TCA cycle Flashcards
What does each turn of the cycle produce?
2 molecules of CO2 (waste), 3 molecules of NADH, 1 molecule of FADH and 1 molecule of GTP
Where does the TCA cycle occur?
The mitochondrial matrix: with the soluble enzymes required suspended here
What is the first step of the TCA cycle?
4C oxaloacetate combines with 2C acetate, to form 6C citrate.
What happens just prior to the TCA cycle?
Pyruvate is decarboxylated and oxidised using pyruvate dehydrogenase and NAD+, forming acetyl CoA and NADH.
When does the TCA cycle occur?
In aerobic conditions
What happens to acetyl CoA during this reaction?
The thioester bond is readily hydrolysed, leaving just acetate (2C) to donate to oxaloacetate.
What is Beri Beri disease caused by?
Pyruvate dehydrogenase dysfunction, due to deficiency of thiamine: a cofactor of the enzyme complex. So, full glucose metabolism does not occur.
What are symptoms of Beri Beri?
Damage to PNS, weakness of musculature and decreased cardiac output- the brain relies heavily on glucose metabolism so is vulnerable to this disease
How do amino acids enter the TCA cycle?
The amine group is removed (then excreted as urea) and the carbon skeleton can convert to acetyl CoA, or acetoacetyl CoA
What are amino acids called which can enter the TCA cycle?
Ketogenic amino acids
What else can deamination of amino acids form?
Glucogenic amino acids, which are involved in gluconeogenesis.
How do amino acids form molecules in TCA?
Transamination using an enzyme: 1 amine group is transferred from one amino acid to a keto acid, therefore forming a new keto acid (e.g. pyruvate) and amino acid.
