Cellular Respiration Quiz

Cellular Respiration

Glycolysis

• Occurs in the cytoplasm of cells
• Breaks down glucose (6-carbon sugar) into pyruvate (3-carbon molecule)
• Produces 2 ATP and 2 NADH molecules
• Does not require oxygen (anaerobic process)
• First step in cellular respiration

Citric Acid Cycle (Krebs Cycle)

• Occurs in the mitochondria
• Breaks down pyruvate into Acetyl-CoA, which then enters the citric acid cycle
• Produces 2 ATP, 6 NADH, and 2 FADH2 molecules
• Requires oxygen (aerobic process)
• Also known as the Krebs cycle or tricarboxylic acid (TCA) cycle

Electron Transport Chain

• Occurs in the mitochondrial inner membrane
• Transfer of electrons from high-energy molecules (NADH and FADH2) to oxygen
• Produces a proton gradient across the membrane
• Energy from the gradient is used to generate ATP

Oxidative Phosphorylation

• Occurs in the mitochondrial inner membrane
• Process by which the energy from the proton gradient is used to generate ATP
• Also known as chemiosmosis
• Most ATP molecules are generated during this stage (32-34 ATP)

Fermentation

• Occurs in the absence of oxygen (anaerobic process)
• Breaks down glucose into lactic acid or ethanol and carbon dioxide
• Produces 2 ATP molecules (less efficient than cellular respiration)
• Occurs in muscles during intense exercise and in some microorganisms

Cellular Respiration

Overview

• Cellular respiration is the process of generating energy from glucose
• It involves three main stages: glycolysis, citric acid cycle, and electron transport chain

Glycolysis

• Occurs in the cytoplasm of cells
• Breaks down glucose into pyruvate
• Produces 2 ATP and 2 NADH molecules
• Anaerobic process (does not require oxygen)
• First step in cellular respiration

Citric Acid Cycle (Krebs Cycle)

• Occurs in the mitochondria
• Breaks down pyruvate into Acetyl-CoA, which enters the citric acid cycle
• Produces 2 ATP, 6 NADH, and 2 FADH2 molecules
• Aerobic process (requires oxygen)
• Also known as Krebs cycle or tricarboxylic acid (TCA) cycle

Electron Transport Chain

• Occurs in the mitochondrial inner membrane
• Transfers electrons from high-energy molecules (NADH and FADH2) to oxygen
• Produces a proton gradient across the membrane
• Energy from the gradient is used to generate ATP

Oxidative Phosphorylation (Chemiosmosis)

• Occurs in the mitochondrial inner membrane
• Uses energy from the proton gradient to generate ATP
• Most ATP molecules are generated during this stage (32-34 ATP)

Fermentation

• Occurs in the absence of oxygen (anaerobic process)
• Breaks down glucose into lactic acid or ethanol and carbon dioxide
• Produces 2 ATP molecules (less efficient than cellular respiration)
• Occurs in muscles during intense exercise and in some microorganisms

Test your knowledge of cellular respiration, including glycolysis and the citric acid cycle, and how they generate energy for cells.