ETC

Question 1

define Substrate level Phosphorylation

Answer 1

Phosphorylation or high energy phosphate bond
formation occurs at substrate level
* It produces ATP directly

Question 2

Define high energy compounds with examples

Answer 2

Substances that release energy higher than ATP
Phosphoenolpyruvate – 14.8 kcal/mol
 1,3-bisphoshoglycerate – 11.8 kcal/mol
 Creatine phosphate – 10.3 kcal/mol
 ATP – 7.3 kcal/mol

Question 3

energy released by Phosphoenolpyruvate

Answer 3

14.8 kcal/mol

Question 4

energy released by 1,3-bisphoshoglycerate

Answer 4

11.8 kcal/mol

Question 5

energy released by Creatine phosphate

Answer 5

10.3 kcal/mol

Question 6

energy released by ATP

Answer 6

7.3 kcal/mol

Question 7

SUBSTRATE LEVEL PHOSPHORYLATION IN SKELETAL MUSCLE

Answer 7

Creatine Phosphate- “energy rich” phosphate is formed from ATP in muscle
- can regenerate ATP as needed

Question 8

net ATP made by oxidative phosphorylation

Answer 8

glycolysis- 6 ATP from 2 NADH
transition reaction- 6 ATP from 2 NADH
krebs cycle- 18 ATP from 6 NADH & 4 ATP from 2FADH2
total= 34 ATP

Question 9

SHUTTLE SYSTEMS FOR THE TRANSPORT OF NADH

Answer 9

• Malate aspartate shuttle (malate shuttle)
• Glycerol 3-phosphate shuttle - in muscle and brain

Question 10

define ELECTRON TRANSPORT CHAIN

Answer 10

Is the transfer of electrons from NADH and FADH2 to oxygen through series of e transporter on the inner mitochondria membrane
The electron derived combine with O2 and
the energy released from these oxidation-reduction process is used to drive the synthesis of ATP from ADP

Question 11

COMPLEX I

Answer 11

‘NADH dehydrogenase’
- read notes

Question 12

where is the H+ pumped into

Answer 12

from matrix to intermembrane space

Question 13

what is the e flow in NADH dehydrogenase?

Answer 13

NADH-FMN- FE-S -Q

Question 14

role of ubiquinone

Answer 14

-mobile e carrier
- transfers equivalents from flavoproteins to cytochromes

Question 15

complex 2

Answer 15

succinate dehydrogenase

Question 16

e flow in succinate dehydrogenase

Answer 16

suc- FAD- FeS- CoQ

Question 17

complex iii and its e flow

Answer 17

cytochrome b-c1
CoQ —> Cyt b —> Cyt c1 —-> Cyt c

Question 18

complex iv and its e flow

Answer 18

cytochrome C oxidase
cyt.c- cyt.a-a3 -O2

Question 19

what is the terminal e acceptor

Answer 19

oxygen

Question 20

at which complex water is formed and state the eq

Answer 20

cytochrome C oxidase
4H+ + 4e+ O2= 2H2O + ENERGY

Question 21

which complex directly recieves FADH2

Answer 21

complex II

Question 22

describe cytochrome

Answer 22

protein with heme grp( porphyrin ring +iron)
reversible state of iron depending on electron
fe2+- ferrous
fe 3+- ferric

Question 23

content of each complex

Answer 23

I-FMN, FeS,Q,flavin prosthetic grp
II-FAD centre, FeS
III-heme grp ( porphyrin ring+ iron), FeS, Cyt b,Cyt c1
IV- cytochromes a+a3,Cu atoms,heme a & heme a3

Question 24

THE ETC MECHANISM

Answer 24

1.High-energy electrons from NADH and FADH2 are passed along the ETC from one carrier protein to the next.
2.During electron transport, H+ ions build up in the intermembrane space, so it is positively charged.The other side of the membrane, from which those H+ ions are taken, is now negatively charged.
3. At the end of the chain, an enzyme combines these electrons with H+ ion and O2 to form water.
4. The inner membranes of the mitochondria contain ATP synthase.
5. As H+ ions escape through channels into these proteins, the ATP synthase
spins.
6. As it rotates, the enzyme grabs a low-energy ADP, attaching a phosphate (Pi), forming high-energy ATP.
The energy for the pumping comes from the coupled oxidation- reduction reactions

Question 25

How is ATP generated

Answer 25

4. The inner membranes of the mitochondria contain ATP synthase. 5. As H+ ions escape through channels into these proteins, the ATP synthase spins. 6. As it rotates, the enzyme grabs a low-energy ADP, attaching a phosphate (Pi), forming high-energy ATP. The energy for the pumping comes from the coupled oxidation- reduction reactions

Question 26

OXIDATIVE PHOSPHORYLATION definition

Answer 26

Synthesis of ATP from ADP (phosphorylation) that occur when NADH and FADH2 are oxidized by ETC (oxidation) through H+ gradient.

Question 27

how do the protons in the intermembrane space enter the matrix?

Answer 27

through ATP synthase

Question 28

where is ATP synthase located?

Answer 28

the inner mitochondrial membrane (IMM)

Question 29

ATP SYNTHASE

Answer 29

“knob-and-stalk structure * F1(knob) contains the catalytic subunits for ATP production * F0 (stalk) has a proton channel which spans the membrane  Function: synthesize ATP from ADP and inorganic phosphate (Pi) that generated by the proton motive force of the ETC

Question 30

MECHANISM OF ATP SYNTHASE

Answer 30

* Protons pass through F0 unit * Passing of proton, F1 unit become active * Activated F1 catalyzes phosphorylation of ADP and Pi and produces ATP

Question 31

CHEMIOSMOSIS

Answer 31

the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration.

Question 32

CHEMIOSMOTIC HYPOTHESIS: MITCHELL HYPOTHESIS (4)

Answer 32

Free energy generated by the transfer of electrons by ETC is used to produce ATP from ADP and Pi. ETC is coupled to ADP phosphorylation by pumping of H+ across inner mitochondrial memb from matrix to space. Generation of electrical (H+) and chemical (pH) gradient across the inner mitochondrial membrane (IMM) Pumping of protons into the matrix through complex V

Question 33

P:O ratio Number of ATP made per O atom reduced

Answer 33

P/O for 1 NADH = 3:1 P/O for 1 FADH2 = 2:1

Question 34

describe Electron Transport inhibitors

Answer 34

Inhibit ETC and ATP synthesis (as they are coupled) * Site specific inhibitors * Prevent passage of electrons by binding to specific component of ETC * Block oxidation-reduction reaction

Question 35

state inhibitors of each complex

Answer 35

Complex I: Rotenone Complex II: Carboxin Complex III: Antimycin A Complex IV: , Sodium azide,Cyanide Carbon monoxide

Question 36

describe ATP synthase inhibitors

Answer 36

-Oligomycin: Binds to Fo and close the proton channel. -Atractyloside: Inhibits ATP-ADP exchange

Question 37

describe uncouplers

Answer 37

- compounds that form channels for H+ to re-enter mitochindrial matrix without energy being captured as ATP - energy is released as heat( non-shivering thermogenesis) - oxidation is uncoupled from phosphorylation becoz energy cannot be trapped as ATP

Question 38

state uncouplers

Answer 38

1.Thermogenin (natural) – brown adipocytes (mammals) - 90% of energy produced during ETC dissipated as heat to maintain body temp in infants 2. 2,4-dinitrophenol (2,4-DNP) -synthetic uncoupler - H+ carrier that readily diffuses through mitochondrial membrane 3. High dose of aspirin, salicylates