What is the difference between ubiquinones and cytochromes

The free energy released by the spontaneous transfer of electrons from the NADH-Q reductase complex to ubiquinone is used for a very important purpose. As we will see later, this proton gradient ultimately provides the energy needed to generate ATP! Ubiquinone is an electron carrier only ; it is not a proton pump. As the electron is spontaneously transferred from one group to another in the protein complex, free energy is released.

This free energy is used to pump protons from the matrix, across the inner mitochondrial membrane through cytochrome reductase , and into the intermembrane space. Hence, the proton gradient is increased further. Cytochrome oxidase also has an important, unique feature that is necessary because it transfers its electrons to O 2. O 2 has a difficult time picking up one extra electron to form the free-radical species O 2 - ; however, once O 2 has accepted one electron it becomes very reactive, and can easily accept more electrons, or participate in other chemical reactions.

A free radical is a group that contains an unpaired electron. Free radicals are extremely reactive. Many of the chemical reactions that the free radical O 2 - could participate in, such as the destruction of fatty acids that make up membranes, would be very harmful to the body. Cytochrome oxidase acts as an enzyme to help add the first electron to O 2. Overview and Key Difference 2. What are Ubiquinones 3. What are Cytochromes 4. Similarities Between Ubiquinones and Cytochromes 5. Ubiquinones Coenzyme Q are small lipid-soluble organic molecules found in the inner mitochondrial membrane.

Howver, they are not protein molecules, and they do not contain heme groups, instead they work as electron carriers in the electron transport chain. Ubiquinone accepts electrons from NADH reductase and passes to cytochrome for further transportation. Ubiquinones are lipid soluble and hydrophobic. Hence, they can freely diffuse within the membrane and act as efficient electron carriers. When ubiquinone accepts one electron, it becomes semiquinone, and when accepts two electrons it becomes ubiquinol.

Cytochromes are a protein complex that acts as an electron carrier in electron transport chain. Therefore, they are loosely associated with the inner membrane of the mitochondria. Moreover, they are small heme proteins. Cytochromes serve as extreme important electron carriers since they facilitate the handover of electrons to a final electron acceptor O 2 to complete respiration. Moreover, there are three main cytochromes namely cytochrome reductase, cytochrome c and cytochrome oxidase.

Cytochrome reductase receives electrons from ubiquinone and transfers to cytochrome c. Thereafter, cytochrome c transfers an electron to cytochrome oxidase. Finally, cytochrome oxidase passes electrons to O 2 the final electron acceptor.

When electrons travel through electron carriers, a proton gradient will create, and it will help for the ATP production. Ubiquinones and Cytochromes are two efficient and important electron carriers in the process of respiration.

Ubiquinones are lipid soluble, hydrophobic small organic molecules. On the other hand, cytochromes are heme-containing protein molecules.