Oxidative phosphorylation and the Electron Transport Chain

Question 1

what occurs in glycolysis

Answer 1

Pyruvate and 2 ATP molecules are generated per molecule of glucose as well as 2 molecules of NADH. Takes place in the cytoplasm of all cells and does not require oxygen

Question 2

what occurs in the TCA / Krebs cycle

Answer 2

Uses the pyruvate molecules from glycolysis to generate 2 ATP as well as several molecules of FADH2and NADH for the electron transport chain. Takes place in the mitochondrial matrix and requires oxygen.

Question 3

what occurs in Oxidative phosphorylation/the ETC

Answer 3

Uses the NADH and FADH2molecules formed during glycolysis and TCA, creates a proton gradient that ultimately leads to the production of about 34 molecules of ATP. Takes place in the mitochondrial matrix and requires oxygen.

Question 4

what by product molecules can be produced which can be oxidised to release further energy

Answer 4

NADH and FADH2

Question 5

how many of NADH and FADH 2 shuffle through the ETC

Answer 5

34 ATP = 10 NADH (3 ATP per NADH)
2 FADH2 (2 ATP per FADH2)

Question 6

what is NADH

Answer 6

Nicotinamide adenine dinucleotide
(NAD + Hydrogen) and is a co-enzyme found in all living cells

Question 7

what reaction is NADH involved in

Answer 7

NADH is usually involved in REDOX reactions as a transporter of electrons.
NAD+ is its oxidized form, NADH is the reduced coenzyme form (OIL RIG)

NAD+ (Oxidised state = can accept electrons!)

Question 8

What is FADH2

Answer 8

Flavin adenine dinucleotide, another important co-enzyme found in all living cells

Question 9

what does FADH2 transport

Answer 9

electrons
FAD is its oxidized form, (wants to accept electrons!)

FADH2 is the reduced coenzyme form (accepts two electrons and two protons)

Question 10

What reaction changes NAD+ to NADH

Answer 10

Redox reaction - NAD+ accepts 2 electrons causing it to be negatively charged

Then accepts a positively charged hydrogen ion (H+) from surrounding environment to give neutral NADH

Question 11

What reaction changes NAD+ to NADH

Answer 11

Redox reaction - NAD+ accepts 2 electrons causing it to be negatively charged

Then accepts a positively charged hydrogen ion (H+) from surrounding environment to give neutral NADH

Question 12

when is NADH produced

Answer 12

produced in glycolysis and Krebs cycle

Question 13

what 2 joined nucleotides does NADH have

Answer 13

adenine and nicotinamide

Question 14

where is FADH2 produced

Answer 14

produced in Krebs cycle

Question 15

What 2 joined nucleotides does FADH2 have

Answer 15

adenine and flavine mononucleotide

Question 16

what 2 closely connected components in the Oxidative Phosphorylation

Answer 16

the ETC and chemiosmosis

Question 17

what does NADH and FADH2 do in Oxidative Phosphorylation

Answer 17

transfer electrons to oxygen across several complexes in the electron transfer chain, being returned to their oxidised forms (NAD+ and FAD)

Question 18

why is oxygen important in Oxidative Phosphorylation

Answer 18

final acceptor of electrons and is reduced to H2O in the production of ATP

Question 19

where does oxidative phosphorylation occur

Answer 19

the mitochondrion

Question 20

how is a proton gradient H+ established

Answer 20

as a result of electron transport and redox potential

Question 21

what is redox potential

Answer 21

(E)– a measure of a substance’s affinity for electrons

Question 22

what 2 processes occur in Oxidative Phosphorylation

Answer 22

1- produces a proton concentration gradient by the respiratory ETC, a series of enzyme complexes embedded in the inner mitochondrial membrane, oxidises NADH and FADH2. Electrons are passed from the reduced coenzymes to O2.
2- The proton concentration gradient is a reservoir of free energy – protons are channelled back across the inner membrane through an enzyme complex, ATP synthase

Question 23

how are electrons transferred from NADH and FADH2 to oxygen along the ETC

Answer 23

using 4 multi-subunit large enzyme complexes (I, II, III, IV) and 2 mobile electron carriers (coenzyme Q and cytochrome c)

Question 24

what are redox reactions (exergonic or endogenic)

Answer 24

exergonic; the energy released is used to ‘pump’ protons across the inner mitochondrial membrane

Question 25

Are Electrons directly transferred from NADH or FADH2 to O2

Answer 25

no
Instead, NADH and FADH2 pass electrons to members of the ETC which are sequentially reduced then oxidised
O2 is the final acceptor of electrons

Question 26

what are small electron carriers

Answer 26

membrane proteins

Question 27

what is Chemiosmosis

Answer 27

is the movement of ions across a semipermeable membrane

Question 28

what occurs in complex 1

Answer 28

NADH dehydrogenase catalyses the transfer of electrons from NADH to coenzyme Q (CoQ)
Acts as a proton pump.

Question 29

what occurs in complex 2

Answer 29

succinate-CoQ oxidoreductase catalyses the transfer of electrons to coenzyme Q (CoQ)
and the product is fumarate + CoQH2.
CoQH2 is called ubiquinol, a reduced state of CoQ

Question 30

what is complex 3

Answer 30

When CoQH2 is re-oxidised to CoQ the H+ passes out the other side of the membrane (second reaction)

Question 31

what is the complex 4

Answer 31

cytochrome c oxidase, catalyses the transfer of electrons from cytochrome c to oxygen.
Completes the oxidation of original NADH molecule
Proton pumping also takes place (third reaction)

Question 32

How does proton pumping generate ATP molecules?

Answer 32

Oxidative phosphorylation couples the oxidation of NADH and FADH2 with the phosphorylation of ADP to generate ATP

Question 33

what is ATP Synthase

Answer 33

A multi-subunit protein - ATPase
This enzyme has a channel for protons to flow from the intermembrane space into the matrix.
Synthesis is in direct response to oxidation of NADH and FADH2

Question 34

how many moles of ATP does the complete oxidation of 1 molecule of glucose generates

Answer 34

38

Question 35

in cells using the glycerol phosphate shuffle what is the ATP yield

Answer 35

2- overall ATP yield in these cells is 36 per mole of glucose