Unit I Krebs Cycle Flashcards
Whats another name for Krebs cycle?
citric acid cycle, or tricarboxylic acid cycle
What system has the greatest production of ATP?
Krebs cycle (aerobic respiration)
Where does krebs take place?
mitochondrial matrix
What 3 things does krebs break down?
fats, carbs,and proteins
What other pathway runs with krebs?
electron transport system
Where does ETS take place?
inner mitochondrial matrix
What are krebs’ main products?
NADH, FADH2, GTP, and CO2
What are ETS’ main products?
ATP, CO2, and H20
What the main reactants of Krebs?
fats, carbs, proteins, Acetyl CoA
What are the main reactants of ETS?
ADP, Pi, NADH, FADH2, and Oxygen
What key enzymes are used in aerobic respiration?
dehydrogenases
How does a carb enter the kreb cycle?
As acetyl CoA after running through glycolysis and a prep step
How does a fat enter Krebs?
As acetyl CoA after being beta oxidized
How does a protein enter the krebs cycle?
Each AA has a unique way to enter, but mostly acetyl CoA
Shortly describe how glucose would enter krebs?
Glucose would become pyruvate then converted to Acetyl CoA after a prep step. Acetyl CoA can then enter the cycle
How does Acyl CoA enter the krebs cycle?
Its converted to Acetyl CoA after Beta Oxidation
What is the important carrier of both Acyl and Acetyl CoA?
Coenzyme A
How would a fatty acid enter krebs again?
through beta oxidation
Where in the cell would Beta Oxidation take place?
in the mitochondrial matrix
How would amino acids enter krebs usually?
as Acetyl CoA
Besides Acetyl CoA, how else can amino acids enter krebs?
oxaloacetate, alpha ketoglutarate, succinyl CoA, and fumarate
Pyruvate is converted in to acetyl CoA by what enzyme?
pyruvate dehydrogenase complex
Where does the pyruvate conversion to acetyl CoA take place?
inside the mitochondrial matrix
What couples with pyruvate dehydrogenase?
NAD is reduced to NADH and a CO2 is given off
How many enzymes are in the pyruvate dehydrogenase complex?
3
How many co-enzymes are in the pyruvate dehydrogenase complex?
5
List the co-enzymes of the pyruvate dehydrogenase complex?
thiamine pyrophosphate, FAD, NAD, coenzyme A,and lipoate
In the first step of Krebs, acetyl CoA and oxaloacetate are catalyzed by what enzyme to create citric acid (citrate)?
citrate synthase
What is citrate synthase coupled with to create citrate?
H20 and Coenzyme A
Aconitase converts citric acid to what?
isocitric acid (isocitrate)
What is the unstable intermediate of isocitrate to alpha ketoglutarate?
oxalosuccinate
what converts isocitrate to oxalosuccinate?
isocitrate dehydrogenase
What coverts oxalosuccinate to alpha ketoglutarate?
isocitrate dehydrogenase
Isocitrate to alpha ketoglutarate is said to be oxidative carboxylation because
NAD gains an electron and CO2 is given off
What enzyme converts alpha ketoglutarate to succinyl CoA?
the alpha ketoglutarate dehydrogenase complex
The reaction of alpha ketoglutarate to succinyl CoA is said to be oxidative decarboxylation because
NAD gains an electron and CO2 is given off
what co-enzyme is coupled with alpha ketoglutarate dehydrogenase complex?
Coenzyme A
How many enzymes are in the alpha ketoglutarate complex and what type of enzymes?
3; dehydrogenase transferase dehydrogenase
how many coenzymes are in the alpha ketoglutarate complex?
TPP, FAD, NAD, Coenzyme A, and lipoate
What steps have given off CO2 so far?
pyruvate dehydrogenase complex, isocitrate dehydrogenase, and alpha ketoglutarate dehydrogenase complex
Succinate thiokinase converts what to succinate?
succinyl CoA
What is another name for succinate thiokinase?
Succinyl CoA synthetase
What are the other products besides succinate that succinate thiokinase makes?
GTP and Coenzyme A
What is the one reaction in the TCA that yields a high energy phosphate bond?
succinyl CoA to succinate
How does GTP become ATP?
react GTP with ADP and nucleoside diphosphokinase
Is the conversion of GTP to ATP reversible?
it is reversible
When succinate dehydrogenase reacts with succinate what is made?
fumarate
What is coupled with succinate dehydrogenase?
FAD
What is succinate dehydrogenase bound to?
the inner mitochondrial membrane
For fumarate to become malate what must happen?
Fumarate gets hydrated by fumarase
what is coupled with fumarase?
H20
What converts malate to oxaloacetate?
malate dehydrogenase
What is coupled with malate dehydrogenase?
NAD
List some conditions that would inhibit pyruvate dehydrogenase
High NADH, acetyl CoA, ATP, and LCFA’s
How is pyruvate dehydrogenase inhibited by high energy conditions?
a kinase is activated by these conditions and adds a phosphate to pyruvate dehydrogenase making it inactive
What are the key regulatory steps of krebs?
pyruvate dehydrogenase complex, citrate synthase, isocitrate dehydrogenase, and alpha ketoglutarate dehydrogenase complex
Which products in high concentration would inhibit citrate synthase?
ATP and citrate
Which reactants in low concentration would inhibit citrate synthase?
oxaloacetate or acetyl CoA
What products in high concentration would inhibit isocitrate dehydrogenase?
ATP and NADH
What reactants in high concentration would stimulate isocitrate dehydrogenase?
ADP and NAD
What would be examples of products inhibiting the alpha-ketoglutarate dehydrogenase complex?
ATP, NADH, and Succinyl CoA
Define anaplerotic
giving substrates to a cycle
Define Cataplerotic
taking substrates from the cycle
What are the final common products of aerobic metabolism?
CO2 and H20
What is the purpose of krebs cycle again?
ATP