Question

explain how oxygen is used to create a concentration gradient in the mitochondria.

raw a picture of where the hydrogen ions (H+ are, where they go, and why there movement is important).

What is the role of oxygen in this process?

Answer 1

If there's one thing that mitochondria thrive on, its oxygen. All of it is consumed by cytochrome oxidase, the last enzyme in the electron transport chain which drives ATP production. If cells relied on diffusion alone to supply them with their oxygen needs, then there would not be enough to keep up with demand. So oxygen carrying molecules, such as haemoglobin and myoglobin, evolved to transport oxygen to where it is needed.

Although the mechanism by which energy is harvested by the respiratory chain differs from that in other catabolic reactions, the principle is the same. The energetically favorable reaction H2 + ½O2 → H2O is made to occur in many small steps, so that most of the energy released can be stored instead of being lost to the environment as heat. The hydrogen atoms are first separated into protons and electrons. The electrons pass through a series of electron carriers in the inner mitochondrial membrane. At several steps along the way, protons and electrons are transiently recombined. But only when the electrons reach the end of the electron-transport chain are the protons returned permanently, when they are used to neutralize the negative charges created by the final addition of the electrons to the oxygen molecule.

process of electron transport begins when the hydride ion is removed from NADH (to regenerate NAD+) and is converted into a proton and two electrons (H-→ H+ + 2e -). The two electrons are passed to the first of the more than 15 different electron carriers in the respiratory chain. The electrons start with very high energy and gradually lose it as they pass along the chain. For the most part, the electrons pass from one metal ion to another, each of these ions being tightly bound to a protein molecule that alters the electron affinity of the metal ion (discussed in detail later). Most of the proteins involved are grouped into three large respiratory enzyme complexes, each containing transmembrane proteins that hold the complex firmly in the inner mitochondrial membrane. Each complex in the chain has a greater affinity for electrons than its predecessor, and electrons pass sequentially from one complex to another until they are finally transferred to oxygen, which has the greatest affinity of all for electrons.