Terminal Respiration Flashcards

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1
Q

Where is the only site of oxidative phosphorylation in eukaryotes?

A

The mitochondria

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2
Q

Where do NADH and FADH have to be for oxidation in the terminal respiratory system?

A

Mitochondrial matrix

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3
Q

How does the NADH and FADH that is formed in the cytosol reach the mitochondrial matrix?

A
  • The glycerol phosphate shuttle is used to move reducing equivalents across the membrane
  • Cytoplasmic NADH cannot cross the membrane but FADH can pass on its electrons on to the electron transport chain within the mitochondria.
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4
Q

How does the e’s of NADH get across the membrane of the mitochondria is it cannot cross the membrane?

A

Glycerol 3 Phosphate can cross the membrane and passes its e’s to FADH

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5
Q

What is the generation of ATP of FADH compared to NADH?

A

Less

An energetic price is paid for using cytosolic reduced co-substrates in terminal respiration

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6
Q

What is the name of complex I?

A

NADH-Q oxioreductase

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7
Q

What is the name of complex II?

A

Succinate-Q reductase

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8
Q

What is the name of complex III?

A

Q Cytochrome C oxioreductase

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9
Q

What is the name of complex IV?

A

Cytochrome C oxidase

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10
Q

What happens at complex I?

A
  • NADH is oxidised and e’s are passed to ubiquinone to give uniquinol (QH2)
  • H ions are pumped into the intramembrane space
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11
Q

What happens at complex II?

A

-FADH2 is oxidised and e’s are passed to ubiquinone to give ubiquinol

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12
Q

What is uniquinone?

A

Dietary supplement believed to reduce free radicals and thus acts as an anti-oxidant

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13
Q

What happens at complex III?

A
  • Passes the e’s form ubiquinol to cytochrome C
  • 1 ubiquinol is oxidise to yield 2 reduced cytochrome C molecules
  • Pumps protons into the intermembrane space
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14
Q

What happens at complex IV?

A

-Takes e’s from cytochrome c and passes them to molecular O2 to form H2O
-e’s channelled through Fe-Cu centre
Pumps protons into the intermembrane space

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15
Q

What does the conservation of energy from the breakdown of food molecules ultimately lead to?

A

The oxidation of NADH,FADH2, ubiquionone and cytochrome C

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16
Q

How is energy further conserved?

A

By the setting up of a proton gradient across the inner mitochondrial membrane

17
Q

How is the energy stored up in the H gradient used?

A
  • The EMF acts as a proton motive force and allows the proton gradient to work
  • A molecular turbine has ebeolved to harness the energy in the proton gradient-ATP synthase
18
Q

What is chemiosmosis?

A

As e’s pass trough the complexes of the transport chain protons move from the matrix to the outside of the inner mitochondrial membrane

19
Q

Why is the movement of protons across the mitochondrial inner membrane classed as vectoral?

A

It has a particular spatial directionality

20
Q

Why is the movement of protons across the mitochondrial inner membrane class as an energy transformation?

A
  • The protons on the outside of the membrane act as a store of potential energy
  • When these protons are allowed to flow back down their gradient they release energy to do work known as the proton motive force
21
Q

What happens at the sites where protons flow down their concentration gradient back to matrix of the mitochondria?

A

A large multi-unit protein complex called ATP synthase is found.

  • It has a mechanism which allows protons to flow through it.
  • As they flow through ATPase, the energy stored in the gradient is used to make ATP from ADP and Pi
22
Q

What are the 2 parts of ATPase?

A
  • F0

- F1

23
Q

What is F0 ?

A

It is a membrane bound protein conducting unit made of 10 subunits

24
Q

What does F1 do?

A
  • It protrudes into the mitochondrial matrix and acts as the catalyst for ATP synthesis.
  • It produces lots of ATP from the proton motive force energy collected by F0
25
Q

How is the reaction ADP>ATP catalysed/

A
  • ADP and Pi enter a B subunit

- The F0 cylinder and the y shaft forces conformation changes in the B subunits of F1 that catalyse the reaction

26
Q

What does the proton gradient force do in relation to ATP?

A

Drives its release

27
Q

What happens in the binding change mechanism?

A

-Protons moves from positive side of the membrane to the negative side#
-Sequenctial conformational changes of B subunit
B subunit that binds ADP+Pi
-B subunit that binds ATP
-B subunit that doesn’t bind ATP

28
Q

Electron transport and ATP synthesis are said to be coupled but how do they become uncoupled?

A
  • If the inner mitochondrial membrane becomes permeable to protons, the proton gradient cannot be generated-
  • If this happens the elctron transport can still occur with O2 being reduced to H2O but no ATP is made
29
Q

What happens to the energy created by the transfer of e’s along the terminal respiration system?

A

Released as heat

30
Q

What is malignant hyperthermia?

A

A disease caused by leaky mitochondrial membranes that uncouple electron transport and ATPsynthase

31
Q

When is intentional uncoupling seen in humans?

A
  • In the brown fat of newborns.
  • Brown fat contains lots of mitochondria
  • If a baby becomes cold, norepinephrine triggers the opening of a channel in a protein called thermogenin
32
Q

When is intentional uncoupling seen in plants?

A
  • Arum lily to attract insects

- Skunk cabbage to mel the snow that covers it