Ferredoxins are small iron-sulfur proteins that play a crucial role in various biological processes. They are involved in electron transfer reactions, facilitating the movement of electrons between different molecules in cells. This function is essential for processes such as photosynthesis and cellular respiration. These proteins are found in a wide range of organisms, including plants, bacteria, and archaea. Their structure typically includes clusters of iron and sulfur atoms, which enable them to accept and donate electrons efficiently. This makes ferredoxins vital for energy production and metabolic pathways in living organisms.