Aerobic Carbohydrate Metabolism Flashcards
How does the permeability of the outer and inner membranes of the mitochondria differ?
the outer membrane is highly porous while the inner is more selective (water and small gas molecules are the only things that can diffuse)
How does pyruvate get into the mitochondria?
Pyruvate dehydrogenase complex (which is made up of 3 other enzymes). Pyruvate can diffuse through the outer membrane but remember that the inner membrane is less permeable.
What are the three enzymes that make up the PDC?
Pyruvate dehudrogenase, Dihydrolopayl transacetylase, and Dihydroilipyl dehydrogenase YOUDONT NEED TO REALLY KNOW THIS
What molecule is cycled through the CTA?
Oxaloacetate
What do you get from one turn of the TCA?
4 NADH (1 from PDC and 3 from cycle), 1 GTP, 1 FADH2, 2 CO2. This is from ONE pyruvate
Acetyl Coa bonds to oxaloacetate to form….
citrate
Where is the PDC located?
Inner mitochondrial membrane
How does the reduction potential change from complex to complex in the ETC?
Every subsequent complex has a higher reduction potential
True or False: ETC complex 2 is succinate dehydrogenase
True
True or False: FADH2 yields less energy than NADH2 because it enters the ETC at complex 2
True
Place the following electron transport chain complexes and electron carriers in the order that a pair of electrons would encounter them, from first to last: Complex III, Q, Cytochrome C, Complex II, Complex IV
Complex II
Q
Complex III
Cytochrome C
Complex IV
True or false: The final electron acceptor of the electron transport chain is oxygen, which has the highest reduction potential of all electron transport chain components.
This statement is true. Oxygen is the final electron acceptor of the ETC. Since electrons flow from electron carriers with lower reduction potentials to carriers with higher reduction potentials, oxygen must have the highest reduction potential in the entire chain.
You are an electron. How would you go through the ETC.
NADH drops off its electrons at complex I. Electrons that enter complex I are taken up by ubiquinone, which bypasses complex II and travels directly to complex III. Electrons held by FADH2 enter the ETC at complex II rather than at complex I. As they exit complex II, they are transferred to ubiquinone, which travels to complex III. Complex III gives up the electrons to cytochrome C, which deposits them at complex IV.
Where does the first regulatory point occur for aerobic resp (TCA+ETC)?
at the PDC
What upregulates the PDC?
AMP, NAD+, and CoA
What are the three key steps in the CTA that are regulated?
Step 1 w/Oxaloacetate and AcetylCoA, Isocitrate to alpha ketoglutarate, alpha ketoglutarate to succinyl coa
How is the first step of TCA regulated?
Upregulated by ADP, Downreged by ATP and NADH and Citrate and Succinyl CoA
How is the conversion of Isocitrate to alpha ketoglutarate regulated?
Upreg ADP and downreg ATP
How is the conversion of alpha ketoglutarate to succinyl coa regulated?
Inhibited if you have too much succinl coa or too much NADH
High levels of which molecules will upregulate the pyruvate dehydrogenase complex?
NAD+ , Coenzyme A, and AMP
Which TCA step generates FADH2?
Succinate to Fumarate via succinate dehydrogenase
True or false: NADH produces more ATP than FADH2 because electrons from NADH enter the electron transport chain at complex II.
This statement is false. NADH produces more ATP than FADH2 because NADH drops off its electrons at complex I. Unlike complex II, which receives electrons from FADH2, complex I pumps protons from the matrix into the intermembrane space. Since the number of protons pumped across the inner membrane determines how much ATP is ultimately produced by ATP synthase, electrons from NADH yield more ATP than electrons from FADH2.
What would high levels of CoA indicate?
High levels of coenzyme A suggest that the cell does not have enough acetyl-CoA and therefore not enough energy, so aerobic metabolism will be upregulated.
What does the PDC step generate per molecule of pyruvate?
AcetylCoa, NADH, and CO2
What are the differences between pyruvate dehydrogenase complex, pyruvate decarboxylase, and pyruvate carboxylase?
dehydrogenase complex: this is the complex required to transport pyruvate across the inner mitochondrial membrane and turn it to AcetylCoa
pyruvate decarboxylase: this is the first step in ethanol fermentation
pyruvate carboxylase: this is the first step in making oxaloacetate from pyruvate in gluconeogenesis
What do you get from one turn of the TCA?
Excluding PDC, you get 1 GTP, 1FADH2, 3 NADH, 2 CO2
What are the major irreversible steps of the TCA?
Step 1 Citrate Synthase (AcetylCoA+Oxaloacetate»Citrate), Step 4 Alpha ketoglutarate dehydrogenase (alpha Ketoglutate to succinyl coA)
At what complex are electrons transferred to with NADH
Complex I
At what complex are electrons transferred to with FADH2
Complex II
Why are electrons for FADH associated with complex II and not complex I ?
Because complex 2 is succinate dehydrogenase which is the enzyme that catalyzes the 6th step of the TCA
What kind of molecule is cytochrome c?
It is a heme group that uses Fe2+/Fe3+
What element is at the center of cytochrome C?
Iron
What molecule do complexes I and II deposit their electrons?
Ubiquinone which gets reduced to ubiquinol upon electron transfer
The final step of the TCA where malate is converted to oxaloacetate via malate dehydrogenase is thermodynamically unfavorable. Why does it still proceed?
It is kinetically favorable. Oxaloacetate is continuously used so le chatleirs principle applies.
