Cellular respiration

Definition

Cellular respiration is the metabolic process through which cells convert nutrients into energy, primarily in the form of adenosine triphosphate (ATP), by breaking down glucose and other organic molecules. This process takes place in different cellular compartments and involves various organelles that play specific roles, highlighting the complexity of energy production in both simple and complex organisms.

5 Must Know Facts For Your Next Test

1. Cellular respiration can be aerobic, requiring oxygen, or anaerobic, occurring in the absence of oxygen, with different end products.
2. In eukaryotic cells, glycolysis occurs in the cytoplasm, while the Krebs cycle and electron transport chain take place in the mitochondria.
3. During cellular respiration, glucose is fully oxidized to carbon dioxide and water, releasing energy stored in its chemical bonds.
4. The efficiency of aerobic cellular respiration can yield up to 36-38 molecules of ATP per molecule of glucose, while anaerobic processes yield only 2 ATP.
5. Fermentation is an alternative pathway for energy production when oxygen is scarce, allowing cells to continue producing ATP through glycolysis.

Review Questions

• How do the structures of prokaryotic and eukaryotic cells influence their methods of cellular respiration?
  • Prokaryotic cells typically carry out cellular respiration across their cell membranes since they lack membrane-bound organelles. In contrast, eukaryotic cells utilize specialized organelles like mitochondria for aerobic respiration. This distinction allows eukaryotic cells to efficiently produce more ATP via oxidative phosphorylation compared to prokaryotes, which may rely on simpler processes like fermentation or anaerobic respiration due to their structural limitations.
• Analyze how different organelles contribute to the process of cellular respiration in eukaryotic cells.
  • In eukaryotic cells, glycolysis occurs in the cytoplasm, breaking down glucose into pyruvate and generating a small amount of ATP. The pyruvate then enters the mitochondria where it is further processed through the Krebs cycle, producing electron carriers like NADH and FADH2. These carriers feed into the electron transport chain in the inner mitochondrial membrane, leading to the majority of ATP production. Each organelle plays a crucial role, ensuring that energy is efficiently extracted from nutrients.
• Evaluate the impact of anaerobic respiration on energy production and cellular processes when oxygen is limited.
  • Anaerobic respiration allows organisms to continue producing ATP under low-oxygen conditions but is far less efficient than aerobic respiration. For example, in muscle cells during strenuous exercise, lactic acid fermentation occurs, generating only 2 ATP from glucose instead of up to 38 with oxygen present. This limited energy production can lead to fatigue and muscle cramps. Understanding this impact highlights how different organisms adapt their metabolism to survive varying environmental conditions while still managing their energy needs.

Related terms

ATP:

Adenosine triphosphate (ATP) is the primary energy carrier in cells, providing the energy needed for many biochemical reactions.

Mitochondria: Mitochondria are known as the powerhouse of the cell, where the majority of ATP is produced through aerobic respiration.

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