Electron Transport Chain

Question 1

What is the overall mechanism of the electron transport chain

Answer 1

energy released from NADH and FADH2 is used to synthesize ATP

Question 2

Where does the electron transport chain occur

Answer 2

the mitochondria

Question 3

Oxidation of reduced factors: ___________

Answer 3

energetics

Question 4

Reduced cofactors are passed to oxygen ____________ along the electron transport chain

Answer 4

indirectly

Question 5

Instead of all energy being released at once, what occurs

Answer 5

the reoxidation of NADH and FADH2 is broken into several distinct processes
- results in smaller energy changes

Question 6

Electron carriers in ETC are arranged in order of…

Answer 6

increasing reduction potential

Question 7

What is the terminal electron acceptor

Answer 7

oxygen

Question 8

What is complex 1

Answer 8

NADH dehydrogenase

Question 9

What is complex 2

Answer 9

succinate dehydrogenase

Question 10

What is complex 3

Answer 10

acyl-CoA dehydrogenase

Question 11

What is complex 4

Answer 11

glycerol 3-phosphate

Question 12

What is another term for coenzyme Q

Answer 12

ubiquinone

Question 13

If ubiquinone accepts one electron what is formed

Answer 13

semiquinone radical

Question 14

If ubiquinone accepts two electrons what is formed

Answer 14

the alcohol ubiquonol

Question 15

How are electrons carried from one ETC complex to another

Answer 15

ubiquinol can freely move in the membrane, so it carries electrons from one complex to another

Question 16

Cytochrome C are a family of proteins with iron-containing ____________ prosthetic groups

Answer 16

heme

Question 17

Cytochrome C is a soluble protein found in the _______________ ____________

Answer 17

intermembrane space

Question 18

What is the function of cytochrome c

Answer 18

shuttles electrons from complex 3 to complex 4

Question 19

How many electrons does the heme group on cytochrome c carry at a time

Answer 19

one at a time

Question 20

Complex’s 1 and 2 transfer electrons to Q, reducing it to ________

Answer 20

QH2

Question 21

QH2 passes electrons to ____________________ through complex 3

Answer 21

cytochrome c

Question 22

Complex 4 transfers electrons from reduced cytochrome c to _______

Answer 22

O2

Question 23

Electron flow from complex’s 1,3,4 is accompanied by ____________ __________ from the matrix to intermembrane space

Answer 23

proton flow

Question 24

In the presence of an electron donor and O2, all carriers occurring before the point of obstruction become _____________ and the carriers beyond the point become ______________

Answer 24

before point; become reduced
after point; become oxidized

Question 25

Many of the carriers have distinctive optical ___________________ with different optical spectra under oxidized and reduced states

Answer 25

chromophores

Question 26

What is the importance of the optical chromophores

Answer 26

allows for identification of the redox state of carriers

Question 27

How many electrons from NADH are pumped

Answer 27

10 total 4 by complex 1, 4 by complex 3, and 2 by complex 4

Question 28

How many electrons from FADH2 are pumped

Answer 28

6 total 4 by complex 3 and 2 by complex 4 (bypass complex 1)

Question 29

What is the energy stored in the gradient called

Answer 29

the proton motive force

Question 30

What are the 2 components of the proton motive force

Answer 30

1. chemical potential energy 2. electrical potential energy

Question 31

What causes the chemical potential energy in proton motive force

Answer 31

difference in H+ concentration

Question 32

What causes the electrical potential energy in proton motive force

Answer 32

separation of charges

Question 33

Energy is _____________ in the proton gradient

Answer 33

conserved

Question 34

What is chemiosmotic theory

Answer 34

free energy liberated by redox reactions is used by ETC to pump proteins, moving H+ from matrix to intermembrane space - energy is stored as an electrochemical gradient protons flow back into the matrix passively down its concentration gradient through the proton pore of ATP synthase enzyme

Question 35

The energy of electrochemical gradient is released as is used for the generation of ATP by the ________ _________________ enzyme

Answer 35

ATP synthase

Question 36

ETC and ATP synthase are _____________

Answer 36

coupled

Question 37

Chemiosmotic theory readily explains the ______________ between ETC and ATP synthase

Answer 37

coupling

Question 38

If ETC is blocked, can ATP synthase function?

Answer 38

no and vice versa

Question 39

___________ _________________ is an obligatory part of the catalytic cycle

Answer 39

proton translocation

Question 40

How does the ETC/ATP synthase system become uncoupled

Answer 40

if the integrity of the inner mitochondrial membrane is disrupted, the proton gradient is eliminated - ETC continues, but ATP synthase stops *no longer coupled

Question 41

What is an example of a chemical that acts as an uncoupler

Answer 41

dinitrophenol (DNP)

Question 42

When DNP is added to the cell, what continues and what stops

Answer 42

ETC continues ATP synthase stops

Question 43

What is the mechanism of 2,4 DNP

Answer 43

- the DNP- picks up a proton to form DNPH - releases the H+ in the matrix forming DNP- - DNP- crosses back into intermembrane space and negative charge is delocalized over aromatic ring; structure is hydrophobic - proton gradient is collapsed - since energy is not conserved by ATP formation, it dissipates as heat