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Year 1 NME > The Mitochondrial Respiratory Chain and Oxidative Phosphorylation > Flashcards

The Mitochondrial Respiratory Chain and Oxidative Phosphorylation Flashcards

1
Q

What are the 2 membranes of the mitochondria called?

A

1 - inner membrane

2 - outer membrane

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2
Q

What is the area between the inner and outer membrane of the mitochondria called?

A
  • intermembrane space
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3
Q

The inner membrane of the mitochondria folds to increase surface area, what are these folds called?

A
  • crista
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4
Q

What is the area within the inner membrane called?

A
  • matrix
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5
Q

Where is the electron transport chain located in the mitochondria?

A
  • on the inner membrane
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6
Q

Where is the ATP synthase located in the mitochondria?

A
  • on the inner membrane
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7
Q

What are the outer and inner membranes of the mitochondria permeable to?

A
  • outer = freely permeable to small molecules and ions
  • inner = impermeable to small molecules and ions, including H+
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8
Q

Where does the citric acid cycle take place in the mitochondria?

A
  • within the matirx
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9
Q

NADH + H+ from the citric acid cycle enter the electron transport chain where?

A
  • complex 1
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10
Q

FADH2 from the citric acid cycle enter the electron transport chain where?

A
  • complex 2
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11
Q

When nicotinamide adenine dinucleotide (NAD+) is in this form it is said to be in its oxidised form. What does this mean?

A
  • oxidation means loss of electrons so it has a + charge
  • so NAD+ is positive and can accept electrons
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12
Q

When nicotinamide adenine dinucleotide (NAD+) is in this form it is said to be in its oxidised form, meaning it is positive and can accept electrons. If the NAD+ gains an electron, what else does it gain and then become?

A
  • when it gains an electron it becomes negatively charged
  • then attracts positively charged H+
  • NAD+ then becomes NADH
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13
Q

When nicotinamide adenine dinucleotide (NAD+) is in this form it is said to be in its oxidised form, meaning it is positive and can accept electrons. If the NAD+ gains an electron it becomes negatively charged and then attracts a positively charged H+. The NAD+ then becomes NADH and is in its reduced form. What does the reduced form actually mean?

A
  • when a molecule gains an electron
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14
Q

In glycolysis glucose is able to donate an electon to NAD+, which can then become what?

A
  • NADH = reduced form gaining electron and H+
  • this is the electron transport shuttles used in metabolism
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15
Q

NADH is described as an electron transport shuttle. NAD+ is reduced (gaining an electron and H+) into NADH throughout glycolysis and the citric acid cycle. Where do the NADH then take all of these electrons?

A
  • electron transport chain in the mitochondria
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16
Q

Flavin adenine dinucleotide (FAD) is the oxidised form of this molecule and is an important co-enzyme. Where does FAD become FADH2?

A
  • in citric acid cycle
  • 1 hydrogen and 2 electrons are added to FAD during the conversion of succinate to fumarate
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17
Q

Flavin adenine dinucleotide (FAD) is the oxidised form of this molecule and is an important co-enzyme. FAD is reduced and becomes FADH2 with the addition of one hydrogen and 2 electrons in citric acid cycle during the conversion of succinate to fumarate. Why is FADH2 important in metabiolism?

A
  • FADH2 can carry electrons to the electron transport chain
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18
Q

In complex 1 NADH releases 2 electrons which work there way through the complex and eventually bind with what?

A
  • ubiquinone, more commonly known as coenzyme Q
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19
Q

In complex 1 NADH releases 2 electrons which work there way through the complex and eventually bind ubiquinone, more commonly known as coenzyme Q. In addition the electrons release energy throughout complex 1 and cause what to happen?

A
  • complex 1 pumps 4 H+ into intermembrane space
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20
Q

In complex 1 NADH releases 2 electrons which work there way through the complex and eventually bind ubiquinone, more commonly known as coenzyme Q. In addition the electrons release energy throughout complex 1 and complex 1 then pumps 4 H+ into the intermembrane space. What is the overall reaction that occurs here?

A
  • NADH, H+ and ubiquinone (Q) are converted into NAD+ and QH2
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21
Q

Following the binding of 2 electrons with ubiquinone (coenzyme Q) The reducef form of Q is formed making QH2. Where does QH2 then travel to?

A
  • diffuses into the lipid bilayer
  • binds with complex 3
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22
Q

Complex 2 is not involved in the pumping of H+ into the intermembrane space. However, it does have an important role, where FADH2 transfers its electrons into complex 2. What then happens to these electrons?

A
  • 2 electrons are transferred to ubiquinone (Q enzyme)
  • ubiquinone is reduced forming QH2
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23
Q

In complex 2 there is a heme molecule, what is the function of this heme molecule?

