GTP is converted to GDP with the simultaneous synthesis of ATP from ADP. Also there are three points in the cycle where NAD + is reduced to NADH + H + and one point where FAD + is reduced to FADH . The continued oxidation of acetyl CoA via the TCA cycle requires the continued replenishment of oxaloacetic acid, the first member of the cycle. In addition it also requires regeneration of NAD + and FAD + from NADH and FADH respectively.
The summary equation for this phase of respiration may be written as follows: FADH We have till now seen that glucose has been broken down to release CO and eight molecules of NADH + H + ; two of FADH have been synthesised besides just two molecules of ATP in TCA cycle. You may be wondering why we have been discussing respiration at all – neither O has come into the picture nor the promised large number of ATP has yet been synthesised. Also what is the role of the NADH + H + and FADH that is synthesised? Let us now understand the role of O in respiration and how ATP is synthesised.
. . Electron Transport System (ETS) and Oxidative Phosphorylation The following steps in the respiratory process are to release and utilise the energy stored in NADH+H + and FADH . This is accomplished when they are oxidised through the electron transport system and the electrons are passed on to O resulting in the formation of H O.
The metabolic pathway through which the electron passes from one carrier to another, is called the electron transport system electron transport system electron transport system electron transport system electron transport system (ETS) (Figure . ) and it is present in the inner mitochondrial membrane. Electrons from NADH Figure . The Citric acid cycle Pyruvate Acetyl coenzyme A (2C) Citric acid Oxaloacetic acid (4C) CO CO CITRIC ACID CYCLE α -ketoglutaric acid (5C) GDP GTP Succinic acid (4C) Malic acid (4C) FADH FAD + CoA CO