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Pre Medical exams, AIIMS AND NEET : ELECTRON TRANSPORT SYSTEM (ETS) AND OXIDATIVE PHOSPHORYLATION
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Details of electron transport system and oxidative phosphorylation, an analytical approach.

Dr Praveen Kumar Agrawal is teaching live on Unacademy Plus

Dr Praveen Kumar Agrawal
Ex - Faculty, Allen Kota, 22 Yrs Experience. Author - 17 books Known for best explanation Youtube : biology by pkagrawal

U
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hamare module me to 5 complex diye h sir ........ explain plz
explain by new nceart
ME
I wish you were the professor of our college 😕😕.you are so great
mobile electron carriers means
sir!! you are brilliant amazing awesome ✌️ single teacher who gave me this kind of rock solid concepts for ETS.
  1. Lesson 7 Electron Transport System (ETS) (Oxidative Phosphorylation) (Chemiosmosis) Dr. P. K. Agrawal M.Sc., Ph.D., CSIR-NET (JRF), SRF, GATE, FIAZ Youtube Channel with over 1 million views 20 Years of Pre-medical teaching experience Ex- Faculty, Allen Career Institute, Kota Visit following link to follow my profile https://unacademy.com/user/biologybypkagrawal-6909


  2. Need of ETS . By the end of Krebs' cycle, the oxidation of glucose is completed as at has given out 6CO2 molecules. But the energy obtained till now is very less (2 ATPs in glycolysis and 2 in each Krebs cycle). The full amount of energy is still to be obtained. . The reduced coenzymes NADHH and FADH2, which are formed in glycolysis and Krebs' cycle, contain a huge amount of energy. This energy can be released and utilized to form ATP on their oxidation. This oxidation takes place through a series of electron transport, called ETS. . The oxidation of NADH+H and FADH2 occurs as shown in following equations- NADH+H xdationNAD 2H 2e oxidation FAD + 2H+ + 2e FADH2 The electrons and protons generated in these reactions, pass through a series of career proteins and finally generate a water molecule and large amount of energy, which is stored in the form of ATPs


  3. Basic concept of ETS and arrangement of component:s . The H ions (released from the above reactions), when passed across the mitochondrial membrane from cytoplasmic side (C-side) to matrix side (M-side), release a large amount of energy, which is utilized by F1 particles to form ATP. This ATP formation in mitochondria during aerobic respiration is termed as oxidative phosphorylation. . The electrons released from the oxidation of these coenzymes, are passed through a complex series of electron carriers ( FMN, UQ, cytochromes and FeS proteins). These carriers are located inside the inner mitochondrial membrane. Various components of ETS are arranged one after the other, in order of their in creasing redox potential. This order is as follows NADH+H+, Most-ve potential FMN, Fe-S, UQ, Cyt-b, Fe-S, UQ, Cyt-c , Cyt-c, Cyt-a, Cyt-a3 , 02 Most +ve potential The components are arranged in the form of four complexes as shown in the figure on the next screen.


  4. C side (Space b/w i nnerand outer membranes M side Inne rMitochondrial Membrane (IMM) FMN -NADH + H Complex I Fe-S Complex II US Cyt b 1. Complex I (NADH-Q-reductase) (15 subunits including FMN and FeS Proteins) Fe-S Complex IlI Cyt cl 2. Complex II (Succinate-Q-reductase) (2 polypeptides with FAD and FeS proteins) Cyt c 3. Complex III (QH2 cytochrome-c-reductase) (Cyt-b, Cyt-c1 and FeS proteins) Cyt a 4. Complex IV (Cytochrome-c-oxidase) (many polypeptides with Cyt-a and-a3 and two Cu) Complex IV Cyt a3 (C) P KAgrawal


  5. Oxydative phosphorylation and production of ATP (Chemiosmosis) C-side +-- M-side The protons, (H+), released from reduced coenzymes are transported across the membrane from matrix to perimitochondrialspace, (M to C-side) ADP iP . This transport of H+, across the membrane, causes a pH difference 2 H 2 H and a membrane potential to setup (due to unequal charge distribution). These developments in turn creates a proton motive force, which induce these protons to return back to matrix from peri-mitochondrialspace (C to M-side) I The inner mitochondrial membrane is impermeable for this back outer transfer of protons ATPase ATP Inner membrane membrane space . The return of H+from C to M-side, can occur only through F F1 particles are in fact a multiple polypeptide complex (Complex V). It consists of two major components Fo and Fa is the head portion and it contains ATPase (ATP synthase enzyme). When H+ ions, move from C to M-side particles. This is chemiosmosis (P. Mitchel) 1 through these particles, the ATPase gets activated and it catalyzes the synthesis of ATP by joining the ADP and iP (inorganic phosphate)


  6. Highly ve Redox Potential Basic Scheme and Concept of Electron Transport System (ETS) 2e 2e 2H 2H 2e AT P 2e Highly +ve Redox Potential 2e AT P 2H AT P Oxygen (C) P K Agrawal


  7. Terminal oxidation In electron transport system, the electrons and protons released from reduced coenzymes, pass through several carriers, which are arranged in a chain. These electrons and protons are finally accepted by oxygen molecule to form water . This is the last step of ETS. Hence this oxidation reaction is known as terminal oxidation (So, in entire process of respiration, oxygen is used only in the last step) 202 2H 2e H2o


  8. Significance ETS helps in the complete oxidation of reduced coenzymes and harnessing their full energy. ETS helps in oxidative phosphorylation which gives rise to high amount of energy i.e., 3 ATPs per NADH+H+ ETS helps in the unloading of reduced coenzymes thereby help in continuing Krebs cycle and glycolysis


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