Aerobic Carbohydrate Metabolism

Question 1

How does the permeability of the outer and inner membranes of the mitochondria differ?

Answer 1

the outer membrane is highly porous while the inner is more selective (water and small gas molecules are the only things that can diffuse)

Question 2

How does pyruvate get into the mitochondria?

Answer 2

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.

Question 3

What are the three enzymes that make up the PDC?

Answer 3

Pyruvate dehudrogenase, Dihydrolopayl transacetylase, and Dihydroilipyl dehydrogenase YOUDONT NEED TO REALLY KNOW THIS

Question 4

What molecule is cycled through the CTA?

Answer 4

Oxaloacetate

Question 5

What do you get from one turn of the TCA?

Answer 5

4 NADH (1 from PDC and 3 from cycle), 1 GTP, 1 FADH2, 2 CO2. This is from ONE pyruvate

Question 6

Acetyl Coa bonds to oxaloacetate to form….

Answer 6

citrate

Question 7

Where is the PDC located?

Answer 7

Inner mitochondrial membrane

Question 8

How does the reduction potential change from complex to complex in the ETC?

Answer 8

Every subsequent complex has a higher reduction potential

Question 9

True or False: ETC complex 2 is succinate dehydrogenase

Answer 9

True

Question 10

True or False: FADH2 yields less energy than NADH2 because it enters the ETC at complex 2

Answer 10

True

Question 11

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

Answer 11

Complex II

Q

Complex III

Cytochrome C

Complex IV

Question 12

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.

Answer 12

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.

Question 13

You are an electron. How would you go through the ETC.

Answer 13

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.

Question 14

Where does the first regulatory point occur for aerobic resp (TCA+ETC)?

Answer 14

at the PDC

Question 15

What upregulates the PDC?

Answer 15

AMP, NAD+, and CoA

Question 16

What are the three key steps in the CTA that are regulated?

Answer 16

Step 1 w/Oxaloacetate and AcetylCoA, Isocitrate to alpha ketoglutarate, alpha ketoglutarate to succinyl coa

Question 17

How is the first step of TCA regulated?

Answer 17

Upregulated by ADP, Downreged by ATP and NADH and Citrate and Succinyl CoA

Question 18

How is the conversion of Isocitrate to alpha ketoglutarate regulated?

Answer 18

Upreg ADP and downreg ATP

Question 19

How is the conversion of alpha ketoglutarate to succinyl coa regulated?

Answer 19

Inhibited if you have too much succinl coa or too much NADH

Question 20

High levels of which molecules will upregulate the pyruvate dehydrogenase complex?

Answer 20

NAD+ , Coenzyme A, and AMP

Question 21

Which TCA step generates FADH2?

Answer 21

Succinate to Fumarate via succinate dehydrogenase

Question 22

True or false: NADH produces more ATP than FADH2 because electrons from NADH enter the electron transport chain at complex II.

Answer 22

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.

Question 23

What would high levels of CoA indicate?

Answer 23

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.

Question 24

What does the PDC step generate per molecule of pyruvate?

Answer 24

AcetylCoa, NADH, and CO2

Question 25

What are the differences between pyruvate dehydrogenase complex, pyruvate decarboxylase, and pyruvate carboxylase?

Answer 25

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

Question 26

What do you get from one turn of the TCA?

Answer 26

Excluding PDC, you get 1 GTP, 1FADH2, 3 NADH, 2 CO2

Question 27

What are the major irreversible steps of the TCA?

Answer 27

Step 1 Citrate Synthase (AcetylCoA+Oxaloacetate»Citrate), Step 4 Alpha ketoglutarate dehydrogenase (alpha Ketoglutate to succinyl coA)

Question 28

At what complex are electrons transferred to with NADH

Answer 28

Complex I

Question 29

At what complex are electrons transferred to with FADH2

Answer 29

Complex II

Question 30

Why are electrons for FADH associated with complex II and not complex I ?

Answer 30

Because complex 2 is succinate dehydrogenase which is the enzyme that catalyzes the 6th step of the TCA

Question 31

What kind of molecule is cytochrome c?

Answer 31

It is a heme group that uses Fe2+/Fe3+

Question 32

What element is at the center of cytochrome C?

Answer 32

Iron

Question 33

What molecule do complexes I and II deposit their electrons?

Answer 33

Ubiquinone which gets reduced to ubiquinol upon electron transfer

Question 34

The final step of the TCA where malate is converted to oxaloacetate via malate dehydrogenase is thermodynamically unfavorable. Why does it still proceed?

Answer 34

It is kinetically favorable. Oxaloacetate is continuously used so le chatleirs principle applies.