elektroninsiirtosarja

An electron transport chain, or elektroninsiirtosarja in Finnish, is a series of protein complexes and small organic molecules that shuttle electrons from one molecule to another in a redox reaction. These chains are crucial for cellular respiration and photosynthesis, playing a vital role in energy production.

In cellular respiration, the electron transport chain is located in the inner mitochondrial membrane. Here, electrons are passed from molecules like NADH and FADH2 to a series of protein complexes. As electrons move through the chain, energy is released and used to pump protons from the mitochondrial matrix into the intermembrane space. This creates an electrochemical gradient, which then drives the synthesis of ATP, the main energy currency of the cell, through a process called chemiosmosis.

In photosynthesis, electron transport chains are found in the thylakoid membranes of chloroplasts. They are involved in the light-dependent reactions, where light energy is captured and converted into chemical energy in the form of ATP and NADPH. Electrons are excited by light and then passed along a series of carriers, ultimately leading to the reduction of NADP+ to NADPH and the production of ATP.

The specific components and arrangement of electron transport chains can vary depending on the organism and the metabolic pathway. However, the fundamental principle of sequential electron transfer and energy coupling remains consistent, highlighting their importance in the flow of energy within biological systems.