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BIOCHEM 1 > ETC > Flashcards

ETC Flashcards

1
Q

define Substrate level Phosphorylation

A

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

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2
Q

Define high energy compounds with examples

A

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

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3
Q

energy released by Phosphoenolpyruvate

A

14.8 kcal/mol

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4
Q

energy released by 1,3-bisphoshoglycerate

A

11.8 kcal/mol

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5
Q

energy released by Creatine phosphate

A

10.3 kcal/mol

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6
Q

energy released by ATP

A

7.3 kcal/mol

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7
Q

SUBSTRATE LEVEL PHOSPHORYLATION IN SKELETAL MUSCLE

A

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

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8
Q

net ATP made by oxidative phosphorylation

A

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

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9
Q

SHUTTLE SYSTEMS FOR THE TRANSPORT OF NADH

A
  • Malate aspartate shuttle (malate shuttle)
  • Glycerol 3-phosphate shuttle - in muscle and brain
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10
Q

define ELECTRON TRANSPORT CHAIN

A

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

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11
Q

COMPLEX I

A

‘NADH dehydrogenase’
- read notes

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12
Q

where is the H+ pumped into

A

from matrix to intermembrane space

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13
Q

what is the e flow in NADH dehydrogenase?

A

NADH-FMN- FE-S -Q

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14
Q

role of ubiquinone

A

-mobile e carrier
- transfers equivalents from flavoproteins to cytochromes

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15
Q

complex 2

A

succinate dehydrogenase

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16
Q

e flow in succinate dehydrogenase

A

suc- FAD- FeS- CoQ

17
Q

complex iii and its e flow

A

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

18
Q

complex iv and its e flow

A

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

19
Q

what is the terminal e acceptor

A

oxygen

20
Q

at which complex water is formed and state the eq

A

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

21
Q

which complex directly recieves FADH2

A

complex II

22
Q

describe cytochrome

A

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

23
Q

content of each complex

A

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

24
Q

THE ETC MECHANISM

A

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

25
Q

How is ATP generated

A
  1. The inner membranes of the mitochondria contain ATP synthase.
  2. As H+ ions escape through channels into these proteins, the ATP synthase
    spins.
  3. 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
26
Q

OXIDATIVE PHOSPHORYLATION definition

A

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

27
Q

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

A

through ATP synthase

28
Q

where is ATP synthase located?

A

the inner mitochondrial membrane (IMM)

29
Q

ATP SYNTHASE

A

“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

30
Q

MECHANISM OF ATP SYNTHASE

A
  • Protons pass through F0 unit
  • Passing of proton, F1 unit become active
  • Activated F1 catalyzes phosphorylation of ADP and Pi and produces ATP
31
Q

CHEMIOSMOSIS

A

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

32
Q

CHEMIOSMOTIC HYPOTHESIS:
MITCHELL HYPOTHESIS (4)

A

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

33
Q

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

A

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

34
Q

describe Electron Transport inhibitors

A

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

35
Q

state inhibitors of each complex

A

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

36
Q

describe ATP synthase inhibitors

A

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

37
Q

describe uncouplers

A
  • 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
38
Q

state uncouplers

A

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

BIOCHEM 1 (21 decks)

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