Cellular_Respiration._

Summary of Cellular Respiration

I. What is Cellular Respiration?

• Cellular respiration is the process by which all organisms create energy in the form of ATP by breaking down glucose molecules.

• The Formula: O2 + C6H12O6 → H2O + CO2 + Energy (ATP)

II. Stages of Cellular Respiration

A. Stage 1: Glycolysis

• Location: Cytosol of a cell

• Process: A glucose molecule is broken down using 2 ATP into:

  • 2 pyruvic acid molecules

  • 2 NADH molecules

• ATP Production: 4 ATP are produced; 2 are used, resulting in a net gain of 2 ATP.

• Summary:

  • IN: Glucose

  • OUT: 2 Pyruvate, 2 NADH, 2 ATP

B. Stage 2: Krebs Cycle

• Location: Mitochondrial matrix

• Process: 2 pyruvate molecules convert to 2 Acetyl CoA, producing:

  • 2 NADH and 4 CO2 as waste.

• Continued breakdown of 2 Acetyl CoA produces:

  • 6 NADH, 2 ATP, and 2 FADH2.

• Reactions:

  • 2 Pyruvate → 2 Acetyl CoA + 2 NADH

  • 2 Acetyl CoA → 6 NADH + 2 FADH2 + CO2

• Summary:

  • IN: 2 Pyruvate

  • OUT: 2 NADH + 6 NADH + 2 FADH2 + 2 ATP + CO2

C. Stage 3: Electron Transport Chain

• Overview: Electron carriers (NADH and FADH2) move through the electron chain,

  • Hydrogens are removed and used to produce ATP with ATP Synthase.

  • Oxygen is required in this process, producing H2O.

• Sources of NADH and FADH2:

  • 2 NADH from Glycolysis

  • 2 NADH from Acetyl CoA production

  • 6 NADH from the Krebs Cycle

  • 2 FADH2 from the Krebs Cycle

• Maximum ATP Production: 34 ATP can be produced from the electron transport chain.

• Summary:

  • IN: O2 + 2 NADH + 2 NADH + 6 NADH + 2 FADH2

  • OUT: 34 ATP and H2O

TOTAL ATP PRODUCED by Cellular Respiration: 38 ATP

III. What if Oxygen Isn’t Present?

A. Fermentation

• Definition: Breakdown of glucose or carbohydrates in the absence of oxygen.

B. Lactic Acid Fermentation

• Glycolysis occurs, yielding only 2 ATP.

• Lactic acid is produced, causing muscle fatigue and the burning sensation.

• Common example: When exercising intensely, muscles may burn due to lactic acid build-up from lack of oxygen.

• Summary of key components:

  • 2 NADH from Acetyl CoA production

  • 2 NADH from Glycolysis

  • 6 NADH from Krebs Cycle

  • 2 FADH2 from Krebs Cycle

C. Ethyl Alcohol Fermentation

• Converts pyruvic acid to ethyl alcohol (used in alcoholic beverages).

• Produces only 2 ATP.

• Applications: Used in bread, wine, and beer production.

IV. Relationship between Photosynthesis and Cellular Respiration

A. Interdependence

• Photosynthesis produces glucose and oxygen, which are reactants for cellular respiration.

• Cellular respiration generates energy, water, and carbon dioxide, which are reactants for photosynthesis.

B. In Plants

• Plants photosynthesize to produce glucose, used in cellular respiration.

• Products of cellular respiration (water and carbon dioxide) are utilized in photosynthesis.

C. In Animals

• Animals do not perform photosynthesis; they obtain glucose through consuming plants or other animals.

• This glucose is utilized in cellular respiration, producing carbon dioxide and water, which are exhaled and absorbed by plants for photosynthesis.