Cellular Respiration Introduction and Stages

Cellular Respiration Introduction

• Cellular respiration is a vital metabolic pathway on Earth.
• It is considered both elegant and fascinating, but also complex.
• The process is not daunting once understood.
• The notes will cover the process at a high level, focusing on 3 major stages.

Cellular Respiration: The Process

• Cellular respiration is the process by which living cells break down glucose molecules to release energy.
• The energy is released in the form of ATP (Adenosine Triphosphate).

Stages of Cellular Respiration

• Glycolysis:
  • Glucose, a six-carbon sugar, is chemically transformed.
  • It is converted into two molecules of pyruvate, a three-carbon molecule.
  • ATP is produced and NAD+ is converted to NADH.
  • Occurs in the cytosol (cytoplasm).
  • Aerobic and Anaerobic respiration are possible branching paths.
• Pyruvate Oxidation:
  • Pyruvate from glycolysis enters the mitochondrial matrix.
  • It's converted into a two-carbon molecule bound to Coenzyme A called acetyl CoA.
  • Carbon dioxide is released, and NAD is generated.
• Citric Acid (Krebs) Cycle:
  • Acetyl CoA combines with a four-carbon molecule and goes through a cyclical set of reactions.
  • This regenerates the four-carbon starting molecule.
  • ATP, NADH, and FADH2 are generated, and carbon dioxide is released.
• Oxidative Phosphorylation:
  • NADH and FADH2 deposit electrons in the electron transport chain.
  • Electrons move down the chain releasing energy to pump protons out of the matrix.
  • Protons flow back creating a gradient, which drives the production of ATP.
  • Oxygen accepts electrons and protons to form water.

ATP Production Summary

• Glycolysis - 2 ATPs
• Krebs Cycle - 2 ATPs
• Oxidative Phosphorylation - 34 ATPs
• Total ATP produced: 38 ATPs

This quiz covers the introduction to cellular respiration, including its significance as a metabolic pathway. It also delves into the three main stages of the process—Glycolysis, Pyruvate Oxidation, and the Krebs Cycle—highlighting key transformations and energy production methods. Understanding these stages is crucial for a comprehensive grasp of how energy is released in living cells.