The Electron Transport Chain

Question 1

explain how the electrons travel to the mitochondria

Answer 1

the reduced substrates donate E. Then E carriers pump out H+, and E flow to O2. The energy of E flow is stored as ECP energy. ATP synthase uses this energy to synthesize ATP

Question 2

what divides the matrix from the outer membrane?

Answer 2

a highly folded, protein rich inner membrane

Question 3

what is needed to transfer ADP and P into the mito?

Answer 3

transport proteins

Question 4

list the physical characteristics of the mito?

Answer 4

outer membrane, intermembrane space, inner membrane, cristae, matrix

Question 5

where are porins and what are its functions?

Answer 5

on the outer membrane, it permits free diffusion

Question 6

what can pass through the inner membrane freely?

Answer 6

CO2, H20, O2

Question 7

what needs transport proteins to move through the inner membrane?

Answer 7

ATP, ADP, P, CA2+, pyruvate

Question 8

where does ATP join onto the ATP-ADP translocator?

Answer 8

there is a positively charged cavity that binds ATP, note that inhibitors ( atractyloside, carboxyatractyloside)

Question 9

ATR and CATR can act where?

Answer 9

on the external surface of the inner membrane

Question 10

where does BA (bongkrekic acid) act?

Answer 10

only on the internal surface of the inner membrane

Question 11

the transfer of electrons from NADH to O2 releases how much energy?

Answer 11

2.5 ATP

Question 12

how are electrons passed into/onto the mitochondrial membrane?

Answer 12

there are E carries here that allow passage of E from complex I and II, via coenzyme Q to complex III, and then via cytochrome C to complex IV

Question 13

what is the shape of complex I? How does it transfer electrons?

Answer 13

it is L-shaped. It transfers E form NADH to CoQ via iron-sulfur clusters and sends 4 H+ to the intermembrane space.

Question 14

how does complex II work?

Answer 14

it transfers E from succinate to the CoQ

Question 15

how does complex III work?

Answer 15

the E are transferred to cytochrome C, and 4H+ for every 2 E transferred are sent to the intermembrane space. (by the Q cycle)

Question 16

how does complex IV work?

Answer 16

it accepts E from cytochrome C to reduce O2 to H20 and, sends 2 H+ for every 2 E transferred.

Question 17

what is the overall delta G of the reaction?

Answer 17

-218kJ/mol

Question 18

high values of E mean?

Answer 18

a strong tendency to be reduced

Question 19

complex I is inhibited by?

Answer 19

rotenone, amytal

Question 20

complex III is inhibited by?

Answer 20

antimycin A

Question 21

complex IV is inhibited by?

Answer 21

CN-

Question 22

explain the structures of complex I

Answer 22

it has a membrane arm, an series of iron sulfur complexes, and FMN that has 3 oxidation states. It has a peripheral arm in the matrix side

Question 23

what are the 3 oxidative states of FMN

Answer 23

FMN—fully oxidized (quinone)
FMNH— partially reduced (semiquinone)
FMNH2—fully reduced (hydroqinone)

Question 24

coenzyme Q also has 3 oxidative states name them

Answer 24

coQ–fully oxidized
QH+–semi reduced
QH2–fully reduced

Question 25

where is the transfer of the electron from complex I to coQ

Answer 25

at the N-2

Question 26

what happens when the electrons meet the peripheral arm?

Answer 26

there are conformational changes in it that induce conformational changes into the transmembrane arm that signal the opening of proton channels in the membrane. Allowing the passage of 4 H+ to the intermembrane space

Question 27

Complex II is also called

Answer 27

Succinate dehydrogenase or succinate-coenzyme Q oxireductase

Question 28

Where is complex II and how does it transport electrons

Answer 28

It is embedded in the mitochondrial membrane. It has a series of redox centers present, including a final heme-b cytochrome redox center. Electrons are released from succinate to coenzyme Q. Note that complex II also has FAD which delivers electrons to the iron sulfur clusters. Glycerol 3 phosphate delivers electrons to FAD (then they enter the intermembrane space.) It can also get electrons from the Electron Transporting Flavo Protein

Question 29

What are cytochromes. Name then and their general structures

Answer 29

They are electron transporting heme proteins .
Heme A : has isoprenoid units attached by an ethyl link, and a covalent hydrophilic bond with the membrane.
Heme C: is the same as A but has a covalent bond with a protein in the intermembrane
Heme B : is iron-protoporphyrin IX

Question 30

Read slide 36, 45, 47, 48

Answer 30

Dunno how to question it

Question 31

Complex III is also called

Answer 31

Coenzyme Q- cytochrome C oxireductase

Question 32

How does complex III work.

Answer 32

It takes electrons from coenzyme Q and send them to cytochrome C, it us redox centers like cytochrome and heme b/l. And it uses the Q cycle. Go to notes for explanation on Q cycle

Question 33

Explain the structure of cytochrome c

Answer 33

It has a central heme C group, surrounded by positively charged Lys residues. This ring of Lys residues is responsible for holding the heme C in place and helping it interact with the E bus

Question 34

Complex IV is also called. Explain its components

Answer 34

Cytochrome C oxireductase. It is copper A, B And heme A redox centers. The heme A and copper B are binuclear redox centers. This is where the O2 binding happens. Note that the redox center can only use 3 E

Question 35

How many O2 do we need to make a H20

Answer 35

2