Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochem > ATP Generation > Flashcards

ATP Generation Flashcards

1
Q

the main source of energy for ATP synthesis in oxygen dependent tissues

A

oxidation of acetyle CoA in the tricarboxylic acid cycle and the accompanying oxidation of reduced coenzyme products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what does Pyruvate Dehydrogenase do?

A

Pyruvate -> Acetyl CoA

and generates NADH & CO2 in the process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

advantages of a multienzyme complex

A

increase rxn rate & minimize side rxns

enables efficient transfer of intermediates between its different active sites
preventing loss of intermediates to other processes (they are usually covalently linked to the enzyme)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

E1 of PDH

A

E1 decarboxylase
requires the catalytic coenzyme prosthetic grp:
TPP thiamin pyrophosphate (vit B1)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

E2 of PDH

A

E2: dihydrolipoyl transacetylase
- transfers acetyl group to CoA
Lipoamide (catalytic coenzyme)

swinging arm to transfer electrons from E1 to E3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

E3 of PDH

A

E3: dihydrolipoyl dehydrogenase
- regenerates the oxidized form of lipoamide(E3)
FAD (flavin adenine dinucleotide)
uses NAD+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what inhibits PDH? how?

A

Arsenite
reacts w the two thiol groups of reduced lipoamide, preventing reconversion to oxidized (s-s) form, therefore inhibiting its function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

in the case of PDH deficiency, why is lactiacidemia expected?

A

pyruvate can be converted into lactate by the action of lactate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

inhibition of pyruvate dehydrogenase

A

products down regulate:
NADH (E3)
acetyl CoA (E2)
*both are comp inhibitors

most imp control: covalent inhibition:
P’lation of E1 serine residue
- the kinase that does this is stimulated by ATP/NADH/acetyle CoA and inhibited by pyruvate

*the PDH kinase and phosphatase are physically associated w/ PDH supramolecular complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

activation of pyruvate dehyrogenase

A

substrates up-regulate:
Ca2+
Insulin - activates the phosphatase
turn off the kinase (release the covalent inhibition) - ADP & Pyruvate

(up-regulation in response to low energy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

catalytic cofactors used by PDH

A

coenzyme prosthetic groups:
TPP (E1)
lipoamide (E2)
FAD (E3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

stoichiometric cofactors used by PDH

A

co-enzyme substrates:
CoA (E2)
NAD+ (E3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

overview of the mitochondiral ETC

A

4 enzymes in the inner membrane
-co-localization brings redox centers together
Electron flow driving by redox potential of components (most neg to most pos)
Enzymes use coenzymes as electron carriers (flavins, iron sulfur centers, heme)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

mitochondrial membrane phospholipid important in ETC organization

A

cardiolipin

deficit in cardiolipin synthesis leads to ETC dysfunction and mito-based disease (Barth syndrome; myopathy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

cytochrome c location and key features

A

tethered to the outside of the inner membrane by cardiolipin -> located in the space bet the two mito membranes
unique bc it is soluble
its location gives it considerable mobility -> interacts with Complexes III & IV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does PDH fit in with the TCA?

A

It is not part of the tricarboxylic acid cycle
Closely linked in terms if mito location and function
Reaction is a critical control point in utilization of pyruvate in the TCA cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Location of TCA enzymes?

Location of ETC enzymes?

A

TCA - mitochondrial matrix
(expt succinate dehydrogenase - inner mito membrane)
ETC - inner mitochondrial membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Initiating rxn of the TCA

A

Citrate Synthesis
condensation of Acetyl CoA + OAA -> Citrate

Irreversible due to hydrolysis of the thioester bond of Acetyl CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Aconitase

A

dehydrase/hydrase

removes H2O and adds it back, resulting in different location of the OH to prepare it for Isocitrate Dehydrogenase (IDH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

The ox-red rxns of the TCA:

A

4 ox-red rxns of the TCA:
3 - NAD reduction
1 - FAD reduction (succinate dehydrogenase)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

the specific intermediates of the TCA that lead to generation of ATP via oxidative phosphorylation via ETC

