Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BIOCH 310 > Oxidative phosphotylation > Flashcards

Oxidative phosphotylation Flashcards

(94 cards)

Start Studying
1
Q

What are the three types of electron transfer that occur in oxidative phosphorylation?

A

1) Direct transfer (no H+ move, only electrons)
-Fe3+ –> Fe2+

2) As a hydrogen atom
-reduction of coQ to FAD

3) As a hydride ion
-NADH to FMN in complex 1

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

why are the complexes in the ETC needed?

A

Because when groups are in contact the electrons transfer very fast

-the rate of transfer drops 10 fold for every 1.4 nanometer difference

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

what is the name of complex 1?

A

NADH-Ubiquinone oxidoreductase

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

what is the name of complex 2?

A

Succinate-ubiquinone oxidoreductase

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

what is the name of complex 3?

A

Ubiquinol-cytochrome C oxidoreductase

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

what is the name of complex 4?

A

Cytochrome C oxidase

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

what complex is also in the CAC?

A

complex 2 (succinate DH)

Succinate-ubiquinol oxidoreductase

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

how do FMN and FAD differ? how are they similar? where are they present in the ETC?

A

FMN is a riboflavin attached to a phosphate group
-in complex I

FAD contains FMN as a part of its structure, in addition to an AMP attached to the phosphate
- in complex II

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

What are flavoproteins? what nutrient are they derived from?

A

proteins that contain a nucleotide derivative of riboflavins as a prosthetic group

derived from Vit B2

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

how many electrons can flavins accept and pass on?

A

can accept 2 at a time and pass on 1

This is important as NADH and FADH2 release 2 electrons at complex I and II

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

how would you explain the reduction activity of Fe-S clusters? How does it differ from a Rieske Fe-S cluster?

A

the reduction potentials vary, with lower reduction potential at the beginning of the complex and higher potential towards the end

Rieske Fe-S clusters are attached to His groups rather than Cys groups and they have a higher affinity for electron pulling

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

How many oxidation and reductions can Fe-S clusters undergo (electron movement)?

A

they can only move ONE electron

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

how many classes of cytochromes are present in the mitochonria?

A

3

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

what peaks would you expect to observe in the reduced vs oxidized form of cytochrome C? what does the subscript beside the “Cty c” tell you?

A

1 major peak in oxidized form
1 major peak and 2 smaller peaks in the reduced form

the number in a subscript indicates the absorption peak

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

what factors contribute to the difference in reduction potential of cytochromes?

A

1) difference in structure of apoprotein

2) Difference in heme groups

3) difference in location within the complex

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

what are the majority cofactors in complex 1? how does this impact movement of electrons?

A

Fe-S clusters
-they can only pick up and move one electron at a time

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

why is it so important that FMN is the first cofactor in complex 1?

A

it can pick up 2 electrons but pass on 1

-minimizing electron leakage is essential to prevent formation of ROS

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

what complex are there no H+ pumped across? why?

A

Succinate-ubiquinol oxidoreductase (complex 2)

-there is not enough energy produced as electrons move through complex 2 for H+ to be moved across the membrane

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

how many electrons can cytochromes pick up and move?

A

pick up one, move one

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

when given delta G values for each complex, what does this tell us?

A

the delta G of each complex indicates the amount of energy released from the movement of electrons to pump protons across the membrane

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

when an inhibitor is present in the ETC, what will be reduced and what will be oxidized when?

A

prior to the inhibitor everything is reduced and after the inhibitor everything will be oxidized as oxygen pulls all the electrons towards it

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

where does Antimycin inhibit the ETC?

A

complex 3

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

where does CN- or CO inhibit the ETC?

A

the last point where electrons leave, inhibiting oxygen from accepting the electrons

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

what is the source of electrons for complex 2?

