Aerobic Respiration Overview

Aerobic Respiration Overview

• Aerobic respiration converts glucose into ATP (adenosine triphosphate) using oxygen.
• It's highly efficient, producing significantly more ATP than anaerobic respiration.
• The process has four main stages: glycolysis, link reaction, Krebs cycle, and oxidative phosphorylation.

Glycolysis

• Glycolysis is the first stage of both aerobic and anaerobic respiration.
• It occurs in the cytoplasm.
• Glucose (a 6-carbon molecule) is broken down into two pyruvate molecules (3-carbon each).
• It requires an initial investment of 2 ATP but generates 4 ATP, resulting in a net gain of 2 ATP.
• NAD+ is reduced to NADH, carrying high-energy electrons.
• Two water molecules are produced during this process.
• Two ATP and two NADH are generated per glucose molecule.

Link Reaction

• The link reaction happens in the mitochondrial matrix.
• Pyruvate from glycolysis enters the matrix.
• Pyruvate is decarboxylated (loses a carbon atom as CO2).
• The remaining two-carbon molecule combines with coenzyme A to form acetyl CoA.
• NAD+ is reduced to NADH during this conversion.
• This links glycolysis to the Krebs cycle.
• One NADH is produced per pyruvate molecule.
• One CO2 molecule is released per pyruvate.

Krebs Cycle

• The Krebs cycle (also called the citric acid cycle) takes place in the mitochondrial matrix.
• Acetyl CoA enters the cycle.
• Acetyl CoA combines with oxaloacetate to form citrate.
• A series of redox reactions releases carbon dioxide.
• NAD+ is reduced to NADH, and FAD is reduced to FADH2, both carrying high-energy electrons.
• Oxaloacetate is regenerated, enabling the cycle to continue.
• ATP is directly produced.
• One complete turn of the cycle yields 1 ATP, 3 NADH molecules, and 1 FADH2.
• Two CO2 molecules are released as waste products.

Oxidative Phosphorylation

• Oxidative phosphorylation happens in the inner mitochondrial membrane.
• Electrons from NADH and FADH2 move along an electron transport chain.
• Energy from electron transfer pumps protons (H+) across the inner membrane.
• This creates a proton gradient.
• Protons flow back across the membrane through ATP synthase.
• ATP synthesis occurs using energy from proton flow, this produces ATP from ADP and inorganic phosphate (Pi).
• Oxygen is the final electron acceptor, combining with protons to form water.

This quiz covers the key stages of aerobic respiration, detailing the conversion of glucose into ATP with oxygen. You'll explore the four main stages: glycolysis, link reaction, Krebs cycle, and oxidative phosphorylation. Test your understanding of this energy-efficient process and its components.