coenzyme A. This two-carbon unit is derived from the breakdown of carbohydrates, fats, and proteins during metabolic processes.

The significance of Acetyl-CoA in metabolism is profound; it is the entry point for carbon skeletons into the citric acid cycle, where it can be oxidized to produce energy in the form of ATP, along with reducing equivalents (NADH and FADH2) used in the electron transport chain. Understanding the structure and function of Acetyl-CoA is essential for grasping how energy is derived from macronutrients in cellular respiration.