Krebs cycle?

[Lodgic]

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Ok, ive read about it in books, but ive never rlly got my mind on the concept in detail...

So i ask - What is Kreb's cycle, what does it involve, etc..any other info...

It seems very complex with a LOT of reactions taking place in the cycle overall..
thnx for ur information input

[HappyFeet]

The Kreb Cycle (Citric Acid Cycle, Tricarboxylic Acid Cycle) is a process that involves a series of enzyme controlled reactions. It is part of the aerobic respiration system and takes place inside the mitochondria.

It's a bit hard to explain the procedures involved without a diagram.

[TesseracT22]

Basically: AcetylCoA in - many organic intermediates - 2CO2 out and also 1 Flavin Adenine Dinucleotide(FADH2) and 2 Nicotinamide Adenine Dinucleotides(NADH).

In terms of chemistry, the AcetylCoA which is a product of Pyruvate Oxidation, is oxidized further and the FADH2 and NADH are electron carriers which are reduced so that they can provide electrons for the next part of Aerobic Respiration.

[brenton1987]

It's easier to understand if you take in glycolysis as well, because it shows where the Acetyl-CoA comes from.

Glycolysis
Glucose + ATP --> Glucose-6-phosphate + ADP
Glucose-6-phosphate --> Fructose-6-phosphate
Frucose-6-phosphate + ATP --> Fructose-1,6-bisphosphate
Fructose-1,6-bisphosphate --> Dihydroxyacetonephosphate + Glyceraldehyde-3-phosphate
Dihydroxyacetonephosphate + Glyceraldehyde-3-phosphate --> 2 Glyceraldehyde-3-phosphate
2 Glyceraldehyde-3-phosphate + NAD⁺ + P_i --> 2 1,3-Bisphosphoglycerate + NADH + H⁺
2 1,3-Bisphosphoglycerate + ADP --> 2 3-Phosphoglycerate + ATP
2 3-Phosphoglycerate --> 2 2-Phosphoglycerate
2 2-Phosphoglycerate --> 2 Phosphoenolpyruvate + H₂O
2 Phosphoenolpyruvate + ADP --> 2 Pyruvate + ATP
2 Pyruvate + CoA + NAD⁺ --> 2 Acetyl-CoA + NADH + H⁺ + CO₂

Overall Reaction
Glucose + 2NAD⁺ + P_i + CoA --> 2 Acetyl-CoA + 2NADH + 2H⁺ + H₂O + CO₂

Krebs Cycle
Oxaloacetate + Acetyl-CoA --> Citrate + CoA
Citrate --> cis-Aconitate + H₂O
cis-Aconitate + H₂O --> Isocitrate
Isocitrate + NAD⁺ --> Oxalosuccinate + NADH + H⁺
Oxalosuccinate --> a-Ketoglutarate + CO₂
a-Ketoglutarate + CoA + NAD⁺ --> Succinyl-CoA + NADH + H⁺ + CO₂
Succinyl-CoA + GDP + P_i --> Succinate + GTP + CoA
Succinate + FAD --> Fumarate + FADH
Fumarate + H₂O --> Malate
Malate + NAD⁺ --> Oxaloacetate + NADH + H⁺

Overall Reaction
Acetyl-CoA + 3NAD⁺ + FAD + GDP + P_i + H₂O --> 3NADH + FADH + 3H⁺ + 2CO₂ + GTP + 2CoA

[lil_georgie_gal]

Wow u guys do this in HSC bio now:O

I did this in first yr uni for the processes involved in metabolism suhc as glycolysis, glucogenolysis etc..

[Lodgic]

LOL!!! no, we dont do Kreb's cycle in the HSC - i'm just one of those science ethusiast guys who reads all this extra information and asks questions beyond what its necessary for me to know.

can't wait to learn this sorta stuff at uni next yr.