Question

In the situation of Malate Dehydrogenase generating Oxaloacetate, the ∆G^o = + 29.7 kJ/mol. What is the equilibrium ratio of Malate versus Oxaloacetate in this reaction?

	a.	Cannot determine
	b.	2.63 x 10-6
	c.	6.22 x 10-6
	d.	9.0 x 10-6
	e.	1.3 x 10-6

Citrate Synthase uses Oxaloacetate and Acetyl-CoA to synthesize Citrate, with a highly exergonic ∆G^o = - 31.5 kJ/mol. Why would this be necessary for the TCA Cycle? HINT: What was asked in Question 7 and which answer is MOST correct given these data?

	a.	Oxaloacetate is a required intermediate for the TCA Cycle.
	b.	Highly favorable citrate synthesis drives the unfavorable Malate Dehydrogenase reaction.
	c.	Oxaloacetate is a required intermediate for Gluconeogenesis.
	d.	Malate conversion to Oxaloacetate is highly unfavorable.
	e.	Citrate synthesis is a rate-determining step in the TCA Cycle.

I need help with second question more specifically!

Answer 1

In the situation of Malate Dehydrogenase generating Oxaloacetate, the ∆Go = + 29.7 kJ/mol. What is the equilibrium ratio of Malate versus Oxaloacetate in this reaction?

	a.	Cannot determine
	b.	2.63 x 10-6
	c.	6.22 x 10-6
	d.	9.0 x 10-6
	e.	1.3 x 10-6 del Go is given for malate to OAA and eq ratio of malate is required (malate is product here) so delGo becomes negative

log K eq= delG/2.303 RT=-29700/5935= -5.003698

Keq=9.0x10-6

Citrate Synthase uses Oxaloacetate and Acetyl-CoA to synthesize Citrate, with a highly exergonic ∆Go = - 31.5 kJ/mol. Why would this be necessary for the TCA Cycle? HINT: What was asked in Question 7 and which answer is MOST correct given these data?

	a.	Oxaloacetate is a required intermediate for the TCA Cycle.
	b.	Highly favorable citrate synthesis drives the unfavorable Malate Dehydrogenase reaction.
	c.	Oxaloacetate is a required intermediate for Gluconeogenesis.
	d.	Malate conversion to Oxaloacetate is highly unfavorable.
	e.	Citrate synthesis is a rate-determining step in the TCA Cycle.

I need help with second question more specifically

Citrate synthesis is not rate limiting instead highly favorable. What ever amount of Oxalo Acetate available in the mitrochondria is consumed by TCA cycle. This is because this intermediate is also a part of gluconeogenesis hence if the formation of citric acid step would not be favorable then its may participate in gluconeogenesis hence energy will not be produced by TCA cycle. So option c is right.