Cellular respiration is the process by which cells break down nutrients and produce ATP. The road through cellular respiration can somewhat vary, depending on the nutrient being processed; this article will focus on the pathway of breaking down glucose. There are three main stages of cellular respiration, Glycolysis, Citric Acid Cycle, and the Electron Transport System. For the chemical enthusiasts reading this, the chemical equation to describe cellular respiration is: C6H12O6 + 6O2 ®6CO2 + 6H2O + Energy (ATP and heat). Stage 1: Glycolysis The first stage is cellular respiration is called Glycolysis and occurs in the cytoplasm of the cell. This is an anaerobic activity, meaning there is no oxygen present in this stage. Like all great endeavors,
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Each time the Citric Acid Cycle is completed, 2 carbon molecules enter in the form of Acetyl CoA and those molecules exit entirely oxidized. Stage 2 Recap: We now have 2 oxidized 2 carbon molecules, 6 NADH, 2 FADH2, 6 ATP (2 from stage 1 and 4 from stage 2) and CO2. From here the products will continue onto Stage 3, the Electron Transport System. Stage 3: The Electron Transport System The Electron Transport System (also called oxidative phosphorylation and the electron transport chain) also occurs in the mitochondria in the cristae and is aerobic. During this stage, the NADH and FADH2 that were created during Glycolysis and the Citric Acid Cycle is shifted from one carrier protein (think chain) to another, losing energy along the way. Oxygen at the end of the system is pulling the NADH and FADH2 through the system like a magnet. When the oxygen at the end finally receives the electrons that are left over, water is formed. Stage 3 Recap: We now have 36 ATP, H2O, NAD and FAD+. The NAD and FAD+ will be recycled and go back to the beginning to start cellular respiration all over
Each time the Citric Acid Cycle is completed, 2 carbon molecules enter in the form of Acetyl CoA and those molecules exit entirely oxidized. Stage 2 Recap: We now have 2 oxidized 2 carbon molecules, 6 NADH, 2 FADH2, 6 ATP (2 from stage 1 and 4 from stage 2) and CO2. From here the products will continue onto Stage 3, the Electron Transport System. Stage 3: The Electron Transport System The Electron Transport System (also called oxidative phosphorylation and the electron transport chain) also occurs in the mitochondria in the cristae and is aerobic. During this stage, the NADH and FADH2 that were created during Glycolysis and the Citric Acid Cycle is shifted from one carrier protein (think chain) to another, losing energy along the way. Oxygen at the end of the system is pulling the NADH and FADH2 through the system like a magnet. When the oxygen at the end finally receives the electrons that are left over, water is formed. Stage 3 Recap: We now have 36 ATP, H2O, NAD and FAD+. The NAD and FAD+ will be recycled and go back to the beginning to start cellular respiration all over