A

succinate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
why is FADH2 not an electron donor in the ETC?
FADH₂ is generated within Complex II and immediately transfers its electrons to ubiquinone (CoQ) as part of the ETC. It does not serve as an independent electron donor for Complex II because it is produced and used within the complex itself
26
where does movement of electrons vs protons occur in NADH ubiquinone oxidoreductase?
movement of electrons mainly in the hydrophilic part and movement of H+ mainly in the hydrophobic part
27
are there heme cofactors present in NADH ubiquinone oxidoreductase?
no, there are only Fe-S clusters it is a non-heme iron protein
28
how many H+ move for every pair of electrons at the NADH ubiquinone oxidoreductase?
4
29
explain the movement of electrons in the NADH ubiquinone oxidoreductase
electrons move from NADH to FAD which get picked up by each Fe-S cluster the last Fe-S cluster passes the electron to N2 which causes a conformational change that is transmitted from the Aq region to helixes along the membrane to the hydrophobic region changes in conformation of the helix regions cause it to think the residues are being charged which will change the pKa to pick up H+ and pass it on
30
what structure must cross a membrane?
alpha helix
31
why coQ able to move very easily within the inner mitochondrial membrane?
it is very hydrophobic due to the 50 isoprene side chains within Q10
32
how many electrons can coQ accept?
very flexible in its ability to pick up electrons, can pick up 1 or 2
33
what makes coQ a good antioxidant?
the flexibility for it to pick up electrons -1 or 2 electrons and doesn't need to pick up a H+ with it
34
is coQ a protein?
no, it is the only non-protein component of the ETC
35
where in complex 3 does antimycin bind?
at Qi, completely blocking the transfer of e- through complex 3
36
why does QH2 donate electrons to pick them back up again?
in order to pump protons across the IMS
37
explain the Q cycle in the ubiquinol cyt C oxidoreductase:
1) QH2 is reduced to Q and 2 e- are released -one e- goes to Fes then C1 where Cyt C is reduced and the e- is taken to complex 4 -the other e- is transferred from heme b (low affinity) to heme b (high affinity) 2) 2H+ are pumped from the matrix to the IMS 3) when Qi accepts the e-, Q is partially reduced 4) another QH2 is reduced and the e- follow the same path 5) the second e- that is taken to Qi converts the partially reduced Q to QH2 with the uptake of 2H+ 6) the oxidation of the second QH2 pumps 2 more H+ from the matrix to IMS, causing a total of 4H+ to be pumped
38
what is the overall rxn for the Q cycle?
39
what is the main function of cyt C? what is another main function it has in the body?
1) transfer e- from complex 3 to 4 2) apoptosis (programmed cell death) therefore, it is highly conserved
40
how many e- and H+ are needed to reduce an O2 molecule? how many H2O does this create?
4 e- and 4H+ produces 2 water molecules
41
how many H+ are pumped through Cyt C oxidase?
2
42
how many H+ are pumped for every 2 e- going through complex 4?
2H+ for every 2 e-
43
what is the purpose of heme b in succinate ubiquinone oxidoreductase?
prevents leakage of e- as they move to form QH2
44
how are electrons transferred in succinate ubiquinone oxidoreductase?
1) succinate is oxidized to fumarate and the e- are passed to FAD which is then reduced to FADH2 2) the e- in FADH2 are passed to the Fe-S one at a time and is picked up by Q which is reuduced to QH2
45
what enzyme in the NADH shuttle system oxidizes NADH coming from glycolysis?
cytosolic 3-phosphoglycerol dehydrogenase
46
what enzyme in the NADH shuttle system reduces FADH, odizing 3-phosphoglycerol into DHAP?
mitochondrial 3-phosphoglycerol dehydrogenase
47
what is Q a substrate for in the NADH shuttle system into the mitochondria?
substrate for the mitochondrial 3-phosphoglycerol dehydrogenase
48
where does the NADH shuttle system occur? what are the pros and cons of this shuttle system?
brain and muscle pro: quick con: doesn't yield as much energy as the malate-aspartate shuttle system
49
why is less energy produced when using the NADH shuttle system?
it bypasses complex 1 so less H+ are pumped
50
