Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
53 Cards in this Set
- Front
- Back
What is the fate of the electrons in NADH and FADH2 that gets made by the TCA cycle?
|
They donate the e- to th ETC
|
|
How many ATP are made per NADH and per FADH2 by oxidative phosphorylation?
|
NADH = 3 ATP
FADH2 = 2 ATP |
|
What is the other source of ATP from the TCA cycle?
|
The GTP that is made at step #5 is converted by reaction with ADP to form ATP + GDP
|
|
What is the total energy generated by one round of the TCA CYCLE starting with 1 AcCoA?
|
12 ATP
|
|
What is the predominant factor that regulates the TCA cycle?
|
The cell's need for energy in the form of ATP
|
|
How does low cell ATP signal the TCA cycle to kick in more?
|
When ATP is low, ADP and Pi are high
|
|
What are 3 ways by which ADP stimulates the TCA cycle?
|
-Allosteric activation of Isocitrate dehydrogenase
-Accelerated ETC (results in) -Increased NAD+ |
|
How does ample ATP slow down the TCA cycle?
|
NADH builds up and is a negative inhibitor of Isocitrate dehydrogenase.
|
|
What results from decreased Isocitrate dehydrogenase activity?
|
Isocitrate buildsup and pushes the equilibrium catalyzed by Aconitase in the Citrate direction
|
|
What is the result of buildup of Citrate?
|
Neg feedback inhibition of Citrate synthase.
|
|
What happens to oxaloacetate when NADH is high?
|
OAA is converted back to Malate
|
|
What are 3 vitamins required for reactions of the TCA cycle?
|
The Really Nice People
-Thiamine (TPP) -Riboflavin (FAD) -Niacin (NAD) -Pantothenate (Coenzyme A) |
|
What enzyme is necessary for generating AcCoA from glucose for entering into the TCA cycle?
|
Pyruvate dehydrogenase complex
|
|
Where is PDH found within the cell?
|
Only in the mito matrix
|
|
What is the reaction that the PDH complex catalyzes?
|
Pyruvate is oxidatively decarboxylated to form AcCoA
|
|
What are the 5 coenzymes and thus 4 vitamins needed for the PDH complex to function?
|
-TPP (Thiamine B1)
-Lipoic acid -NAD (Niacin) -FAD (Riboflavin B2) -CoASH (Pantothenate B5) |
|
What is a major contrast between the PDH complex and the similar enzyme a-KG dehydrogenase?
|
PDH exists in an inactive phosphorylated form, and is active when nonphosphorylated
|
|
What is responsible for phosphorylating the PDH complex?
|
A kinase that is associated with the multienzyme complex.
|
|
When is the Kinase active?
|
When products are high and want to feedback inhibit PDH activity
|
|
What molecules stimulate PDH Kinase phosphorylation?
|
-NADH
-AcCoA |
|
When is the Kinase activity low?
|
When substrates are elevated, which decrease Kinase activity so PDH is nonphosphorylated and active.
|
|
So what are 3 molecules that inhibit PDH Kinase activity so that PDH is active?
|
-NAD+
-CoAsh -ADP does it too! |
|
In addition to substrate inhibition of the PDH kinase, what can increase the activity of the PDH complex?
|
A phosphatase
|
|
What function does the TCA cycle serve in addition to transferring e- to NAD/FAD for the TCA cycle and oxidative phosphorylation?
|
Synthetic function!!
|
|
What are TCA cycle intermediates used for in the FASTING state? Where?
|
Production of Glucose in the Liver
|
|
What are TCA cycle intermediates used for in the FED state?
|
Fatty acid synthesis
|
|
In addition to making glucose and FA's, what are TCA cycle intermediates used for making?
|
Amino acids (or AA interconversion)
|
|
What are rxns that replenish TCA cycle intermediates as they are removed for Glucose/FA/AA synthesis called?
|
Anaplerotic reactions
|
|
What is a key enzyme that replenishes Oxaloacetate for the TCA? What substrate does it use?
|
-Pyruvate carboxylase
-Substrate is Pyruvate |
|
What cofactor is utilized by Pyruvate carboxylase?
|
Biotin (B7)
|
|
What is Biotin commonly involved as a cofactor in?
|
CO2 fixation reactions
|
|
In what 3 tissues is Pyruvate carboxylase found? Where is it NOT found?
|
In: liver, brain, fat
NOT In: muscle |
|
What is Pyruvate carboxylase activated by?
|
AcCoA
|
|
What are 4 things neeed for PC to work?
|
-Pyruvate
-CO2 -ATP -Biotin |
|
And what does Pyruvate carboxylase produce?
|
Oxaloacetate
|
|
What is another substrate for anaplerotic reactions to replenish TCA intermediates?
|
Amino acids
|
|
What are 9 AA's that can be used in anaplerotic reactions?
|
GAV TIM PAT
|
|
What is GAV TIM PAT?
|
-Glutamate
-Aspartate -Valine, Threonine, Ile, Met -Phenylalanine, Tyr, Aspartate |
|
What TCA intermediate does Glutamate get converted to?
|
alpha-Ketoglutarate
|
|
And what 4 aa's can form Glutamate?
|
GAPH
-Glutamine -Arginine -Proline -Histidine |
|
What TCA intermediate does Aspartate get converted to? How?
|
Oxaloacetate - by transamination
|
|
What aa can form Aspartate?
|
Asparagine
|
|
What TCA intermediate is formed from Valine, Threonine, Ile, and Methionine?
|
Succinyl CoA (via Propionyl CoA and methylmalonyl CoA)
|
|
What TCA intermediate is formed from Phenylalanine, Aspartate, and Tyrosine?
|
Fumarate
|
|
What TCA intermediates are used for gluconeogenesis?
|
Malate or Oxaloacetate
|
|
What precursors can form Pyruvate?
|
Alanine and Lactate
|
|
What converts Pyruvate to OOA to replenish it when OOA/Malate are removed for gluconeogenesis?
|
Pyruvate carboxylase
|
|
What TCA intermediate is used for Fatty Acid synthesis?
|
Citrate
|
|
How does glucose get converted to citrate?
|
1. By PDH production of AcCoA
2. By PC production of OOA |
|
What is the enzyme that catalyzes the anaplerotic reaction to replenish the TCA cycle intermediates?
|
Pyruvate carboxylase
|
|
How is Glucose and the TCA cycle involved in AA synthesis?
|
Glucose makes Pyruvate which gets converted to OAA by PC, then to amino acids..
|
|
What does OAA get transaminated to?
|
Aspartate and Asparagine
|
|
What 4 amino acids can be made from a-ketoglutarate?
|
GAPG
-Glutamate -Glutamine -Arginine -Proline |