Catabolism of pyruvate Flashcards
How is NAD+ derived?
From a vitamin called niacin
How is NAD+ regenerated?
Through the oxidative metabolism of pyruvate
What does NADH deliver to the respiratory chain?
Electrons
What is NAD+
An electron acceptor
What are the 3 names for stage 2?
Citric acid cycle
Krebs cycle
Tricarboxylic acid (TCA) cycle
Where does the TCA cycle occur?
In the mitochondria -the inner membrane contains proteins for the electron transport chain, ATP synthase and transport proteins
The matrix contains the enzymes needed for the TCA cycle
How does pyruvate enter the mitochondrial matrix?
It follows the H+ gradient from the cytosol to the matrix
There is a pyruvate transporter that trasports H+ and pyruvate by facilitated diffusion
There is a similar process that regulated ADP, ATP and Pi movement into and out of the cell
What enzyme catalyses the oxidative decarboxylation of pyruvate to acetly-CoA?
Pyruvate dehydrogenase complex (PDC)
How is PDC regulated?
Phosphorylation, it consists of 3 enzymes in a complex`
What does PDC determine?
Glucose oxidation in well oxygenated tissues
Is the reaction from pyruvate to acetly-CoA reversible?
No
What reaction does PDC initiate?
Pyruvate loses a carbon dioxide to form HETPP
How many reactions are in the TCA cycle?
Eight reactions in total
What will acetyl Co-A bind with to form?
The 2 carbon acetyl Co-A will bind with a four carbon unit to form a six-carbon unit
What reaction will this six carbon unit undergo?
Decarboxylation twice, forming 2 CO2 molecules
How many oxidation reactions are there?
4, yielding NADH, H+ and FADH2
In what form is energy stored?
One GTP is formed in the TCA cycle
Where are all the enzymes bar one in the TCA cycle located?
In the mitochondrial matrix
What enzyme is not located in the mitochindrial matrix and where is it located?
Succinate dehydrogenase, it is located in the inner mitochondrial membrane
What reaction does succinate dehydrogenase do?
Succinate + FAD = Fumarate + FADH2
What can all the products from stage 2 metabolism give rise to?
Acetyl-CoA which can be oxidised completely to form CO2
What are all the enzymes of the TCA cycle associated with?
The mitochondria
What does each turn of the TCA cycle involve?
The uptake of 2 carbon atoms in the form of acetyl-CoA and the release of two carbon atoms as CO2
Transfer of 3 pairs of electrons to NAD+ from NADH + H+
Transfer of 1 pair of electrons to reduce FAD to FADH2
What does one substrate level of phosphorylation result in?
The formation of GTP from GDP + Pi
