Lecture 33

Question 1

What are the two main parts of ATP Synthase?

Answer 1

F0-integral (transmembrane) protein part

F1-knobby parts that sticks into the mitochondrial Matrix

Question 2

What the the two parts of the ATP synthase Functionally?

Answer 2

• Rotor

- Stator

Question 3

Rotor

Answer 3

• comprised of c subunits (10 to 14 of them),E subunit, and Y subunit
• all of these subunits rotate together when protons move one at a time form the P side to the N side

Question 4

Stator

Answer 4

• comprised of a subunit, b2 subunits, S subunit, hexameter of a a B subunits
• entire complex is fixed in the membrane and cannot rotate with the rotor

Question 5

How does ATP synthase Work?

Binding Change Mechanism

Answer 5

• The c subunit complex rotates in the membrane as H+ move from the P to the N side of the inner membrane
• the y subunit of the rotor rotates with the c subunits and the y subunits stick into the center of the hexameter complex made up of the a-B pairs
• The y subunit is asymmetric and as it rotates pas a B subnit of each a-b pair, it induces a change in the B conformation

-depending on the position of the Y subunit, the B subunit is sequentially in open, loose and tight conformations

Question 6

Open conformation

Answer 6

Dissociate ATP and allow association of ADP and Pi

Question 7

Loose conformation

Answer 7

ADP and Pi bound and react

Question 8

Tight conformation

Answer 8

ATP bound

Question 9

What are some issues concerning transport of metabolites through the mitochondrion

Answer 9

• none of the molecules ADP, Pi, or ATP are freely diffusing through the inner membrane, so there needs to be a way to get ADP and Pi into the matrix and ATP out
• 2 NADH molecules are made in the cytoplasm from each glucose during glycolysis; NADH is not able to freely diffuse through the membrane, so there needs to be some way to get them into the matrix

Question 10

What are the two transporters that can fix the issue of getting ADP and Pi into the matrix and ATP out?

Answer 10

Adenine Nucleotide transporter

Pi Transporter

Question 11

Adenine nucleotide transporter

Answer 11

an antimport translocate that moves ADP3- into the matrix and ATP 4- out of the matrix

Question 12

Pi Transporter

Answer 12

Pi and H+ are moved together

-doesn’t change the amount of charge, but does change pH

Question 13

How do we move NADH into the matrix?

Answer 13

In the liver, heart, and Kidney a system called MALATE aspartate shuttle is used
-two antiports are involved
Malate/a-ketogluterate antiport
Asapartate/Glutamate antiport

Question 14

What are the two key reactions of the Malate aspartate shuttle

Answer 14

oxidation of malate to oxaloacetate in matrix

reduction of oxaloacetate to malate in the cytoplasm

Question 15

What is the result of the Malate aspartate shuttle?

Answer 15

the movement of one NADH equivalent from the cytoplasm into the matrix

Question 16

Glycerol Phosphate Shuttle

Answer 16

-second system for getting reducing equivalents into the matrix

Works by:

• NADH (from glycolysis) is oxidized by dihydroxyacetone phosphate to produce glycerol 3-phosphate in inter-membrane space
• Glycerol 3-phosphate on the inner membrane is oxidized and produces FADH2
• FADH2 in the membrane is oxidized to produce QH2 in the membrane
• QH2 feeds complex III

Question 17

What are the two dangers in the condition hypoxia

Answer 17

1) respiration cannot occur because of low pO2 and cells suffer ATP deficiency
2) Without high enough O2 in complex III, there is a accumulation of free radicals
- QH-; reacts with O2 to create a reactive oxygen species O2- which is extremely damaging to proteins and nucleic acids

Question 18

Reactive Oxygen species

Answer 18

O2 and OH (with dots in front of first letter)

Question 19

What are some mechanisms used to avoid the problems caused by Low pO2

Answer 19

1) Glycolysis increases, but entry of pyruvate into the citric acid cycle is inhibited, and ATP is produced anaerobically (by lactate Production)
2) reduction in the citric acid cycle reduces electron flow through oxidative phosphorylation
3) A more effective Cox 4-2 subunit (part of complex IV) is mobilized