Cellular Respiration Overview

Cellular Respiration

• Cellular respiration is the process by which cells generate energy from nutrients, converting chemical energy into ATP.
• The general equation for cellular respiration is: Glucose + Oxygen → Carbon Dioxide + Water + ATP.

Steps of Cellular Respiration

• Glycolysis: 6-carbon glucose is converted into 2 3-carbon molecules of pyruvate, producing ATP and NADH.
• Formation of Acetyl CoA: Pyruvate is oxidized into a 2-carbon molecule (acetyl CoA), producing NADH and releasing CO2.
• Citric Acid Cycle: Acetyl CoA binds to a 4-carbon molecule (oxaloacetate), producing a 6-carbon molecule (citrate), releasing energy into ATP, NADH, and FADH2.
• Electron Transport Chain: Electrons from glucose are passed through a chain of electron acceptors, pumping Hydrogen ions across the inner mitochondrial membrane, forming a proton gradient, which is used to produce ATP through chemiosmosis.

Glycolysis

• Glycolysis means "sugar splitting" and does not require oxygen.
• It involves 10 steps, converting glucose into pyruvate, producing ATP and NADH.

Formation of Acetyl CoA

• Catalyzed by enzyme pyruvate dehydrogenase.
• One carbon dioxide molecule is released, and the remaining 2-carbon fragment is oxidized, transferring electrons to NAD+.

Citric Acid Cycle

• Also known as the Tri-carboxylic acid cycle or Krebs cycle.
• Produces 6 CO2 molecules, 10 NADH molecules, and 2 FADH2 molecules per glucose molecule.

Electron Transport Chain

• Takes place in the inner mitochondrial membrane (eukaryotes) and plasma membrane (prokaryotes).
• ATP is produced through Oxidative Phosphorylation, which is coupled to redox reactions involving oxygen.

ATP Production

• Each NADH results in approximately 3 ATP.
• Each FADH2 gives 2 ATP.

Anaerobic Respiration

• Occurs in the absence of oxygen.
• Facultative anaerobes can switch between aerobic and anaerobic respiration.
• Fermentation is the anaerobic degradation of glucose, producing ATP through the conversion of glucose into lactic acid.

Examples of Anaerobic Respiration

• Lactic acid bacteria ferment glucose to lactate.
• Mammalian skeletal muscle cells ferment glucose to lactic acid during prolonged contraction when oxygen is limited.

Learn about the process of cellular respiration, where nutrients are converted into energy in the form of ATP. Explore how glucose is oxidized into carbon dioxide and oxygen is reduced into water.