Help In all Draw the structure of mitochondria and explain what process occurs i
ID: 57737 • Letter: H
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Help In all Draw the structure of mitochondria and explain what process occurs in each of these compartments Explain how NAD+ and FAD carry electrons Explain how you separated mitochondria in your lab. Explain chemiosmosis Describe the components of the electron transport chain and their function Where do NADH and FADH2 enter the chain? Explain the role of ubiquinone in mitochondrial electron transport Where is cytochrome C located in the mitochondrial membrane? To which complex does it transfer the electrons? What are the four main components of complex 4 or cytochrome c oxidase? Which components of cytochromec oxidase transfer the electrons to oxygen? What is the purpose of using a positive control for the assay? At what wavelength did reduced and oxidized cytochrome c absorb light? What reagent did you use to reduce cytochrome c? What the ratio is of reduced Cyt C / oxidized cyt C before the measurement of enzyme activity? What happened to the absorption at 550nm after theExplanation / Answer
* Both NAD and FAD can change their oxidation state by binding electrons. The reduction is a nucleophilic addition.
The ring strucutre of NIcotinamide in NAD exists in a resonance structure/with alternative double bonds. It can accept two electrons, one attach to one of the carbons and another one to the Nitrogen that is linked to Ribose. The compound removes two hydrogen atoms from a reactant in the form of hydride ion and a proton. From the hydride electron pair, one electron is transferred to positively charged nitrogen that bins to the ribose sugar. The second one, the hydrogen atom, is transferred to C4 carbon. Due to NAD can carry two electrons, and one proton.
Similar mechanism operates with FAD and FADH2 also. However, FAD carries two protons and two electrons. The reduction involves formation of hydride ion, radical formation, and hydride loss.
* Electron transport chain components:
a. NADH: It provides electrons to the coenzymes in the chain. It transfers two electrons at a time in the form of hydride.
b. FAD/FMN: They can accept and donate either one or two electrons at a time. They are mediators between two electron acceptors and one electron acceptors.
c. Coenzyme Q: It is a ubiquinone, which can accept either one or two electrons at a time. It has redox potential of 0.060 V
d. Cytochromes: They contain heme prosthetic groups, and are one electron carriers
e. Iron-sulfer proteins: Several iron sulfer proteins are present in ETC. They participate in one electron transfers through their ferrous and ferric oxidation states
* Mitochondria are isolated by differential centrifugation. The cells are initially lysed by keeping them in a hypotonic solution. Potassium cyanide is used to stop flow of electrons to electron transport chain. Mitochondria isolation buffer is used for differential centrifugation once cells are lyzed. The buffer typically contains 10mM HEPES at pH 7.5, 200mM D-Mannitol, 70mM sucrose, 1 mM EGTA at pH 8.0. After isolation, 195 mM sucrose is used to preserve the mitochondria in isoosmotic conditions. MItochondria isolation buffer generally contain.
* Chemiosmosis: It is the process of movement of protons across the membranes. It is diffusion that happens over plasma membrane. However, along with the concentration, electrical charge on the molecules is also considered. Pumping of protons through special channels from the inner mitochondria to outer mitochondrial membrane compartment establishes a proton gradient. once the gradient is established, the protons diffuse back down the gradient through transport protein called ATP synthase.
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