Stages of Cellular Respiration

The diagram illustrates the steps of cellular respiration in mitochondria, providing a comprehensive cellular respiration diagram. It shows where cellular respiration takes place and outlines the three stages of cellular respiration.

Definition: Cellular respiration is the process by which cells break down glucose to produce energy in the form of ATP.

The process begins with glycolysis in the cytosol, followed by pyruvate oxidation and the Krebs cycle in the mitochondrial matrix, and concludes with the electron transport chain and oxidative phosphorylation in the inner mitochondrial membrane.

Vocabulary: Glycolysis literally means "to split glucose" and occurs in the cytosol.

Glycolysis breaks down one glucose molecule (C₆H₁₂O₆) into two pyruvate molecules (C₃H₃O₃), producing a net gain of 2 ATP through substrate-level phosphorylation and reducing NAD+ to NADH.

Example: The cellular respiration equation for glycolysis can be summarized as: Glucose + 2 NAD⁺ + 2 ADP + 2 Pi → 2 Pyruvate + 2 NADH + 2 ATP + 2 H⁺ + 2 H₂O

Pyruvate oxidation occurs as the pyruvate molecules enter the mitochondria. This step produces Acetyl-CoA, NADH, and CO₂. The Krebs cycle, also known as the citric acid cycle, then further breaks down the Acetyl-CoA, producing more NADH, FADH₂, and CO₂.

Highlight: The Krebs cycle is a crucial part of cellular respiration, producing electron carriers (NADH and FADH₂) that will be used in the electron transport chain.

The electron transport chain and oxidative phosphorylation represent the final stage of cellular respiration. This process uses the electron carriers produced in earlier stages to create a proton gradient across the inner mitochondrial membrane. This gradient drives ATP synthesis through chemiosmosis.

Vocabulary: Chemiosmosis is the process by which ATP is produced using the energy from the proton gradient.

Oxygen serves as the final electron acceptor in this process, combining with hydrogen ions to form water. This is why cellular respiration is important in aerobic organisms, as it allows for the most efficient extraction of energy from glucose.

Quote: "26-28 ATP = Oxidative phosphorylation"

The diagram shows that the total ATP yield from one glucose molecule through aerobic cellular respiration is 30-32 ATP. This includes 2 ATP from glycolysis, 2 ATP from the Krebs cycle $both through substrate-level phosphorylation$, and 26-28 ATP from oxidative phosphorylation.

Understanding these stages of cellular respiration and the cellular respiration diagram is crucial for grasping how cells produce energy efficiently. This process demonstrates the intricate mechanisms that allow organisms to utilize the energy stored in glucose molecules to power various cellular functions.