What is the relationship between chemiosmosis and ATP sythesis? | Yahoo Answers
ATP synthase (also known as FoF1-ATP synthase) is a multisubunit integral membrane protein that produce ATP from ADP and P i using the energy of. Lesser degrees of similarity, and more distant evolutionary relationships, exist with Archaeal ATP synthases and with vacuolar membrane. Chemiosmosis: In oxidative phosphorylation, the hydrogen ion gradient formed by the electron transport chain is used by ATP synthase to form ATP.
What creates the proton gradient across the membrane?
Chemiosmosis — this is really important! We have seen how ATP synthase acts like a proton-powered turbine, and uses the energy released from the down-gradient flow of protons to synthesize ATP. The process of pumping protons across the membrane to generate the proton gradient is called chemiosmosis. Chemiosmosis is driven by the flow of electrons down the electron transport chain, a series of protein complexes in the membrane that forms an electron bucket brigade.
Each of these protein complexes accepts and passes on electrons down the chain, and pumps a proton across the membrane for each electron it passes on. Ultimately, the last complex in the electron transport chain passes the electrons to molecular oxygen O2 to make water, in the case of aerobic respiration.
We define respiration as the passage of electrons down the electron transport chain. We breathe respire oxygen because oxygen is the terminal electron acceptor, the end of the line for our mitochondrial electron transport chain. The video below shows the details of the electron transfer reactions, and how they are coupled to pumping protons across the membrane.
This is a form of active transport, because the electron transfers release free energy that is used to pump protons against their concentration gradient. Watch this video to understand how the ETC creates a proton gradient My lecture explanation: Many bacteria can use other terminal electron acceptors when oxygen is unavailable; we say that they carry on anaerobic respiration, when the electron transport chain functions in the absence of oxygen, using an alternative terminal electron acceptor.
Respiration, chemiosmosis and oxidative phosphorylation
A molecule that loses electrons is oxidized; a molecule that gains electrons is reduced. Different molecules have different tendencies to gain or lose electrons, called the redox potential. A redox reaction between a pair of molecules with a large difference in redox potential results in a large release of free energy.
In aqueous environments, the transferred electrons pick up protons. Living cells are the original hydrogen fuel cells.
Chemiosmosis - Wikipedia
Cellular energy metabolism features a series of redox reactions. NADH is a high-energy molecule. The oxidation of NADH: The membrane electron transport chain and chemiosmosis is a strategy for cells to maximize the amount of ATP they can make from the large amounts of free energy available in NADH. The electron transport chain subdivides the oxidation of NADH by O2 to a series of lower energy redox reactions, which are used to pump protons across the membrane.
Anaerobic respiration in bacteria The amount of energy released by these redox reactions, and thus the amount of energy available for ATP synthesis, depends on the redox potential of the terminal electron acceptor. Oxygen O2 has the greatest redox potential, and thus aerobic respiration results in the most ATP synthesized. Bacteria and Archaea can use other terminal electron acceptors with lower redox potential when oxygen is not available.
What is the relationship between chemiosmosis and ATP sythesis?
More broadly, chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work. For instance, chemiosmosis is also involved in the light reactions of photosynthesis.
What would happen to the energy stored in the proton gradient if it weren't used to synthesize ATP or do other cellular work? It would be released as heat, and interestingly enough, some types of cells deliberately use the proton gradient for heat generation rather than ATP synthesis.
This might seem wasteful, but it's an important strategy for animals that need to keep warm. For instance, hibernating mammals such as bears have specialized cells known as brown fat cells.
In the brown fat cells, uncoupling proteins are produced and inserted into the inner mitochondrial membrane. These proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through ATP synthase. By providing an alternate route for protons to flow back into the matrix, the uncoupling proteins allow the energy of the gradient to be dissipated as heat.
If you look in different books, or ask different professors, you'll probably get slightly different answers. Diffusion force caused by a concentration gradient - all particles tend to diffuse from higher concentration to lower. Anions diffuse spontaneously in the opposite direction. These two gradients taken together can be expressed as an electrochemical gradient.
Lipid bilayers of biological membraneshowever, are barriers for ions. This is why energy can be stored as a combination of these two gradients across the membrane. Only special membrane proteins like ion channels can sometimes allow ions to move across the membrane see also: In chemiosmotic theory transmembrane ATP synthases are very important.
They convert energy of spontaneous flow of protons through them into chemical energy of ATP bonds. Hence researchers created the term proton-motive force PMFderived from the electrochemical gradient mentioned earlier.Electron transport chain and ATP synthesis