1.9 Citric Acid Cycle Flashcards
What is an anaplerotic reaction
when intermediates of the citric acid cycle need to be replenished if they are diminished
When is Pyruvate Dehydrogenase ACTIVE?
When it is dephosphorylated
What four molecules speed up the reaction of Pyruvate Dehydrogenase
AMP, CoA, NAD+ and Ca2+
How does pyruvate get into mitochondria?
It diffuses through the outer membrane through Porins
How does pyruvate enter the matrix of mitochondria
Pyruvate translocase
Where is pyruvate translocase located and what is its function?
It is embedded in the inner membrane of mitochondria
It transports pyruvate into the matrix of mitochondria
What is the link between glycolysis and citric acid cycle
Oxidative decarboxylation of pyruvate to acetyl CoA (pyruvate dehydrogenase complex)
What are the products of the pyruvate to Acetyl CoA reaction?
Acetyl CoA
CO2
NADH
Is the pyruvate to Acetyl CoA reaction reversible?
No, the high negative delta G makes the reaction hard to reverse. It is practically irreversible
How many enzymes are involved in the Pyruvate Dehydrogenase complex? What are they?
- Pyruvate Dehydrogenase
- Dihydrolipoyl Transacetylase
- Dihydrolipoyl Dehydrogenase
What are the 5 coenzymes of the pyruvate dehydrogenase complex
- Thiamine
- Riboflavin
- Niacin
- Pentothanate
- Lipoate (Lipoic Acid)
Name the 4 vitamin precursors of the 5 coenzymes of pyruvate dehydrogenase complex
- B1 (Thiamine)
- B2 (Riboflavin)
- B3 (Niacin)
- B5 (Pentothenate)
Acetyl group is activated by formation of what?
high energy thioester bond
Where does the citric acid cycle take place?
Mitochondrial matrix
How many CO2 are released during one turn of the citric acid cycle
2 CO2 are released during the citric acid cycle
How many redox reactions are found in the citric acid cycle
4
How many NADH and FADH2 are released in the Citric Acid cycle
3 NADH and 1 FADH2
How many high energy phosphate bonds are made during citric acid cycle
1 GTP (can be turned into ATP)
For one molecule of Glucose, how many CO2 are produced through glycolysis through citric acid cycle
6 –>
2, 1 per pyruvate in pyruvate to acetyl CoA
4, 2 per pyruvate in citric acid cycle
How many NAD+ molecule are reduced to NADH for one glucose throughout citric acid cycle
10
2, Glycolysis
2, 1 per pyruvate in pyruvate to acetyl CoA
6, 3 per pyruvate in citric acid cycle
Theoretically, how many ATP are possible through oxidation of one glucose molecule
32
What four reactions control the Citric Acid cycle
- Pyruvate Dehydrogenase complex
- Citrate Synthase
- Isocitrate Dehydrogenase
- alpha-Ketoglutarate Dehydrogenase
What four things slow down the conversion of acetyl CoA to Citrate through Citrate Synthase
- ATP
- Acetyl CoA
- NADH
- Succinyl CoA
What two things Slow Down the Isocitrate Dehydrogenase reaction
- ATP
2. NADH
What speeds up the isocitrate dehydrogenase reaction?
ADP
What four things slow down alpha-ketoglutarate dehydrogenase reaction
- ATP
- GTP
- NADH
- Succinyl CoA
What three steps of the Citric Acid Cycle are regulatory and considered Strongly Exergonic steps
- Citrate Synthase
- Isocitrate Dehydrogenase
- Alpha-Ketoglutarate Dehydrogenase
What two main molecules inhibit the regulatory steps of citric acid cycle
ATP and NADH
What five things allosterically inhibit pyruvate dehydrogenase reaction
- ATP
- NADH
- GTP
- Acetyl CoA
- Long chain fatty acids
Which four things activate pyruvate dehydrogenase reaction
- AMP
- CoA
- NAD+
- Ca2+
What regulation is faster in regard to the citric acid cycle and pyruvate dehydrogenase reaction, Allosteric or Covalent
Allosteric
Other than ATP and NADH, what regulates Glycolysis and Citric Acid Cycle
The concentration of Citrate regulates PFK1
