Electron transport

Definition

Electron transport refers to the series of reactions in which electrons are transferred through a chain of proteins embedded in the inner mitochondrial membrane or thylakoid membrane of chloroplasts. This process is essential for energy production in both cellular respiration and photosynthesis, as it facilitates the generation of ATP through chemiosmosis, where the movement of protons across a membrane is coupled with the synthesis of ATP.

5 Must Know Facts For Your Next Test

1. The electron transport chain is composed of four main protein complexes that facilitate electron transfer and create a proton gradient across the membrane.
2. In plants, the electron transport chain occurs in the thylakoid membranes of chloroplasts during photosynthesis, where light energy is used to excite electrons.
3. During cellular respiration, electrons are donated to the electron transport chain primarily by NADH and FADH2, which are generated during earlier metabolic processes.
4. The final electron acceptor in aerobic respiration is oxygen, which combines with electrons and protons to form water, a crucial step for maintaining the flow of electrons.
5. The efficiency of ATP production through electron transport can be influenced by factors such as temperature, pH, and the availability of substrates.

Review Questions

• How does electron transport contribute to ATP production in both cellular respiration and photosynthesis?
  • Electron transport plays a critical role in ATP production by establishing a proton gradient across membranes in mitochondria and chloroplasts. In cellular respiration, as electrons move through the electron transport chain, protons are pumped into the intermembrane space, creating a gradient. This gradient drives protons back through ATP synthase, producing ATP. Similarly, in photosynthesis, light energy excites electrons that travel through the chain, facilitating ATP synthesis via chemiosmosis.
• Discuss the importance of oxygen in the electron transport process during aerobic respiration.
  • Oxygen is vital in aerobic respiration as it acts as the final electron acceptor at the end of the electron transport chain. When oxygen accepts electrons and combines with protons, it forms water, preventing backup in the electron flow. This reaction not only sustains the efficiency of ATP production but also allows continued operation of the entire cellular respiration process. Without oxygen, cells would resort to less efficient anaerobic pathways.
• Evaluate how disruptions in electron transport can affect plant health and energy production.
  • Disruptions in electron transport can significantly impact plant health and energy production by hindering ATP synthesis. If electron transfer is blocked or inefficient due to factors such as toxins or environmental stressors, plants may experience reduced energy levels needed for growth and development. This deficiency can lead to impaired photosynthesis, affecting overall plant metabolism and potentially leading to lower yields and compromised resistance to disease.

Related terms

ATP synthase: An enzyme that creates ATP from ADP and inorganic phosphate during the process of chemiosmosis, utilizing the proton gradient established by electron transport.

Chemiosmosis: The movement of protons across a membrane, driving the synthesis of ATP as protons flow back into the mitochondrial matrix or chloroplast stroma.

Oxidative phosphorylation: The final stage of cellular respiration, where ATP is generated from ADP and inorganic phosphate using energy derived from the electron transport chain.