Oxidative phosphorylation

Question 1

What characteristic of the inner mitochondrial membrane makes oxidative phosphorylation possible?

Answer 1

The tight membrane requires specific transporters that create the essential proton gradient

Question 2

What is oxidative phosphorylation?

Answer 2

The process used by the mitochondria to turn ADP and inorganic phosphate into ATP.

Question 3

What is the final electron acceptor in oxidative phosphorylation?

Answer 3

O2

Question 4

What are the first electron donors in oxidative phosphorylation?

Answer 4

NADH and FADH2

Question 5

Is the intermitochondrial membrane space acidic or basic?

Is the matrix of the mitochondria acidic or basic

Answer 5

Intermitochondrial membrane space: acidic

Matrix: basic

Question 6

Chemiosmosis

Answer 6

the movement of ions across a selectively permeable membrane, down their electrochemical gradient

Question 7

ATP synthase

Answer 7

The transporter that protons pass through down their chemical gradient to re-enter the mitochondrial matrix to be used for ATP synthesis

Question 8

Pathway of NADH through the electron transport chain

Answer 8

I -> Q -> III -> Cyt C -> IV

Question 9

Pathway of FADH2 through the electron transport chain

Answer 9

II -> Q -> III -> Cyt C -> IV

Question 10

4 electron carriers in the electron transport chain

Answer 10

1. NADH and FADH2
2. Ubiquinone (coenzyme Q)
3. Cytochromes (a,b,c)
4. Iron-Sulfur centre-containing proteins

Question 11

How many electrons does ubiquinone (coenzyme Q) accept? Lipid or water soluble?

Answer 11

One or two. Lipid soluble

Question 12

How many electrons does Cytochrome C accept? Lipid or water soluble?

Answer 12

Only one. Water soluble
(Because Cyt C only accepts one electron at a time, two molecules of Cyt C are needed when one NADH or one FADH2 enters the chain; reduced when entering Complex IV, oxidized when leaving Complex IV)

Question 13

[2 Fe - 2 S] clusters

Answer 13

two iron atoms joined by two atoms of inorganic sulfur. Use outer sulfurs to connect to cysteine residues in a protein. Can have several of these structures in one protein

Question 14

What is the purpose of Fe-S centres?

Answer 14

Allow for electrons to be passed many times through large proteins using redox reactions

Question 15

Which complex has a Cu-S center rather than a Fe-S center?

Answer 15

Complex IV

Question 16

What enzyme does Complex I use?

Answer 16

NADH dehydrogenase

Question 17

What enzyme does Complex II use?

Answer 17

Succinate dehydrogenase

Question 18

What enzyme does Complex III use?

Answer 18

Cytochrome C oxidoreductase

Question 19

What enzyme does Cytochrome C use?

Answer 19

None. Inter membrane space

Question 20

What enzyme does Complex IV use?

Answer 20

Cytochrome oxidase

Question 21

Which complexes use Fe-S centers?

Answer 21

Complex I, Complex II, and Complex III

Question 22

What reaction takes place in complex I?

Answer 22

NADH donates 2 electrons to reduce Q to QH2

Question 23

What reaction takes place in Complex II?

Answer 23

FADH2 is used to reduce Q to QH2

Question 24

Proton-motive force

Answer 24

Movement of protons during electron transfer creating an electrochemical gradient across a membrane

Question 25

2 components of electrochemical gradient

Answer 25

1. chemical potential- difference in proton concentration (pH gradient)
2. electrical potential- difference in electrical charge across the membrane (positive and negative charge creates a battery effect

Question 26

Conformational changes to beta subunits when gamma rotates

Answer 26

1. Beta ATP -> Beta empty
2. Beta ADP + Pi -> Beta ATP
3. Beta empty to Beta ADP + Pi

Question 27

Three conformations of Beta subunit

Answer 27

1. Beta empty (low affinity for ATP; very loosely binding)
2. Beta ADP +Pi (loosely binding)
3. Beta ATP (tightly binding)

Question 28

Where does oxidative phosphorylation take place?

Answer 28

The inner membrane of the mitochondria