Question

cellular respiration is...
steps

Explanation:

To answer "Cellular Respiration is...", we recall that cellular respiration is the process by which cells break down glucose (and other nutrients) to produce ATP (energy), carbon dioxide, and water. It occurs in three main stages: glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation (electron transport chain with chemiosmosis). For the "Steps" section, we list these stages: 1. Glycolysis (in cytoplasm, breaks glucose into pyruvate, produces small ATP and NADH), 2. Pyruvate oxidation (in mitochondrial matrix, pyruvate to acetyl - CoA, produces NADH and CO₂), 3. Citric acid cycle (in mitochondrial matrix, acetyl - CoA is oxidized, produces NADH, FADH₂, ATP, and CO₂), 4. Oxidative phosphorylation (in inner mitochondrial membrane, electrons from NADH/FADH₂ pass through ETC, H⁺ gradient drives ATP synthase to make large ATP, O₂ is final electron acceptor to form H₂O).

Answer:

• Cellular Respiration is: the process by which cells break down organic molecules (like glucose) to release energy in the form of ATP, while producing carbon dioxide and water as by - products. It occurs in three main stages (glycolysis, the citric acid cycle, and oxidative phosphorylation) and is essential for the survival and function of cells as it provides the energy needed for cellular activities.
• Steps:
• Glycolysis: Occurs in the cytoplasm. Glucose (a 6 - carbon molecule) is broken down into two molecules of pyruvate (a 3 - carbon molecule). This process produces a net gain of 2 ATP molecules and 2 NADH molecules.
• Pyruvate Oxidation: Takes place in the mitochondrial matrix. Each pyruvate is converted into acetyl - CoA. During this conversion, one carbon atom is released as CO₂, and one NADH molecule is produced per pyruvate.
• Citric Acid Cycle (Krebs Cycle): Occurs in the mitochondrial matrix. Acetyl - CoA combines with oxaloacetate to form citrate. Through a series of reactions, citrate is oxidized, and for each acetyl - CoA that enters the cycle, 3 NADH, 1 FADH₂, 1 ATP (or GTP), and 2 CO₂ molecules are produced.
• Oxidative Phosphorylation: Occurs in the inner mitochondrial membrane. The NADH and FADH₂ produced in the previous steps donate electrons to the electron transport chain (ETC). As electrons pass through the ETC, H⁺ ions are pumped across the inner mitochondrial membrane, creating a proton gradient. The flow of H⁺ ions back into the mitochondrial matrix through ATP synthase drives the synthesis of ATP (about 26 - 28 ATP per glucose molecule). Oxygen acts as the final electron acceptor, combining with H⁺ ions and electrons to form water.