what 2 important molecules do not have transporters across the IMM?
OAA and NADH
51
where does the malate-aspartate shuttle occur?
kidney, liver and heart
52
what are the pros and cons of the malate-apartate shuttle?
pros: yields more energy because NADH enters at complex 1 cons: takes longer due to many step conversions
53
explain how NADH is produced with the malate-aspartate shuttle?
1) OAA is reduced to malate in the cytosol with cytosolic malate dehydrogenase 2) malate is able to cross the membrane and enter the matrix through transporters 3) malate is oxidized by NAD+ using matrix malate dehydrogenase to yield OAA and NADH 4) NADH is taken to ETC and OAA then goes through a transamination and is converted to aspartate to be able to cross back over the membrane and continue the shuttle cycle 5) once in the matrix, aspartate is deaminated and converted back to OAA
54
what determines which way the aspartate-malate shuttle system will direct the conversions?
the cytosolic conditions
55
what kind of gradient is responsible for movement of electrons in the ETC?
H+ electrochemical gradient
56
how is the electrical, chemical and pH gradient created in the ETC?
electrical- e- transport across complexes chemical- difference of protons from matrix and mitochondrial pH- higher [H+] in the intermembrane space
57
is the pH higher in the matrix or intermembrane space?
in the matrix (less H+)
58
what regulates the rate of oxidative phosphorylation and aerobic catabolism?
coupling
59
is the matrix or intermembrane space more positive?
the IMS is more positive due to the movement of H+ out of the matrix
60
what components are present in the ATP synthase? what are they responsible for? and how do they function?
F0: crosses the membrane as alpha helices and is the proton channel -rotates as protons move through, transferring kinetic energy to F1 F1:Catalytic component that extends into matrix. ATP synthesis occurs here. composed of alternating α,β units and a γ subunit -γ unit rotates in response to F0 movement, causing a conformation change in αβ. -ADP and Pi are bound and converted into ATP
61
how many e- must pass through the ATPase to yield 1 water molecule?
2 e- = 1 water
62
should you include water movement in ATPase in questions that ask about water needs of metabolism?
no
63
how many H+ are transported through F0 to for 1 ATP?
3H+
64
What does the 0 in F0 subunit mean?
it is sensitive to oligomycin
65
how many H+ are pumped for 1 complete turn of the ATPase?
10H+
66
what does rotational catalysis refer to? explain this process
the binding mechanism for ATP synthesis In the L conformation ADP and Pi bind loosely and is catalytically inactive In the T conformation ADP and Pi are tightly bound and ATP is made (catalytically active) In the O (open) confirmation, there is a low affinity for ligands and ATP is released. (catalytically inactive)
67
what causes the change in confirmation in rotational catalysis?
The rotation of γ, causing changes in the conformation of the α,β dimers
68
What types of transporters are seen in the ETC? what do they transport?
Adenine nucleotide translocase (antiporter) -brings ADP into matrix and ships ATP out H+ phosphate symporter -brings Pi into the matrix with H+ to be used as a substrate for ATP synthesis
69
what part of the gradient does the adenine nucleotide translocase utilize?
electrical
70
Why are 4H+ needed to make ATP?
3 H+ for the ATPase + 1H+ needed to bring Pi into the matrix
71
what is the PO ratio?
the amount of ATP made per Oxygen consumed
72
what is the PO ratio for NADH? where is this different? why?
2.5 -this is not the case for NADH in the brain and muscle because the Phosphate glycerol shuttle system is used do to its faster ability to generate enegry -this shuttle system by passes complex 1, meaning less ATP is made
73
what is the H+ gradient generated from 2 e- coming in at complex 1? what about from comlex 2?
gradient of 10 from complex 1 gradient of 6 from complex 2
74
what is the PO ratio of FADH2?
1.5
75
True or False: the electron transport is what drives the synthesis of ATP
False, the electrochemical gradient created from the H+ movement is what is responsible for the generation of ATP -as long as there is a H+ gradient, ATP can be synthesized (racker experiment)
