Biology Times (^) March 19
The total number of co-enzymes formed in mitochondria from two pyruvates derived from one glucose
molecule is 8 NADH(+H+) and 2 FADH 2 , two molecules of GTP/ATP are also produced. The products
of glycolysis available per glucose are 2 NADH(+H+) and 2 ATP, therefore the total yield of co-enzymes
formed from one molecule of glucose are 10 NADH(+H+) and 2 FADH 2. There is also a gain of 4 ATP
molecules.
Significance of Kreb’s cycle
m Kreb’s cycle yields one ATP per pyruvic acid via substrate level phosphorylation.
m Kreb’s cycle forms the central pool of organic acids which are linked with other pathways like the synthesis
of amino acids, fatty acids etc.m It provides 5 NADH 2 and one FADH 2 for terminal oxidation.Step IV: Terminal Oxidation, Electron Transport System (ETS) and Oxidative Phosphorylation
Terminal oxidation is the oxidation found in aerobic respiration that occurs towards the end of process
and involves the passage of both electrons and protons from reduced co-enzymes to oxygen. Terminal
oxidation consists of 2 processes, Electron transport and oxidative phosphorylation.
The electron transport system (ETS) is a series of hydrogen and electron carriers embedded in the inner
membrane of a mitochondrion. At the end of citric acid cycle glucose molecule is completely oxidised.
But the energy is not released unless NADH 2 and FADH 2 are oxidised through the electron transport
system. The metabolic pathway through which the electron passes from one carrier to another is called the
electron transport chain ( ETC).1.
- m It occurs in inner membrane (cristae) – Energy transducing membrane
m It begins with oxidation of NADH 2 (Reduced Co-enzyme) & FADH 2 (Reduced prosthetic Co-enzyme)- Both are reduced ‘H’ oxidisers.
m It requires 5 complexes (All are integral proteins/ enzymes): COMPLEX-I, II, III, IV, V and 2 mobile
carriers: UQ (internal membrane) Cyt.c (external membrane)
- Both are reduced ‘H’ oxidisers.