B MCAT - Metabolism Flashcards
Pathway from glucose to electron transport chain
Glucose undergoes glycolysis in cytoplasm to make pyruvate.
Pyruvate undergoes pyruvate dehydrogenase pathway (enzyme PDH) in mitochondrial matrix to make acetyl Co-A, which is used in the citric acid cycle to make ATP, plus NADH and FADH2 which enter the electron transport chain at complexes I and II, respectively.
Pathway from fatty acids to the electron transport chain
Fatty acids are broken down in mitochondria matrix via beta oxidation to acetyl CoA, which is used in the citric acid cycle to make ATP, plus NADH and FADH2 which enter the electron transport chain at complexes I and II, respectively.
Enzymes in the 3 irreversible steps of glycolysis
In step 1, hexokinase.
In step 3, phosphofructokinase (PFK-1). Rate-limiting step.
In step 10, pyruvate kinase.
Operate on negative feedback.
Rate-limiting enzyme of beta oxidation
malonyl-CoA
Indicators of energy deficiency
Ca+
ADP
NAD+
Glycolysis Inputs + Outputs
INPUTS:
1 molecule glucose (6 C chain)
2 NAD+
2 ATP (at steps 1 and 3)
2P
OUTPUTS:
2 pyruvate (3 C each)
2 NADH
4 ATP (at steps 7 and 10)
(4-2=2 net ATP)