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20 Cards in this Set

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  • Back
What are the starting materials of TCA?
Carbons from various fuels in the form of the two carbon units of acetyl CoA, NAD+, FAD, GDP, and Pi
What are the TCA products?
o Two CO2 (equivalent to the two entering carbon atoms of acetyl CoA) NADH, FADH2, GTP
What is the main contribution of the TCA cycle?
o Main contribution is indrirect source of energy by producting reducing agents
What is the net reaction for TCA?
• The net reaction is
• Acetyl CoA+3NAD++FAD+GDP+Pi+2H2O=2CO2+CoASH+3NADH+3H++FAD(2H)+GTP
What are the intermediates and thier amounts of in the TCA?
• 6 Citrate
• 6 Isocitrate
• 1 Co2
• 5 Alpha ketoglutarare
• 1 Co2
• 4 Succinyl Coa
• 4 Succinate
• 4 Fumarate
• 4 Malate
• 4 Oxaloacetateg
What are the sources for Acetyl CoA?
o Amino Acids
o Ketons(extrahepatic)
o Fatty Acids
o Ethanol
o Pyruvate(which is comes from glucose and sometimes lactate
Pyruvate via pyruvate dehydrogenase
What is the major source of Acetyl CoA in fed state?
• The major source of acetyl CoA for body wide use in the normal fed state are Pyruvate cia pyruvate dehydrogenase
Major source of Acetyl CoA in fasted state?
• The major source of acetyl CoA for body wide use in the normal fasted state is Fatty acid via Beta oxidation
When is the TCA active?
What does • Co-enzyme A (CoA-sh) do in the TCA cycle
o Mainly derived from Panthothenic acid
o Transfers and activates acyl groups in the TCA cycle
What does NAD do in the TCA
o Niacin reduced to NADH by addition of two electrons at one
o NAD+/NADH are essentially a cosubstrate/co-product pair
What are • Alpha-ketoglutarae DH and Pyruvate DH in the TCA?
In addition to being exothermic what is another benefit of the delta g being negative for the TCA?
It prevents the cycle from going backwards
What are the means of regulating TCA?
• Citrate itself inhibits Acetyle CoA
• Isocitrate
o ADP increases
o NADH decreases
o Ca2+ increases
• Alpha ketoglutarate dehydrogenase
o NADH decreases
o CA2+ increases
. Estimate (using the approximation, 1 NADH 3 ATP; 1 FADH2 2 ATP) how much ATP can be produced by TCA cycle oxidation of one acetyl CoA molecule (Don’t forget the GTP!)
• *So I have 3 NADH=9ATP
• I have FADH=2ATP
• I have 1 GTP Which I believe takes a ATP so
• 9+2+1(GTP=1ATP)=12?ATP
Explain why aerobic conditions are required to produce the energy noted in A8.
*Oxidation is required to oxidize the cofactors from their reduced state.
Locate the reactions of as mitochondrial and/or cytosolic.
. Name the glycolytic product which is the immediate precursor of oxaloacetate for entry into the TCA Cycle. Name the enzyme (and its vitamin-derived cofactor) involved in this process. Name the amino acid which can be transaminated to oxaloacetate. Indicate which of the compounds named can never provide oxaloacetate for hepatic TCA Cycle activity. (See also B6.)

This isn’t the case: Instead, transamination can occur in the cytosol or in the mitochondrion; pyruvate dehydrogenase and pyruvate carboxylase are mitochondrial enzymes.