Glycolysis, Krebs cycle & Electron Transport Chain Flashcards
Why must we undergo fermentation?
In the absence of oxygen, this is the only way to generate NAD+ so that glycolysis can continue producing energy in the form of ATP
How does the presence/absence of oxygen determine the fate of pyruvate in cells?
Pyruvate is the product of glycolysis
It can be further oxidized, to release more energy
What happens during the link reaction (pyruvate processing)?
Pyruvate will be converted to acetyl CoA
2NADH and 2CO2 are released per molecule of glucose
What happens during Krebs cycle?
Occurs in the mitochondria matrix 1 turn of the cycle: 2 molecules of CO2 (waste product) 3 molecules of NADH 1 molecule of GTP/ATP 1 molecule of FADH2 are produced
What happens during at the electron transport chain (ETC)?
NADH and FADH2 transfer electrons to the ETC
NADH undergoes oxidation, forming NAD+, causing hydrogen ions to be pumped out
FADH2 undergoes oxidation, forming FAD+, no hydrogen ions are pumped out
Electrons from complex 1 and 2 will be transferred to complex 3 then 4, where hydrogen ions would be pumped out
Water is produced at complex 4
Why is the Krebs cycle referred to as a circular metabolic pathway?
Oxaloacetate is being regenerated again at the end of the cycle
Where is acetyl CoA obtained from?
From decarboxylation of pyruvate (from glycolysis)
Is energy produced directly during the Krebs cycle?
Yes, 1 GTP is produced (in 1 turn)
What are the products of the Krebs cycle?
2CO2, 1 GTP, 3 NADH, 1 FADH2 - 1 turn of the Krebs cycle
Where did NADH and FADH2 come from?
NADH and FADH2 are products of the Krebs cycle
Production of ATP requires energy. How is this energy produced?
When hydrogen ions travel from high to low gradient, it releases energy which will combine ADP to Pi to make ATP.
What happens when the concentration gradient is absent in the ETC?
Hydrogen ions will be able to move freely across it and downwards oxidation of NADH sets up a concentration gradient.
Concentration gradient enables ATP synthesis
Without concentration gradient, the concentration of hydrogen ions are the same in the intermembrane space and mitochondria matrix.
No concentration gradient means no ATP synthesis
