key term - Electron carriers

Definition

Electron carriers are molecules that transport electrons during cellular respiration and photosynthesis, playing a critical role in energy production. These carriers facilitate the transfer of electrons from one molecule to another, allowing energy to be released in a controlled manner. They are essential for generating a proton gradient that drives ATP synthesis through oxidative phosphorylation.

5 Must Know Facts For Your Next Test

1. Electron carriers like NADH and FADH2 are generated during metabolic processes such as glycolysis and the citric acid cycle.
2. These carriers donate their electrons to the electron transport chain, where the energy released is used to pump protons across the inner mitochondrial membrane.
3. The resulting proton gradient drives ATP synthase to produce ATP during oxidative phosphorylation.
4. Electron carriers can also play roles in photosynthesis by transferring electrons from light-excited chlorophyll to other molecules in the thylakoid membrane.
5. The efficiency of electron carriers in transferring electrons is crucial for maximizing ATP yield during cellular respiration.

Review Questions

• How do electron carriers contribute to the process of ATP production?
  • Electron carriers contribute to ATP production by transporting high-energy electrons from metabolic processes like glycolysis and the citric acid cycle to the electron transport chain. When these electrons move through the chain, they release energy, which is used to pump protons into the intermembrane space. This creates a proton gradient that drives ATP synthase, resulting in the conversion of ADP to ATP through oxidative phosphorylation.
• Evaluate the roles of NADH and FADH2 in cellular respiration and compare their contributions to ATP synthesis.
  • NADH and FADH2 both act as crucial electron carriers in cellular respiration but differ in their contributions to ATP synthesis. NADH typically enters the electron transport chain at Complex I, contributing more significantly to the proton gradient and yielding about 2.5 ATP per molecule. In contrast, FADH2 enters at Complex II, resulting in fewer protons being pumped across the membrane and yielding approximately 1.5 ATP per molecule. This difference highlights their distinct roles in energy metabolism.
• Analyze how malfunctioning electron carriers can impact overall cellular energy production and lead to disease.
  • Malfunctioning electron carriers can severely disrupt cellular energy production by impairing the transfer of electrons within the electron transport chain. This can lead to decreased ATP synthesis and increased production of reactive oxygen species due to incomplete electron transfer. Conditions such as mitochondrial diseases may arise from such dysfunctions, resulting in symptoms related to energy deficiency, particularly in high-energy demanding tissues like muscles and the brain. Ultimately, these issues can compromise overall metabolic health and lead to various diseases.

Related terms

NADH:

Nicotinamide adenine dinucleotide (NADH) is a key electron carrier that carries high-energy electrons to the electron transport chain, contributing to ATP production.

FADH2:

Flavin adenine dinucleotide (FADH2) is another important electron carrier that donates electrons to the electron transport chain, playing a significant role in energy metabolism.

ubiquinone:

Ubiquinone, also known as coenzyme Q, is a lipid-soluble electron carrier that transfers electrons between various protein complexes in the electron transport chain.