How do our cells "create" and store energy?

Our cells create and store energy through a process called cellular respiration, specifically in the mitochondria, often referred to as the "powerhouse of the cell". Here's a step-by-step breakdown:

1. Glycolysis: This is the first step in the process of cellular respiration. It occurs in the cytoplasm of the cell. In this process, one molecule of glucose (a type of sugar) is broken down into two molecules of pyruvate. This process produces 2 ATP (adenosine triphosphate) molecules, which are used for energy.

2. Transition Reaction: The two molecules of pyruvate are then transported into the mitochondria, where they are converted into Acetyl CoA. This process also releases carbon dioxide as a byproduct.

3. Citric Acid Cycle (Krebs Cycle): The Acetyl CoA then enters the citric acid cycle, where it is broken down into carbon dioxide. This process also produces 2 ATP molecules, as well as NADH and FADH2, which are used in the next step.

4. Electron Transport Chain (ETC): The NADH and FADH2 produced in the citric acid cycle are used in the electron transport chain, which is the final step of cellular respiration. This process produces the majority of the ATP in cellular respiration, up to 34 ATP molecules. Water is also produced as a byproduct.

The ATP produced in these steps is then used as energy for various cellular processes. Any ATP that is not immediately used is stored in the cell for later use.