chapter 20

Question 1

what is the purpose of the electron transport chain

Answer 1

to capture high energy electrons to synthesize ATP

Question 2

what occurs in the electron transport chain

Answer 2

the flow of electrons from NADH and FADH2 to O2

Question 3

what does the electron transport chain consist of

Answer 3

exergonic oxidation-reduction reactions that generate a proton gradient

Question 4

what makes up cellular respiration

Answer 4

citric acid cycle and oxidative phosphorylation (ETC)

Question 5

where does the electron transport chain and ATP synthesis occur

Answer 5

in the mitochondria specifically on the inner membrane

Question 6

where does the citric acid cycle and fatty acid oxidation take place

Answer 6

in the mitochondrial matrix

Question 7

the outer mitochondrial membrane is permeable to

Answer 7

most small ions and molecules

Question 8

what channel protein enables the outer mitochondrial membrane to be permeable

Answer 8

mitochondrial porin

Question 9

the inner mitochondrial membrane is permeable to

Answer 9

almost nothing!!! trick question

Question 10

what are the folds on the inner mitochondrial membrane called

Answer 10

cristae

Question 11

the reduction potential (Eo’) or redox potential is a measure of

Answer 11

a molecule’s tendency to donate or accept electrons

Question 12

a strong reducing agent readily…..

Answer 12

donates electrons and has a negative reduction potential

Question 13

a strong oxidizing agent readily…..

Answer 13

accepts electrons and has a positive reduction potential

Question 14

what are the names of the 3 large complexes that pump proteins out of the mitochondria generating a proton gradient

Answer 14

NADH-Q oxidoreductase (complex 1)
Q-cytochrome c oxidoreductase (complex 3)
cytochrome c oxidase (complex 4)

Question 15

what type of molecule are the 3 large complexes

Answer 15

proton pumps

Question 16

what is complex 2

Answer 16

succinate-Q reductase

Question 17

what does complex 2 do

Answer 17

delivers electrons from FADH2 to complex 3

Question 18

is succinate-q reductase (complex 2) a proton pump

Answer 18

NO NO NO NO

Question 19

what does coenzyme Q do

Answer 19

-derived from isoprene
-binds protons (QH2) as well as electrons and can exist in several oxidation states

Question 20

what is the Q pool

Answer 20

oxidized and reduced Q molecules that are present in the inner mitochondrial membrane

Question 21

what is cytochrome C

Answer 21

an electron carrier that employs an iron incorporated into heme

Question 22

what does cytochrome C do

Answer 22

carries electrons from complex 3 to complex 4

Question 23

in general, what are cytochromes

Answer 23

electron-transferring proteins that contain a heme prosthetic group

Question 24

what does the heme iron cycle do

Answer 24

cycles Fe2+ and Fe3+ as it accepts or donates electrons

Question 25

what are iron-sulfur proteins

Answer 25

-also called nonheme iron proteins
-are prominent electron carries
-contain various types of iron-sulfur clusters

Question 26

what is the difference between iron-sulfur proteins and cytochrome c

Answer 26

cytochrome c and cytochromes in general contain heme to cycle iron while iron-sulfur proteins do not contain heme

Question 27

what is similar about iron-sulfur proteins and cytochromes

Answer 27

they both cycle iron to carry electrons

Question 28

how do high potential electrons of NADH enter the ETC

Answer 28

electrons from NADH are passed along to Q to form QH2 by complex I

Question 29

what happens after complex I receive the electrons from NADH

Answer 29

QH2 leaves the enzyme for the Q pool in the hydrophobic interior of the inner mitochondrial membrane

Question 30

what are the electron carriers that pass the electrons from NADH to Q

Answer 30

flavin mononucleotide (FMN) and several iron-sulfur proteins

Question 31

how many protons are pumped out of the mitochondria by complex I

Answer 31

FOUR

Question 32

what is the entry point for electrons from FADH2 of flavoproteins

Answer 32

ubiquinol

Question 33

what happens at complex 2

Answer 33

the FADH2 generated in the citric acid cycle reduces Q to QH2 and that then enters the Q pool

Question 34

what happens at complex 3

Answer 34

electrons from QH2 are used to reduce two molecules of cytochrome c in a reaction catalyzed by complex 3

Question 35

what two cytochromes are present at complex 3

Answer 35

b and c1

Question 36

how are electrons transferred from QH2 to cytochrome C

Answer 36

this process is called the Q cycle

Question 37

what happens in the Q cycle

Answer 37

first half: one electron from QH2 reduces cytochrome c and one reacts with Q to form Q.-
second half: another QH2 reduces cytochrome c and Q.-

Question 38

what is the result of the Q cycle

Answer 38

4 protons are pumped out of the mitochondria and two more are removed from the matrix

Question 39

what happens at complex 4 (general)

Answer 39

complex 4 accepts four electrons from four molecules of cytochrome c in order to catalyze the reduction of O2 to two molecules of water

Question 40

what happens in the cytochrome c oxidase reaction

Answer 40

eight protons are removed from the matrix

four protons, called chemical protons are used to reduce oxygen

four protons are pumped into the intermembrane space

Question 41

what are ROS

Answer 41

partial reduction of O2 generates highly reactive oxygen derivatives (ROS)

ROS are implicated in many pathological conditions

ROS include superoxide ions, peroxide ions, hydroxyl radicals

Question 42

what can help protect against ROS damage

Answer 42

superoxide dismutase (SOD)