How do animal cells get energy?

SouravAugust 21, 2024

Answer

Animal cells obtain energy primarily through the process of cellular respiration, which takes place in the mitochondria, the cell’s energy powerhouse. Here’s a detailed look at how animal cells generate energy:

1. Cellular Respiration

Cellular respiration is the process through which animal cells convert nutrients into adenosine triphosphate (ATP), the primary energy currency of the cell. It involves several stages:

• Glycolysis:
  • Location: Cytoplasm
  • Process: Glucose, a six-carbon sugar, is broken down into two molecules of pyruvate, producing a small amount of ATP and NADH (a carrier of electrons).
• Pyruvate Oxidation:
  • Location: Mitochondrial matrix
  • Process: Each pyruvate is converted into acetyl-CoA, which then enters the Krebs cycle. This step also produces NADH and FADH2.
• Krebs Cycle (Citric Acid Cycle):
  • Location: Mitochondrial matrix
  • Process: Acetyl-CoA is oxidized, generating NADH and FADH2, and releasing carbon dioxide as a byproduct. This cycle also produces a small amount of ATP.
• Oxidative Phosphorylation:
  • Location: Inner mitochondrial membrane
  • Process: NADH and FADH2 donate electrons to the electron transport chain (ETC). As electrons move through the chain, protons are pumped across the mitochondrial membrane, creating a proton gradient. The flow of protons back through ATP synthase drives the production of ATP. Oxygen acts as the final electron acceptor, forming water.

2. Anaerobic Respiration

In the absence of oxygen, animal cells can perform anaerobic respiration (or fermentation) to produce ATP:

• Lactic Acid Fermentation:
  • Location: Cytoplasm
  • Process: Pyruvate from glycolysis is converted into lactic acid. This process regenerates NAD+ but yields less ATP compared to aerobic respiration. Lactic acid can accumulate in muscles during intense exercise.

3. Additional Sources

• Fatty Acids and Amino Acids:
  • Fatty Acids: Can be broken down in a process called β-oxidation to produce acetyl-CoA, which enters the Krebs cycle.
  • Amino Acids: Can be deaminated and converted into various intermediates that enter the Krebs cycle.