76
what is the effect of an uncoupler? what is an example of an uncoupling protein?
uncoupling allows H+ to bypass ATP synthase into the matrix without making ATP (produces heat) -thermeogenin
77
What are the metabolic results of uncoupling?
1) decreased ATP synthesis 2) increased O2 consumption 3) increased heat production
78
why does O2 consumption increase in the presence of an uncoupler?
in order to maintain the electrochemical gradient, the ETC speeds up, consuming more O2 as the H+ pumping increases
79
where is brown fat located? what is its purpose?
found in areas where no muscle contraction occurs (skull, spine, major arteries) -Uncoupling occurs here for heat generation in animals that do not shiver
80
what is the effect of norepinephrine on brown fat? why is this?
Nep will increase heat generation through uncoupling - it is very sensitive to signals from the nervous system
81
what is the mechanism for uncoupling of mitochondria in brown fat? what effect does fat have on uncoupling protein?
It is a G-coupled mechanism and is stimulated by norepinephrine the phosphorylation of Hormone-sensitive triacylglycerol is units active form and will break down TAGs to release free fatty acids -free FA bind directly to uncoupler proteins to open it -free FA have electrons that supply energy to the ETC
82
what signals inhibit uncoupler protein (thermogenin) in non-shivering thermogenesis?
ADP and GDP
83
what is the effect of DNP on oxidative phosphorylation?
It uncouples oxidative phosphorylation without disrupting mitochondrial structure the structure allows it to diffuse back and forth between the membrane and dissipate the gradient by displacing the [H+]
84
what do you expect to be added to a suspension of mitochondria at each point?
1: ADP + Pi 2: ATP synthase inhibitor 3: uncoupler
85
# **10 mark Q on final How does the ATP generation differ in skeletal muscle vs the liver given the complete oxidation of glucose? why?
30 in skeletal muscle and 32 in the liver the skeletal and brain use the phosphate glycerol shuttle system which yields less energy due to it bypassing complex 1 in the ETC
86
# **10 mark Q on final explain the ATP yield from the complete oxidation of glucose in muscle vs liver tissues:
From 1Glucose / 2 pyruvate LIVER Glycolysis: (7 ATP) -2 NADH (x2.5 = 5 ATP) -2ATP Pyruvate dehydrogenase: (5 ATP) -2 NADH (x2.5 =5 ATP) CAC : (20 ATP) -6NADH (x2.5 = 15 ATP) -2FADH (x1.5 = 3 ATP) -2GTP MUSCLE From 1Glucose / 2 pyruvate Glycolysis: (5 ATP) -2 NADH (x1.5 = 3ATP)* -2ATP Pyruvate dehydrogenase: (5 ATP) -2 NADH (x2.5 =5 ATP) CAC : (20 ATP) -6NADH (x2.5 = 15 ATP) -2FADH (x1.5 = 3 ATP) -2GTP
87
88
why is glucose oxidation ~30% efficient?
breakdown of glucose to CO2 yields ~2800kj of energy formation of 32 ATP uses ~800 kj of energy 800 / 2800 ~30% ** closer to 34% with actual numbers
89
what is oxidative phosphorylation majorly regulated by?
cellular needs -ADP (most important) and Pi supply -NADH / NAD+ ratio -O2 supply (rarely an issue)
90
what is the MOST important factor affecting oxidative metabolism?
Energy state of the cell (ATP/ADP in the matrix) Redox state of the cell (NADH:NAD+) *the activity of the ETC controls the activity of oxidatuev metabolism and not the other way around
91
what is oligomycin an inhibitor of?
The F0 component of the ATP synthase
92
what is thermogenin also reffered to? what does it do?
Uncoupling protien 1 (UCP1) -natural uncoupler that facilitates protons across the inner mitochondrial membrane without the use of the ATP synthase (dissapating the H+ gradient) -found in brown adipose tissue and regulated by FA and bodily needs
93
what is the role of DNP? where does it act?
chemical uncoupler of oxidative phosphorylation -less regulated than thermogenin making it more dangerous
94
How much water is produced from the complete aerobic oxidation of 1 glucose molecule? explain where the water comes from
10 H2O molecules Glycolysis: 2 NADH 2ATP 2H2O Pyruvate dehydrogenase: 2NADH CAC: 6NADH 2FADH2 2GTP 4 H2O consumed 10 NADH = 10 H2O 2 FADH2 = 2 H2O + 2H2O =14 H2O produced - 4H2O from CAC =10 H2O

BIOCH 310 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions