Carbohydrate metabolism II

Question 1

Why is the citric acid cycle inhibited by ATP and NADH but activated by ADP and NAD+?

Answer 1

The citric acid cycle is used to produce energy for the cell, so if the cell already has enough energy (ATP and NADH) then it would be a waste to keep producing more. Similarly, if the cell is lacking energy (ADP and NAD+) then it would benefit the cell to start making more energy

For instance, when the metabolic activity of the cell is high, there will be more ADP and NAD+ than ATP and NADH. This tells the cell to activate the citric acid cycle, so it will be able to maintain that high level of activity

Question 2

Aerobic respiration takes place in the ____ while anaerobic processes (like glycolysis) take place in the _____

Answer 2

Mitochondria

Cytosol

Question 3

The citric acid cycle takes place in the _____

Answer 3

Mitochondrial matrix

Question 4

The electron transport chain takes place in the ____

Answer 4

Inner mitochondrial membrane

Question 5

The electron transport chain generates ATP through the _____ and not the movement of electrons

Answer 5

Proton gradient

Question 6

___ is the final acceptor in the ETC

Answer 6

Oxygen

Question 7

This pathway is the most common way to form acetyl-CoA

Answer 7

Glycolysis

Question 8

Besides through glycolysis, acetyl-CoA can be formed in these four ways:

Answer 8

FA oxidation (beta oxidation)
AA catabolism
Ketones
Alcohol (although alcohol can inhibit the Krebs cycle, so it normally forms FA’s)

Question 9

The citric acid cycle yields: __ CO2, __CoA-SH, __ NADH, __H+, __ FADH and __ GTP

Answer 9

2 CO2, 1CoA-SH, 3 NADH, 3H+, 1 FADH, 1 GTP (that really becomes ATP)

Question 10

Including glycolysis and oxidative phosphorylation, a cell makes an average of __ to __ ATP

Answer 10

30-32 ATP

Question 11

This control point of the citric acid cycle is allosterically inhibited by ATP, citrate, NADH, and succinate

Answer 11

Citrate synthase

If there are already many products of the citric acid cycle, more doesn’t need to be produced so the cycle will be stopped before citrate can even form

Question 12

This control point of the citric acid cycle is inhibited by ATP and NAD+ but activated by ADP and NADH

Answer 12

Isocitrate dehydrogenase

This step is where the first NADH forms, so it makes sense that energy products would be analyzed here to see if more energy is needed or not

Question 13

This control point of the citric acid cycle is inhibited by ATP, NADH and succinylcholine-CoA and activated by ADP and calcium

Answer 13

alpha-ketoglutarate dehydrogenase

This step is also where NADH forms, so the cell wouldn’t want there to be too much or too little energy

Question 14

This complex is the only one that doesn’t contribute to the proton motive force. FAD is reduced to FADH2, and CoQ once again becomes CoQH2

Answer 14

Complex 2

Question 15

This complex sees NADH transfer an electron to CoQ, turning it into CoQH2. NADH also becomes NAD+

Answer 15

Complex 1

Question 16

This complex sees CoQ transform into cytochrome c

Answer 16

Complex 3

Question 17

This complex sees cytochrome c give an electron to oxygen. Water is also formed

Answer 17

Complex 4

Question 18

What is the general purpose of oxidative phosphorylation?

Answer 18

To utilize the energy created from the ETC proton gradient to phosphorylate ADP into ATP

Question 19

Compare and contrast chemiosmotic coupling and conformational coupling

Answer 19

Both say that ATP is produced from ADP

Chemiosmotic coupling says that ATP production is direct, in that the energy from F0 is used to directly phosphorylate ADP

Conformational coupling says that ADP phosphorylation is indirect and ATP is released due to a conformational change in the energy gradient

Question 20

Utilized in chemiosmotic coupling, this sector spans the membrane and acts like an ion channel, allowing protons to travel through and back to their gradient. It can then harness that energy to turn ADP into ATP

Answer 20

F0

Question 21

Utilized in chemiosmotic coupling, this sector is the portion of ATP synthetase that carries out the phosphorylation of ADP

Answer 21

F1

Question 22

___ and ___ are regulators of oxidative phosphorylation

Answer 22

O2 and ADP

Low levels of O2 lead to increased levels of FADh and NADH2, which inhibit the Krebs cycle

High levels of ADP lead to more ATP production