Question

How does the redox potential relate to the affinity a molecule has for electrons? How does the redox potential explain the pathway electrons take through the electron transport chain?

What are the 3 conformations of the ATP synthase? How is ATP produced?

Answer 1

Reduction means a receiving or gaining of electrons, such as when an antioxidant donates an electron to a free radical. The free radical is reduced and the antioxidant is oxidized. The antioxidant is said to be the “reducing agent”; it reduces the free radical. Whereas the free radical is called the “oxidizing agent”; it oxidizes the antioxidant. The redox potential is a characteristic of the chemical species to undergo an oxidation-reduction reaction. It is stored energy that has the ability to do work and is measured in volts. Each species has its own reduction potential; the more positive potential, the greater the species' affinity for electrons and tendency to be reduced.

Our cells are excellent at harvesting energy from glucose. When glucose is broken down in the presence of oxygen, it converted into six carbon dioxide molecules and six water molecules. Energy contained in the bonds of glucose is released and is captured to keep the metabolism of the cell running. In electron transport chain, electrons from glucose are transferred to small molecules known as electron carriers. The electron carriers take the electrons to a group of proteins in the inner membrane of the mitochondrion, called the electron transport chain. when electron passes through the electron transport chain, the energy it releases is used to pump protons out of the matrix of the mitochondrion, forming an electrochemical gradient. When the start superscript, plus, end superscript flow back down their gradient, they pass through an enzyme called ATP synthase, driving synthesis of ATP.

In the first step of 3 conformations of the ATP synthase, the asymmetric γ subunit rotates 120° clockwise driving conformational changes in the three catalytic sites that alter their affinities for substrates and product. In this illustration, the catalytic sites remain stationary. In step 2, ATP forms spontaneously from tightly bound ADP and Pi. and then is carried to the other partial channel by rotation of the c12 complex. The c subunits are anchored to γ, the rotation of c12 relative to the a subunit in F0 will drive the rotation of γ relative to the hexamer.

Chemically, ATP is known as adenosine triphosphate. ATP is a usable form of energy for cells. ATP is created through a complex enzyme-driven process. There are a couple of ways this works in cells:

-glycolysis, in which glucose is broken up into two subunits, called pyruvate, which creates two units of ATP per molecule of glucose. This happens in the cytoplasm, in both animal and plant cells.

-respiration, in which pyruvate is combined with oxygen to form carbon dioxide and water, which creates a lot of ATP per unit of pyruvate. This happens in the mitochondrion, which likewise exists in both animals and plants.

-light-dependent photosynthesis, in which electrons are cycled around photosynthetic pigments after being used around by mid-high-energy light particles, which filter through an electron pump that makes ATP. This happens in chloroplasts, and as such only occurs in plants.