A

FADH2

NADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Isocitrate dehydrogenase

Alpha-ketoglutarate dehydrogenase

A

Produce CO2 expired (along w/ PDH)

Alpha-ketoglutarate is analagous to PDH
in structure/function, E3 is same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

substrate level phosphorylation of the TCA

A

Alpha-ketoglutarate DH
Succinyl thiokinase

Generates GTP from succinyl CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Succinyl thiokinase

A

aka Succinyl CoA synthetase
Ex of energy coupling where common intermediate can be found bound to the enzyme
thioester bond is high energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

In the TCA; CO2 is generated by

A

(PDH - not really part of the TCA)
Isocitrate dehydrogenase
Alpha-ketoglutarate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

In the TCA; NADH is generated by

A

Isocitrate DH
Alpha-ketoglutarate DH
Malate DH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

In the TCA; FADH2 is generated by

A

Succinate DH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

In the TCA; GTP is generated by

A

Succinyl thiokinase

via the hydrolysis of the thioester bond of Succinyl CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Overall the TCA is ___ & ___ , and operates under Anaerobic/Aerobic conditions.

A

exergonic & irreversible

aerobic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

The three irreversible steps of the TCA

A

Citrate synthase
Isocitrate DH
Alpha-ketoglutarate DH

prevent cycle from reversing direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Irreversibility may be the result of

A

highly negative delta G

hydrolytic bond cleavage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Regulation of Citrate synthase

A

inhibited by citrate

no allosteric regulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Regulation of Isocitrate DH

A

Inhibited allosterically by:
NADH
ATP

Activated by
ADP (major)
Ca2+

Primary site of control.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Regulation of Alpha-ketoglutarate DH

A 
Activated by Ca2+
Inhibited by:
NADH
Succinyl CoA (product)
GTP (product)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

TCA as source of metabolic substrates:

Citrate ->

A

Fatty acid and Sterol synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

TCA as source of metabolic substrates:

alpha-ketoglutarate ->

A

Amino acid synthesis -> Neurotransmitters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

TCA as source of metabolic substrates:

Succinyl CoA ->

A

Heme synthesis

38
Q

TCA as source of metabolic substrates:

Malate ->

A

Gluconeogenesis

39
Q

TCA as source of metabolic substrates:

Oxaloacetate ->

A

Amino acid synthesis

40
Q

What drives electron flow? How does this apply to the ETC carriers?

A

Redox potential of the components; most negative to most positive
Lower affinity complex (-E) to Higher affinity complexes (+E)
Concentrations of components allows fine tuning of flow

41
Q

Protons are pumped across ___ to ___ forming an ____

A

the inner mitochondrial membrane
the intermembrane
electrochemical gradient

42
Q

positive redox potential vs. negative redox potential in terms of affinity for electrons

A

positive - higher affinity
negative - lower affinity
(than a proton)

43
Q

delta G =

A

-nFdeltaE

positive reduction potential => favorable delta G

n = # of electrons
F = Faraday constant - energy produced by an electron in a 1volt potential
44
Q

ETC - Location of:
Protein Complexes
CoQ
Cytochrome C

A

Protein Complexes - intimately assoc w the membrane
CoQ - in the lipid core
Cytochrome C - intermembrane space

45
Q

Proton Pump Complexes

A

I, III, IV

46
Q

NAD vs NADP

A 
NADH:
source of electrons from TCA and PDH
functions in ox rxns of catabolism
most abundant ox-red system in cell
cosub coenz for Complex I

NADP:
functions in reductive synthesis
has a phosphate grp (only structural diff)

Both NAD & NADP:
accept 2 electrons and a proton in a form similar to a H- (hydride ion)
weak oxidants
exist free in cell
behave as true co-enzyme co-substrates (bc are weakly bound to enzymes)

47
Q

Complex I

A

NADH - ubiquinone oxidoreductase

NADH (substrate) electrons are passed to
FMN (the flavoprotein prosthetic group) then to Ubiquinone via series of FeS centers
4 H+ are pumped

48
Q

Complex II

A

Succinate - ubiquinon oxidoreductase, a flavoprotein

Electron flow: succinate via FAD and FeS to Ubiquinone
no H+ are pumped

49
Q

Which one exists primarily in its reduced form, NADH or NADPH?

