Contribution of Krebs to oxydative phosphorylation?

[Aymeric]

Hello,

After going over my biochemistry chapter on glycolysis, the TCA cycle and the electron transport chain, it seems to me like the only role that Krebs plays (in the context of ATP generation I mean) is to produce enough H+ and electrons to fuel the electron transport chain mechanism. Is there any other point to it?

Are all reactions in Krebs specifically intended to cause as many oxydations as possible to feed the ETC? Should krebs be seen in that perspective?

Thanks in advance.
PS: What I'd like is to understand is the point behind all those reactions and why they happen the way they happen.

 

[Ygggdrasil]

In terms of metabolizing glucose, you are correct. The Krebs cycle oxidizes the acetyl-CoA generated by glycolysis to CO₂ to generate NADH and FADH₂ which can feed into the ETC. However, the Krebs cycle is involved in a number of other metabolic processes. For example, many intermediates of the Krebs cycle are involved in amino acid metabolism, so the Krebs cycle can be used to generate material for amino acid synthesis or aid in the breakdown of amino acids for energy production. Indeed, because the Krebs cycle intermediates come from the breakdown of glucose, using these intermediates to produce amino acids essentially amounts to converting carbohydrates into amino acids. Similarly, because Krebs cycle reactions are also involved in gluconeogenesis, feeding amino acids into the Krebs cycle during gluconeogenesis also allow conversion of amino acids into carbohydrates.