Oxidative Phosphorylation 1 Flashcards by Zunaira Ali

What is oxidative phosphorylation

the electrons in NADH and FADH2 from TCA

transported down the electron transport chain via oxidation reduction reactions

How well did you know this?

Not at all

Perfectly

Where does the ETC happen

In the mitochondrial memebrane

How well did you know this?

Not at all

Perfectly

How many protien complexes are in the ETC

4 (I-IV)

How well did you know this?

Not at all

Perfectly

What are the elections carriers/“taxis” in the etc

Ubiquinone (Q)

Cyctochrome C

How well did you know this?

Not at all

Perfectly

Where do electrons come from in the etc

NADH or FADH2

How well did you know this?

Not at all

Perfectly

What is the final electron acceptor in the ETC

oxygen which turns into H2O

How well did you know this?

Not at all

Perfectly

As electrons flow from NADH and FADH2 to Oxyegn in the ETC, what is the delta G

-220

Highly exergonic

How well did you know this?

Not at all

Perfectly

What is the symbol for redox potential

E^’•

How well did you know this?

Not at all

Perfectly

What is used as a reference in measuring redox potential

Which way do electrons flow

Hydrogen

From the sample to the standard half cell

How well did you know this?

Not at all

Perfectly

What does it mean when you have a negative reduction potential

The oxidized substance has a lower affinity for electrons than the H2 reference

The easier it is for the element to be oxidized

How well did you know this?

Not at all

Perfectly

If the reaction is flipped so that the sample is getting reduced and the standard is getting oxidized what happens

Ie, electrons are flowing in the opposite direction

The reduction potential flips and becomes positive

How well did you know this?

Not at all

Perfectly

What does postivtice reduction potential mean

It means that the oxidized substance that lost electrons has a higher affinity for elections than the standard hydrogen electrode

(Would rather be reduced)

How well did you know this?

Not at all

Perfectly

Does oxygen have a positive or negative reduction potential

What does this mean

Has a postive reduction potential,

It’s better at being reduced and taking in electrons

How well did you know this?

Not at all

Perfectly

Does NAD+ have a negative or positive reduction potential?

What does this mean

Negative

This means that it is better at being oxidized and giving up electrons

Would rather stay in the from it’s in

How well did you know this?

Not at all

Perfectly

How to calc delta g

Slide 11

How well did you know this?

Not at all

Perfectly

What happens in the first part of the electrons transport chain

Nadh in the matrix transfers electrons to complex 1

While it does this, FADH2 transfers electrons to complex 11

Why does FADH first transfer electrons to complex 11 instead of complex one like Nadh

It has a less negative reduction potential than Nadh

Meaning it’s not as good at being oxidized as NAHD

What oxidizing agent is present in all four complexes in the ETC and in cytochrome c

Why

Iron as a prosthetic group

It has a positive reduction potential so it’s good at being reduced and oxidizing NADH and FADH2

What does the reduction potential of iron depend on?

What does iron appear as in the etc

Is depends on the environment surrounding it

As Iron Sulfur Clusters

In addition to iron, what else is in
Complex 4 of the etc?

What is another name for complex 4

Copper (gets reduced)

cytochrome c oxidase

What is coenzyme Q in the ETC

It is ubiquinone and it moves electrons from complex one and 2 to complex 3

What is the properties of coenzyme Q

It’s a ubiquitous quinone

It has isoprene units which are just hydrophobic tails

It shuttles both electrons and protons through the ETC

Which complexes in the ETC pump protons

How does it do this

1 3 and 4

Because the reaction is exergonic

Why are protons not pumped out complex 2

Since fadh2 doesn’t interact with complex one, less protons are pumped out

What is the proposed model of how protons are pumped out of complex one in the ETC

Q (ubiquinone) binds to complex one in a deep channel Through the iron sulfur clusters, electrons flow from NADH to ubiquinone The membrane arm moves protons from lys/glu residues to Q2- to make QH2 A change in the structure happens where QH2 leaves and protons get taken up and a total of 4 protons is released by NuoL in the membrane

What makes the 4 protons in NuoL get ejected in complex 1

Electrostatic pressure

How does complex 11 in TCA work What is it called

The succinate Q reductase complex Succinate dehydrogenase from TCA is part of this complex FADH2 is a prosthetic group of this complex which gets oxidized and reduced ubiquinone to make QH2 (ubiquinol)

What are the electron carriers in complex 11 of the ETC

Fad+, iron sulphur protiens, coenzyme Q

How does complex three of TCA work and what is it named

Cytochrome c reductase/Q-cytochrome c oxidoreductase The pervious ubiquinol (QH2) move from complex 1 and 11 to complex 111 At complex 111, it gives up 2 electron but cytochrome C (electron taxi) take 1

How many electrons have cytochrome C accept

1 electron

What subunits are invoked in the complex 111 structure

Cytochrome c which has a heme subunit Cytochrome BL and Bh Iron sulfur groups

How is the problem of cytochrome c only taking one electron fixed

The Q cycle

What is the Q cycle first half

When QH2 bind to complex 111, two protons a released to the IMS (inter membrane space) Cyt C gets one electron and move to complex 4 the other electron moves from cyt B to Q to make a Q•- radicle Then this oxidized Q radical moves off of complex 111

What is the Q cycle second half

A second QH2 bind to complex 111 Two protons from it are moved to IMS One e moves to cyt c again and is move to complex four again The other is moved through cyt B to the Q radical and two hydrogen from the IMM turn it into QH2

What happens in complex 4 what is it called

Cytochrome c oxidase After cyt c gets an electron, it moves to complex 4 to get reduced and give up its electrons 2 moclecules of cyt c bind and transfer two electrons to the fe and Cu prosthetic groups of the complex The reduced prosthetic group bind to o2 and make a PEROXIDE BRIDGE Two more cyt c bind again and 2e and 2H from the matrix cleave the bridge and make OH on either side 2 H from the IMM go to this broken bridge and release 2 H2O from it 2H2O goes to the imm

In complex four where do all of the hydrogen in the reaction come from

Not the IMS, from the IMM

Per one reaction in complex 4 (4 cyt c reductions) how much protons are use up How much is sent to the IMS

4 protons from the IMM are used up But 4 are also sent to the IMS

In complex three how many protons are move to the IMS

What are the ETC oragsinzed into and how does this help

Into a respirasome This improved the efficiency and moves the substrate and electrons from one complex to the next