A
  • ensure electrons are transferred to ubiquinone
  • if they didnt the electrons may form reactive O2 species and damage the electron transport chain
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24
Q

Glycolysis is also able to donate electrons to the electron transport chain (ETC). How does this occur?

A
  • glyceraldehyde-3-phosphate (G-3-P) conversion to 1,3-bisphosphoglycerate (1,3 BPG) produces 1 NADH
  • this NADH can then be used in the ETC
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25
Q

Once ubiquinol (QH2) binds to complex 3, what happens to the electrons?

A
  • 1 electron at a time is able to bind with cytocrhome C
  • transfer of electrons through complex 3 release energy
  • released energy causes 4 H+ protons to be pumped into intermembrane space
26
Q

Cytochrome C is a soluble protein of the intermembrane space. It can only bind with one electron at a time, but it transports electrons across the electron transport chain via the intermemrane space. Thiis is facilitate by a heme group, which binds an electron and becomes Fe3+, then once is transfers the eelctron it then becomes Fe2+. Where does cytochrome C transfer electrons from and to?

A
  • between complexes 3 and 4
27
Q

Once cytochrome C binds with complex 4, what happens?

A
  • movement of electrons through complex 4 produces energy
  • energy produced means complex 4 can pump 2 H+ into intermembrane space
28
Q

Once cytochrome C binds with complex 4, the energy released from the electrons caused complex 4 to pump 2 H+ into the intermembrane space. However, what happens to the electrons as there is now nowhere for them to be transferred?

A
  • electrons bind to iron-copper centre
  • heme a3 then binds to O2
  • O2 then binds with H+ forming H2O
29
Q

In the elctron transport chain, for every NADH, how many H+ are pumped into the intermembrane space?

A
  • 10
  • complex 1 = 4 H+
  • complex 3 = 4 H+
  • complex 4 = 2 H+
30
Q

What is the Chemiosmotic model of ATP synthesis?

A
  • a theory suggests that most ATP synthesis in respiring cells comes from the electrochemical gradient across the inner membranes of mitochondria
31
Q

The Chemiosmotic model of ATP synthesis suggests that most ATP synthesis in respiring cells comes from the electrochemical gradient across the inner membranes of mitochondria. What generates the electrochemical gradient?

A
  • high concentration of H+ in intermembrane space creates highly + charge compared to - charge in matrix
  • also creates high chemical concentration of H+ in intermembrane space
  • this is called the proton motive force
32
Q

In addition to the chemical (high H+ concentration) and electrical charge (H+ positive charge), what else is different between the matrix and intermembrane space, that is driven by H+?

A
  • intermembrane will have a lower pH
33
Q

What 3 things in the mitochondria contribute towards the proton motive force?

A

1 - high H+ chemical concentration in intermembrane space

2 - high + charge driven by H+ in intermembrane space

3 - low pH driven by H+ in intermembrane space

34
Q

H+ is only able to enter the matrix again through one avenue, what is this avenue?

A
  • ATP synthase
35
Q

ATP synthase is responsible for ATP synthesis. There are 2 main parts of ATP synthase, F0 and F1. Where do F0 and F1 sit in the mitochondria?

A
  • F1 = inside matrix
  • F0 = inside inner membrane
36
Q

The F0 part of ATP synthase is made up of the C12 subunit which is a cylinder. Why is this important?

A
  • the C12 cylinder rotates
37
Q

What part of the ATP synthase connects the F1 and F0 parts of ATP synthase?

A
  • a subunit called gamma
  • it starts in F0 and runs through the middle of the F1 domain
  • surrounded in F1 domain by alpha and beta subunits
38
Q

In the F1 domain what holds the alpha and beta subunits in place that is also connected to the F0 domain and the inner membrane?

A
  • the delta subunit
39
Q

The F1 region of the ATP synthase is made up of alpha and beta subunits, with a gamma subunit that runs throught the middle. This forms alpha-beta pairs, but is it the alpha or beta subunits that actually form ATP?

A
  • 3 beta subunits have catalytic sites
  • ATP synthesis occurs at the catalytic sites
40
Q

If one alpha-beta pair changes shape, what happens to the other alpha-beta pairs?

A
  • they all have conformational changes
41
Q

What causes the C12 cylinder in the F0 part of ATP synthase to rotate?

A
  • H+ protons
42
Q

What is the binding-change model for ATP Synthesis?

A
  • mechanism of how ATP synthase forms ATP from ADP+Pi
  • B subuntis take turns to synthesis ATP
  • B subunits start in a conformation for binding ADP and Pi this is called B-ADP conformation
43
Q

The binding change model of ATP synthesis is a mechanism of how ATP synthase synthesises ATP through the Beta subunits. What are the 3 different conformational shapes these Beta subunits can take to synthesis ATP?

