Terminal Respiration Flashcards

1
Q

Where is most NADH and FADH2 produced?

A

In the mitochondrial matrix from CAC and beta-oxidation.

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2
Q

Where else is NADH produced?

A

In the cytosol from glycolysis.

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3
Q

How is NADH transferred to the mitochondrial matrix?

A

By the glycerol phosphate shuttle:

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4
Q

How does the glycerol phosphate shuttle work?

A

electrons from NADH transferred to make G-3-P which crosses outer membrane and transfers electrons to form FADH2.

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5
Q

Why is there an energetic cost to using cytosolic reduced substrates in terminal respiraiton?

A

FADH2 doesnt pass electons throught he 1st complex so produces less ATP than NADH. Therefore theres a cost to using cytosolic NADH as it becomes FADH2.

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6
Q

Why is ubiquinone used as a dietary supplement?

A

It reduces free radicals so is used as an antioxidant.

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7
Q

Complex 1:

A
  • Oxidises NADH
  • e-‘s passed along Fe-S centres
  • Produces ubiquinol (QH2) from matrix H+ ions and e-‘s
  • 4H+ ions pumped out the matrix
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8
Q

Complex 2:

A
  • Oxidises FADH2
  • Fe-S centres channel e-‘s
  • Transfers e-‘s to form ubiquinol
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9
Q

Complex 3:

A
  • Ubiquinol from 1&2 gives up electrons to reduce cytochrome c
  • Each QH2 reduces 2 cytochrome c molecules
  • Pumps 2 protons out the matrix.
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10
Q

Complex 4:

A
  • e-‘s from cytochrome c channled through Fe-Cu centres
  • e-‘s pass to O2 which makes water with matrix protons
  • 4 more protons pumped through
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11
Q

How many protons are pumped across for every NADH oxidised?

A

10 H+ ions or protons

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12
Q

How many protons are pumped across for every FADH2 oxidised?

A

6 H+ ions of protons

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13
Q

What is Chemiosmosis?

A

Movement of protons down the electrochemical gradient to produce a proton motive force.

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14
Q

Why is chemiosmosis vectoral?

A

It has a specific directionality of movement

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15
Q

What generates the electrochemical gradient?

A

The chemical potential (alkaline inside, acidic outside)

The elecrical potential (-ve inside and +ve outside)

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16
Q

What is ATP synthase?

A

A large multi-subunit protein complex in inner mitochondrial membrane.
Split into F0 and F1

17
Q

What is the F0?

A

Membrane bound proton conduction unit.

10 subunits in the channel and 1 connecting to F1 (gamma shaft).

18
Q

Whats the F0 function?

A

It captures energy from the proton motive force.

19
Q

What is the F1?

A

Protudes into matrix. Made from alpha & beta subunits.

20
Q

Function of F1?

A

It uses energy captured by F0 to synthesize ATP

21
Q

What are the 3 beta subunit types?

A
  • one binds to ATP
  • one binds to ADP + Pi
  • One cant bind to either
22
Q

How is ATP synthesised?

A
  • F0 captures energy from proton motive force
  • > F0 rotates
  • > Gamma shaft rotates
  • > Forces conformational changes in beta subunits
23
Q

How many protons need to pass through ATP synthase for 1 ATP to be made?

A

3 protons pass through before 1 conformational change occurs.

24
Q

How much ATP does NADH and FADH2 produce?

A

Every mole of NADH oxidised forms 2.5 moles of ATP.

One mole of FADH2 oxdisied forms 1.5 moles of ATP.

25
Q

What is coupling?

A

Electron transport is said coupled to atp SYNTHEsis.

26
Q

How does uncoupling occur?

A

The inner membrane becomes permeable to protons.
Proton gradient cant be generated.
No ATP can be made.

27
Q

What happens to energy generated by electron transport when uncoupled?

A

Its released as heat

28
Q

What is malignant hyperthermia?

A

A disease caused by leaky membranes when susceptible people are exposed to halothane.

29
Q

What does a large body temp increase cause?

A

Irreversible muscle dAMAGE

30
Q

When does intnetional uncoupling occur in mammals?

A

When infants are too cold
norepinephrine opens a thermogenin channel in the inner membrane making it leaky to protons
Heat is released to warm up the infant.
(brown fat)

31
Q

When does intentional uncoupling occur in plants?

A

Arum lily do it to attract insects to its heat

Skunk cabbage does it to melt snow