A

NADPH (functions in reductive synthesis)

remember NAD is involved in oxidative phosphorylations so you want it in its oxidized form

50
Q

Flavin nucleotides

A

tightly bound coenzyme prosthetic grps
1 or 2 electron transfers
semiquinone intermediates are relatively stable
in ETC do not react w O2 directly; are reox by other components of chain
Complex I

51
Q

Iron sulfur prosthetic groups

A

most abundant redox cofactors of ETC
Complexes I,II, III
contain equal amts non-heme iron & sulfide
single electron carriers

52
Q

Ubiquinone (coenzyme Q)

A

passes electrons from Complexes I & II to III
ubiquinol = reduced ubiquinone
lives in the hydrophobic lipid core of the mem -> freely diffusable
1 or 2 electron transfers

53
Q

Complex III

A

Ubiquinone- cytochrome c oxidoreductase

3 prosthetic groups that = redox centers:
cytochrome b, cytochrome c1, Fe-S protein

Electron flow: UQH2 (ubiquinol) is oxidize as 2 cytochromes are reduced
Electron path is called the Q cycle (within Complex III)

54
Q

use heme prosthetic groups as electron carriers

A

Complexes III and IV

Cytochrome C

55
Q

hemes of the ETC

A

the cytochromes
a/b/c - based on the structure of the heme
same heme as hemoglobin
1 electron transfers
do not bind O2 -> site occupied by aa side chain (exception; cytochrome a3 - last cytochrome of chain, binds O2 and is ox as a result, binuclear center w Cu in Complex IV)

56
Q

Complex IV

A

contains antibody fragment for crystallization

Electron Flow: Cyt c -> Cu (a) (subunit II) -> binuclear center (cyto a3 and Cu b) where O2 is reduced to H2O
4 protons pumped

net: 2 H+ released to cytosol for every 4 taken up from the matrix
ROS forms by incomplete red of O2

57
Q

cytochrome a3

A

Complex IV
last cytochrome of chain
Special; binds O2 and is ox as a result, binuclear center w Cu

58
Q

overview of electron flow in Complex I

A

NADH -> FMN -> FeS -> CoQ

59
Q

overview of electron flow in Complex II

A

FADH2 -> FeS -> CoQ

60
Q

overview of electron flow in CoQ

A

CoQH2 -> cytochrome c via Complex III

req ISP, cyto c1, cyto b

61
Q

overview of electron flow in Cytochrome C

A

Fe2+ -> Cu a of Complex IV

62
Q

overview of electron flow in Complex IV

A

from Cu a -> cyto a1 -> cyto a3-Cub binuclear center -> O2 => water

63
Q

how many electrons are required to reduce O2 to H2O?

A

4

64
Q

superoxide dismutase rxn

A

2O2- -> H2O2

65
Q

catalase rxn

A

H2O2 -> 2H2O + O2

66
Q

Complexes of the ETC that pump electrons

A

Complexes I, III, IV

due to great enough energy diff bet donor of elec and receiver
Complex II doesnt pump bc not enough energy

67
Q

Oxidative phosphorylation

A

ATP synthesis linked to ETC and O2 reduction
the proton gradient drives synthesis instead of P’lated intermediates donate electrons
O2 consumption dependent on ADP availability

68
Q

Relative pH; Matrix, Intermembrane space, Cytosol

A

Intermembrane Space equivalent to Cytosol
Matrix - more basic (bc pumping H out)

= Chemiosmotic Hypothesis - proton-motive force drives ATP synthase

69
Q

Chemiosmotic Hypo Rational

A
  1. no chemical intermediates
  2. proton gradient = primary energy source for ATP synthesis
  3. one directional proton pumps exists for producing and using said electrochem gradient (anisotropically oriented)
70
Q