A

1 - conformation of Beta subunit for ADP and Pi binding

2 - Beta subunit changes conformation so that ADP and Pi can be brough together to form ATP

3 - Beta subunit changes conformation to give the active site a very low affinity for ATP called b-empty’ conformation, so ATP is released

44
Q

The binding change model of ATP synthesis is a mechanism of how ATP synthase synthesises ATP through the Beta subunits. What are the 3 different conformational names given to the 3 different conformations Beta subunits can take to synthesis ATP?

A

1 - Beta ADP conformation

2 - Beta ATP conformation

3 - Beta empty conformation

45
Q

If the Beta subunit in the middle has a Beta ATP conformation, what will the conformations either side be?

A
  • Beta empty conformation
  • Beta ADP conformation
46
Q

How many protons (H+) does it take to make the gamma subunit to rotate?

A
  • 3
47
Q

When the the gamma subunit turns and points at a Beta subunit, what does it cause that Beta subunit to become?

A
  • B empty conformation
  • the other 2 Beta subunits will become Beta ATP and Beta ADP
48
Q

For one full turn of the ATP synthase, how many protons are required?

A
  • 9
  • 3 for each Beta subunit change
49
Q

For one full turn of the ATP synthase we use 9 protons (H+), how many ATPs are synthesised?

A
  • 3
50
Q

How many protons (H+) are pumped into the mitochondrial intermembrane space by the electron transport chain if NADH and FADH release their electrons as they should?

A
  • 10 protons (H+)
51
Q

How many protons (H+) are pumped into the mitochondrial intermembrane space by the electron transport chain from 1 FADH2 if compelx 1 was not functioning?

A
  • 6 protons (H+)
  • this is if complex 1 is not functioning or no NADH is available
52
Q

How many protons (H+) are required to synthesis 1 ATP?

A
  • we need 3 in the ATP synthase
  • we also need 1 proton (H+) to get the phosphate into the matrix
  • 4 protons (H+) in total
53
Q

How is phosphate transported into the matrix to facilitate ATP synthesis?

A
  • via phosphate translocase
  • a symporter, H+ moves down concentration gradient and phosphate follows in the same direction
54
Q

How is ATP transported out of the matrix to be used as energy?

A
  • via adenine nucleotide translocase
  • a antiporter, ADP moves in and ATP moves out of the matrix
55
Q

How many ATP can we make from the complete oxidation of one glucose molecule?

A
  • 32
  • could be 30, but normally 32
56
Q

Normally electron flow, phosphorylation, the electron transport chain and ATP are tighly coupled. However, uncouplers, which essentially means taking apart are able to dissipate the pH gradient by doing what?

A
  • creating access for H+ to re-enter the matrix
  • less H+ in intermembrane space means less ATP synthesis
57
Q

Normally electron flow, phosphorylation, the electron transport chain and ATP are tighly coupled. However, uncouplers, which essentially means taking apart are able to dissipate the pH gradient by creating access for H+ to re-enter the matrix, meaning there is less H+ in intermembrane space and less ATP synthesis. This movement of H+ back into the matrix can. create energy that is lost through what?

A
  • heat
58
Q

Normally electron flow, phosphorylation, the electron transport chain and ATP are tighly coupled. However, uncouplers, which essentially means taking apart are able to dissipate the pH gradient by creating access for H+ to re-enter the matrix, meaning there is less H+ in intermembrane space and less ATP synthesis. This movement of H+ back into the matrix can. create energy that is lost through heat. What is a physiological example of this?

A
  • uncoupling protein 1 (UCP1) commonly called thermogenin
  • UCP1 is found in brown adipose tissue containing specific H+ channel where H+ will enter matrix creating heat
  • used by babies to generate heat by non-shivering thermogenesis
59
Q

In addition to physiological uncouples like in brown adipose tissue contributing to thermoregulation by heat generation, what other dangerous things can cause uncoupoling?

A
  • toxins and posions
  • cyanid for example
60
Q

In uncoupling reactions the electron transport chain recognised that there is a drop in ATP production due to H+ loss. It therefore does what to try and upregulate ATP synthesis?

A
  • raises the metabolic rate
  • increases electron transfer rate
  • increases temperature
61
Q

An agent: 2,4-dinitrophenol (DNP) is an exogenous agent that is a weak inner membrane acid. It is recognised as an exogenous uncoupoupling agent that is able to do what?

A
  • transport H+ across the inner membrane into the matrix
62
Q

An agent: 2,4-dinitrophenol (DNP) is an exogenous agent that is a weak inner membrane acid. It is recognised as an exogenous uncoupoupling agent that is able to transport H+ across the inner membrane into the matrix, which raises what, and what was this agent used for originally?

A
  • raises metabolic rate
  • used as a diet drug to lose weight
  • caused some deaths due to overdosing due to permanent uncoupling

Year 1 NME (61 decks)

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