HESI A2 Biology Study Guide 2023

Cellular respiration is the process inside of cells that converts nutrients (such as sugars, amino acids, and fatty acids) into ATP (adenosine triphosphate), which is used throughout the organism for energy. Large molecules are broken into smaller molecules, which releases both energy and waste. Aerobic respiration occurs in the presence of Oxygen and has four main stages:  Glycolysis: Larger sugar molecule is broken down into 2 smaller sugar molecules in the cytoplasm. Net gain of 2 ATP and 2 NADH  Formation of Acetyl CoA: Pyruvate undergoes oxidative decarboxylation to form Acetyl coenzyme A. 1 CO2 is released as waste. Net gain of 2 NADH.  Citric acid cycle: also known as Krebs cycle. The 2 small sugar molecules produced during glycolysis are oxidized forming new products. Gain of 2 ATP, 6 NADH, 2 FADH2.  Electron transport chain: redox reaction involving the electrons removed during glycolysis and the Krebs cycle. Protons are pumped across the mitochondrial membrane to form a gradient, which drives the synthesis of 34 ATP