ATP synthase

A

is an ATPase as well

F1 - produces ATP, alpha3 beta3 dont rotate
beta binds ADP - O=open state, L=loose stabilizes ADP - P, T=tight ATP formed
Fo - protons spin the c ring
gamma subunit - rotar, not symmetric

71
Q

Respiratory control

A

rate of respiration determined by the rate of ATP synthesis

ATP synthesis limited by availability of ADP or Pi

72
Q

Reduction potential difference required for ATP synthesis

A

0.3 V

only Complexes I, III, IV

73
Q

How many protons per 1 ATP synthesized

A

3H+

74
Q

Reversal of the ATP-linked pump

A

when ATP levels in mito drop
decrease, then reversal of the proton-pumping by the F1Fo ATPase
reversal -> ATP synthesis

75
Q

Oxphos; Respiratory chain inhibitors

A

block electron transport

CN, CO

76
Q

Oxphos: Phosphorylation ihibitors

A

inhibit the F1Fo ATPase

Oligomycin - prevents mvmt of protons through ATP synthase => reduced O2 consumption

77
Q

Osphos:Uncouplers

A

allow protons to leak, depletes gradient, need to make more gradient so O2 consumption increases

Dinitrophenol:
uncouples ATP syn and proton pump, equilibriates pH across inner mem

UCP1 / thermogenin:
brown adipose, mem spanning protein, allows Hs to enter mito w/o ATP formation -> heat generation
(short-circuits proton battery of mito)

78
Q

electrogenic transporters

A

affected by the membrane potential
so requires the proton gradient
ex. Ca2+ uniport uptake, ATP/ADP exchange

79
Q

how is ADP taken into the mito, and ATP released?

A

electrogenic antiporter
1:1
homodimer but 1 binding site -> alternates how it faces (matrix/intermem)
pH gradient drives ATP out ADP in

80
Q

how is Ca2+ taken into the mito?

A

electrogenic uniporter
dependent on proton gradient
high conc -> pore formation, cyto c release, and apoptosis

81
Q

how is phosphate taken into the mito?

A 
phosphate translocase (electrogenic symporter)
1 H : 1 Pi
82
Q

Malate-Aspartate Shuttle

A 
transport shuttle for NADH -> get electrons into mito via NADH
req; 2 carriers, 4 enzymes
alpha-ketoglutarate -> OAA
Malate
Aspartate -> Glutamate
83
Q

Oligomycin

Dinitrophenol

A

reflect coupling of O2 consumption w ATP synthesis

84
Q

Dinitrophenol:

A

Uncoupler
uncouples ATP syn and proton pump, equilibriates pH across inner mem by freely crossing the membrane
hydrophobic weak acid

85
Q

UCP1 / thermogenin:

A

Uncoupler
brown adipose, mem spanning protein, allows Hs to enter mito w/o ATP formation -> heat generation
(short-circuits proton battery of mito)

86
Q

Ancillary energy-coupled reactions of mitochondria

A

do not req ATP but consume energy using the proton gradient
relieve resp control and stimulates e transport
inhibited by respiratory inhibitors & uncouplers
unaffected by phosphorlyation inhibitors
ex:
-Ca uptake, upregs PDH, uniporter
-ATP & Aspartate transport to cytosol, reduces pH gradient
-Energy coupled transhydrogenation (need NADPH to keep glutathione in its functional reduced state GSH)

87
Q

Leber’s Hereditary Optic neuropathy

A

lowered activity Complex I due to single bp mutation in 3 mitochondrial disease

88
Q

Esercise intolerance

A

mutations in cyt b of complex III
not maternally inheritied
mutations seem somatic in muscle tissue

89
Q

Mitchondria and Apoptosis

A

Pore formation -> release of cyto c
cyto c complexes with pro-apoptotic factors (Apaf1) & protease precursors (pro-caspase 9) = Apoptosome
Apoptosome -> act of caspases

Pore formation & protein loss => Bioenergetic Crisis = inability to produce ATP, prelude to apoptosis

90
Q

Parkinson’s disease

A

mito ETC dysfuntion, including Complex I, increasinly viewed as having an important link

Biochem (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions