The molecule of pyruvic acid which is made in glycolysis enters in kerbs cycle(if oxygen is present)
Krebs cycle start with aetyl coA so firstly pyruvic acid changed in acetyl coA. For this TPP co-enzyme and Mg++ are important. In this process oxidation and decarboxilation held together so this process called oxidation decarboxilation. For this process pyruvic dehydrogenase complex is important. This complex is group of three enzymes.These enzymes are-
1.Pyruvate decarboxynilase
2Lipoate reductase trans acetylase
3.De hydrolipoate dehydrogenase
Energy yieldduring oxidative decarboxilation-
2 pyruvic acid+2NAD-2 acetyl coA+ 2NADH2
2NADH2- 6ATP
For first step of aerobic respiration click here-GLYCOLYSIS
KREBS CYCLE/TCA CYCLE/CITRIC ACID CYCLE
Krebs cycle was discovered by Hans Krebs.It occur inside mitochondria.It is a amphibolic path way because it is a comon path wat for protien,lipids catabolism. Acetyl coA functions as sbstrate entrant for Kreb cycle.This cycle complates in 10 steps.These are-
1.Condensation-Acetyl coA combines with oxalo acetate in the presence of citrate synthetase to form citric acid.
Acetyl coA+OAA→citric acid+CoA-Sh
2.Dehydration-Citrate forming Aconitic acid with releasing of water molecule in the presence of aconitase.
Citrate→cis aconitic acid
3.Hydration-cis aconitate is converted into isocitrate with the addition of water in the presence of aconitase.
Cis aconitate+water molecule→Isocitrate
4.Dehydrogenation-Isocitrate is dehydrogenated to oxalosuccinate in the presence of enzyme isocitrate dehydrogenase and Mn++.NADH2 is produced.
isocitrate+NAD+→oxalosuccinate+NADH2
5.Decarboxilation-Oxalosuccinate is decarboxylated to from α-ketoglutarate through enzyme decarboxylase.
Oxalosuccinate→ α-ketoglutarate
6.Dehydrogenation and Decarboxylation- α-ketoglutarate is both dehydrogenated and decarboxylated by an enzyme complex α-ketoglutarate dehydrogenase.the enzyme complex contains TPP and lipoic acid.The product combines with coA to from succinyl CoA.
α-ketoglutarate+CoA+NAD→SuccinylCoA+NADH+H+
7.Formation of ATP/GTP-Succinyl CoA is acted upon by enzyme succinyl thiokinase to form succinate.The reaction release sufficient energy to form ATP or GTP.
8.Dehydrogenation-Succinate undergoes dehydrogenation to form fumarate with the help of a dehydrogenase.FADH2 is produced.
9.Hydration-A molecule of water gets added to fumerate to form malate. The enzyme is called fumarase.
10.Dehydrogenation-Malate is Dehydrogenated or oxidised through the energy of malate dehydrogenase to produce oxaloacetate. Hydrogen is accepted by NADP+NAD+
2.Isocitric aid to oxallosuccinic acid(NAD) 3ATP
3. α-Ketogutric acid to succinyl cova(NAD) 3ATP
4.Succinic acid to fumaric acid(FAD) 2ATP
5.Malic acid to OAA(NAD) 3ATP
6.Succinyl coA to succinic acid 1ATP
=15ATP
Total ATP produced during
complate oxidation of Pyruvic acid =2x15=30ATP
And during glycolysis=8ATP
TOTAL ATP=38ATP
Krebs cycle start with aetyl coA so firstly pyruvic acid changed in acetyl coA. For this TPP co-enzyme and Mg++ are important. In this process oxidation and decarboxilation held together so this process called oxidation decarboxilation. For this process pyruvic dehydrogenase complex is important. This complex is group of three enzymes.These enzymes are-
1.Pyruvate decarboxynilase
2Lipoate reductase trans acetylase
3.De hydrolipoate dehydrogenase
Energy yieldduring oxidative decarboxilation-
2 pyruvic acid+2NAD-2 acetyl coA+ 2NADH2
2NADH2- 6ATP
For first step of aerobic respiration click here-GLYCOLYSIS
KREBS CYCLE/TCA CYCLE/CITRIC ACID CYCLE
Krebs cycle was discovered by Hans Krebs.It occur inside mitochondria.It is a amphibolic path way because it is a comon path wat for protien,lipids catabolism. Acetyl coA functions as sbstrate entrant for Kreb cycle.This cycle complates in 10 steps.These are-
1.Condensation-Acetyl coA combines with oxalo acetate in the presence of citrate synthetase to form citric acid.
Acetyl coA+OAA→citric acid+CoA-Sh
2.Dehydration-Citrate forming Aconitic acid with releasing of water molecule in the presence of aconitase.
Citrate→cis aconitic acid
3.Hydration-cis aconitate is converted into isocitrate with the addition of water in the presence of aconitase.
Cis aconitate+water molecule→Isocitrate
4.Dehydrogenation-Isocitrate is dehydrogenated to oxalosuccinate in the presence of enzyme isocitrate dehydrogenase and Mn++.NADH2 is produced.
isocitrate+NAD+→oxalosuccinate+NADH2
5.Decarboxilation-Oxalosuccinate is decarboxylated to from α-ketoglutarate through enzyme decarboxylase.
Oxalosuccinate→ α-ketoglutarate
6.Dehydrogenation and Decarboxylation- α-ketoglutarate is both dehydrogenated and decarboxylated by an enzyme complex α-ketoglutarate dehydrogenase.the enzyme complex contains TPP and lipoic acid.The product combines with coA to from succinyl CoA.
α-ketoglutarate+CoA+NAD→SuccinylCoA+NADH+H+
7.Formation of ATP/GTP-Succinyl CoA is acted upon by enzyme succinyl thiokinase to form succinate.The reaction release sufficient energy to form ATP or GTP.
Succinyl
CoA+GDP/ATP→ Succinate+CoA+GTP/ATP
8.Dehydrogenation-Succinate undergoes dehydrogenation to form fumarate with the help of a dehydrogenase.FADH2 is produced.
Succinate+FAD→Fumarate+FADH2
Fumarate+H2O→Malate
10.Dehydrogenation-Malate is Dehydrogenated or oxidised through the energy of malate dehydrogenase to produce oxaloacetate. Hydrogen is accepted by NADP+NAD+
Malate=NAD(P)+→Oxaloacetate+NAD(P)H+
Oxaloacetate picks up another molecule of activated acetate to repeat the cycle.
A molecule of glucose yields two molecules of NADH2,2ATP and two pyruvate while undergoing glycolysis. The two molecules of pyruvate are completely degraded in Krebs cycle to form 2 molecules of ATP,8NADH2 and 2FADH2.
Energetics of Krebs cycle reaction No. of ATP
2.Isocitric aid to oxallosuccinic acid(NAD) 3ATP
3. α-Ketogutric acid to succinyl cova(NAD) 3ATP
4.Succinic acid to fumaric acid(FAD) 2ATP
5.Malic acid to OAA(NAD) 3ATP
6.Succinyl coA to succinic acid 1ATP
=15ATP
Total ATP produced during
complate oxidation of Pyruvic acid =2x15=30ATP
And during glycolysis=8ATP
TOTAL ATP=38ATP
