Cellular respiration

Definition

Cellular respiration is the process by which cells convert glucose and oxygen into energy, carbon dioxide, and water. This process is crucial for producing adenosine triphosphate (ATP), which serves as the main energy currency of cells. Cellular respiration involves a series of metabolic reactions that occur in different parts of the cell, including the mitochondria, allowing for efficient energy production essential for various cellular functions.

5 Must Know Facts For Your Next Test

1. Cellular respiration can occur in both aerobic (with oxygen) and anaerobic (without oxygen) conditions, with aerobic respiration yielding more ATP than anaerobic processes.
2. The three main stages of cellular respiration are glycolysis, the Krebs cycle (or citric acid cycle), and oxidative phosphorylation.
3. During glycolysis, one molecule of glucose is converted into two molecules of pyruvate, generating a net gain of 2 ATP molecules.
4. The Krebs cycle occurs in the mitochondria and produces electron carriers NADH and FADH2, which are essential for the next stage of cellular respiration.
5. Oxidative phosphorylation involves the electron transport chain and chemiosmosis, where ATP is synthesized using the energy released from electrons moving through the chain.

Review Questions

• What are the main stages of cellular respiration, and how do they contribute to energy production?
  • The main stages of cellular respiration are glycolysis, the Krebs cycle, and oxidative phosphorylation. Glycolysis breaks down glucose into pyruvate while producing a small amount of ATP. The Krebs cycle further processes pyruvate in the mitochondria, generating electron carriers that fuel oxidative phosphorylation. During oxidative phosphorylation, ATP is produced through a series of reactions in the electron transport chain, ultimately leading to efficient energy conversion for cellular functions.
• Compare and contrast aerobic and anaerobic respiration regarding their processes and energy yields.
  • Aerobic respiration requires oxygen and proceeds through all three stages: glycolysis, the Krebs cycle, and oxidative phosphorylation. It produces a high yield of ATP, typically around 36-38 ATP molecules per glucose molecule. In contrast, anaerobic respiration occurs without oxygen and only involves glycolysis followed by fermentation processes, resulting in much lower ATP yields, usually around 2 ATP molecules per glucose molecule. This difference highlights the efficiency of aerobic respiration in energy production.
• Evaluate the importance of mitochondria in cellular respiration and how their structure facilitates this process.
  • Mitochondria are essential for cellular respiration as they are the sites where key processes like the Krebs cycle and oxidative phosphorylation take place. Their unique double-membrane structure allows for compartmentalization; the inner membrane houses the electron transport chain while creating a space for proton accumulation, essential for ATP synthesis. This structural design enhances energy production efficiency by facilitating electron transfer and ATP generation through chemiosmosis, underscoring their critical role in maintaining cellular metabolism.

Related terms

ATP: Adenosine triphosphate (ATP) is a molecule that carries energy within cells and is produced during cellular respiration.

Glycolysis: Glycolysis is the first step of cellular respiration, where glucose is broken down into pyruvate, producing a small amount of ATP and NADH.

Mitochondria: Mitochondria are the organelles in eukaryotic cells where the majority of ATP production occurs during cellular respiration.