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Lecture 28 Flashcards

1
Q

what is Phosphate Transfer Potential?

A

Free energies of hydrolysis for phosphate-containing compounds

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2
Q

What is the order from highest to lowest free energy change of phosphate transfer potentials?

A
  • Glycolysis intermediates
  • Phosphocreatine
  • thioester
  • ATP
  • Glucose 6-phosphate (glucose intermediate
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3
Q

Why can one phosphate transfer be used to create a phosphate bond?

A

Because it takes less energy to make the phosphate bond in one process than the energy released when a phosphate bond is broken in another process

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4
Q

If a reaction is coupled, what must the free energy chnage of the combined reactions add up to?

A

A negative number

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5
Q

When coupling two reactions with separate free energy changes what must be done?

A

One reaction will have a negative free energy change and the other will have a positive one (if not flip the reactions and the sign of the reaction). Then cancel out what is the same in both reactions and add the free energy changes

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6
Q

What are the reactants and products of the hydrolysis of phosphocreatine?

A

Reactants: Phosphocreatine, H2O
Products: Creatine, Pi

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7
Q

What is the free energy change of the hydrolysis of phosphocreatine?

A

-43kj/mol

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8
Q

What can phosphocreatine be used to make?

A

ATP

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9
Q

Why can phosphocreatine be used to create ATP?

A

Because the energy of hydrolysis is greater than the energy required to phosphorylate ADP

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10
Q

What does the product of the dephosphorylation of phosphocreatine resemble?

A

Arginine

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11
Q

What is phosphocreatine used for?

A

A transient source of ATP

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12
Q

What is the free energy required for the synthesis of ATP?

A

32kJ/mol

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13
Q

What is AcetylCoA produced from?

A

Fat, protein, and carbohydrate metabolism

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14
Q

What is AcetylCoA a central molecule in?

A

Aerobic catabolic processes

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15
Q

What cycle does AcetylCoA go into?

A

The citric acid cycle

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16
Q

What does the Citric acid cycle produce?

A

Lots of reduced cofactors (NADH/FADH2)

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17
Q

What are reduced cofactors?

A

High energy structures that are reduced

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18
Q

What reduced cofactors can the citric acid cycle produce?

A

NADH and FADH2

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19
Q

What occurs in oxidative phosphorylation?

A

The reduced cofactors are converted into ATP and oxidized back to their oxidized forms

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20
Q

What are the two puposes of Catabolic pathways?

A
  • Breakdown of larger molecules into smaller building units

* Release and (temporary) storage of energy in high-energy molecules

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21
Q

What are some high energy molecules used to store energy after catabolism?

A
  • ATP/NTP

* Reduced cofactors (NADH/FADH2)

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22
Q

What can the reduced cofactors produced in catabolism be used for?

A

Oxidative phosphorylation to generate ATP

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23
Q

What are the two processes that occur in oxidative phosphorylation?

A
  • Oxidation of reduced cofactors (NADH, FADH2)

* Phosphorylation of ADP to ATP

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24
Q

What is the reaction of the oxidation of NADH?

A

NADH ➡️ NAD+ + H+ + 2e

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25
What is the reaction for the oxidation of FADH2?
FADH2 ➡️ FAD + 2H+ + 2e
26
What does the oxidation of the NADH and FADH2 go on to do?
Reduce O2 to H2O
27
For how many what does the reduction of O2 molecules in oxidative phosphorylation produce?
Two water molecules
28
What is the reaction for the reduction of O2 in oxidative phosphorylation?
4H+ + 4e + O2 ➡️ 2H2O
29
How is the oxidation of reduced cofactors and the phosphorylation of ADP to ATP in oxidative phosphorylation connected?
Through a proton gradient across the mitochondrial membrane that is created by one process and used by another
30
What generates the proton gradient in oxidative phosphorylation?
Electron transport in the oxidation of NADH and FADH2
31
What consumes the energy gradient produced in oxidative phosphorylation?
ADP to create ATP and synthesize phosphoanhydride bonds
32
What are reduced cofactors (NADH, FADH2) generated from?
Glycolysis and the citric acid cycle (oxidative processes)
33
Where do the reduced cofactors in oxidative phosphorylation feed their electrons?
To the electron transport chain
34
What occurs once reduce cofactors feed their electrons to the electron transport chain?
They become oxidized and O2 becomes reduced to water
35
What occurs in oxidative phosphorylation once NADH and FADH2 are oxidized and O2 is reduced to H2O?
A proton gradient is produced and used for ATP synthesis
36
Where does oxidative phosphorylation occur?
Across the inner mitochondrial membrane
37
How many membranes do mitochondria have?
Two membranes
38
What are the characteristics of the outer mitochondrial membrane?
* Very porous | * Has porins
39
What are the characteristics of the inner mitochondrial membrane?
Doesn't let things pass through easily
40
What are the components to the electron transport chain?
* Complex I * Complex II * Complex III * Complex IV * Coenzyme Q * Cytochrome C
41
What kind of enzyme is Coenzyme Q?
A lipid soluble coenzyme
42
What kind of protein in Cytochrome C?
A peripheral membrane protein
43
What are type of protein are complexes I - IV?
They are integral, transmembrane membrane proteins
44
What are complexes I - IV in the electron transport chain involved in?
Proton translocation
45
What does Coenzyme Q do?
Takes electrons from proteins I and II and takes them to protein III
46
Which surface does Cytochrome C sit on?
The outer surface of the inner mitochondrial membrane (the intermembrane space)
47
What happens to cofactors during electron transport in oxidative phosphorylation?
They are reversibly oxidized and reduced
48
What are the cofactors involved in oxidative phosphorylation?
* Flavin mononucleotide * Iron-sulfur clusters * Copper (cu2+) * Cytochrome heme groups * Coenzyme Q
49
What is the lipid soluble cofactor in oxidative phosphorylation?
Coenzyme Q
50
What are the prosthetic group cofactors in oxidative phosphorylation?
* Flavin mononucleotide * Iron-sulfur clusters * Copper (Cu2+) * Cytochrome heme groups
51
What is the basis of reduction potentials of cofactors that electrons move through in oxidative phosphorylation?
Electrons move from cofactors with lower reduction potential to those with higher reduction potentials
52
What is the electron transport chain?
A series of connected redox reactions that move electrons from one location to another
53
Where are the cofactors that are prosthetic groups located?
They are prosthetic groups within the integral membrane proteins or cytochrome C
54
What do prosthetic groups and cosubstrates have in common?
They are both cofactors
55
What are cosubstrates?
A subset of cofactors
56
What is the difference between prosthetic groups and cosubstrates?
Whether or not they are incorporated into the protein structures
57
What is the difference between Flavin mononucleotide (FMN) and FAD/FADH2?
FMN has no Adenosine so it is just a mononucleotide
58
What is the reaction for the reduction of FMN?
FMN +2H+ + 2e ➡️ FMNH2
59
What is the reduced form of FMN?
FMNH2
60
What are Iron-Sulfur clusters?
The product when iron and sulfur come together
61
What is the reaction for Iron-Sulfur Clusters?
Fe3+ + e- ➡️ Fe2+
62
What are Cytochromes?
Hemoproteins that carry out electron transport
63
What is the difference in heme in hemoglobin and myoglobin vs cytochromes?
In Cytochromes the heme groups switch between oxidized and reduced states
64
What is the solubility of Coenzyme Q (Q)?
It is lipi soluable
65
What does Coenzyme Q do?
Transports electrons to complex III from Complexes I and II in the inner mitochondrial membrane
66
What is Coenzyme Q a cosubstrate for?
Complex I, II and III
67
What is the formula for the reduction of Q?
Q + 2H+ + 2e ➡️ QH2
68
What makes Coenzyme Q hydrophobic?
Its hydrocarbon structure
69
What does Q being hydrophobic allow it to do?
Dissolve within the hydrophobic core of the inner mitochondrial membrane and interact with transmembrane portions of integral membrane proteins
70
What redox reactions have a free energy change related to?
Reduction potential
71
What is reduction potential?
Affinity for electrons
72
What does a higher reduction potential change mean?
More negative 𝛥G
73
Where do electrons move in regards to reduction potential?
Electrons move from compounds with lower reduction potentials to those with higher reduction potentials
74
What is a positive change in reduction potential associated with?
A negative change in free energy
75
What can the free energy from redox reactions be used to transport?
Protons across the membrane (1º active transport)
76
Which complex is not involved in the oxidation of NADH?
Complex II
77
What is the first step in the electron transport chain for NADH?
It is oxidized at complex I to for NAD+
78
What happens once NADH is oxidized to form NAD+ in the electron transport chain?
Two electrons pass into complex one (reducing it) and then passing the electrons to coenzyme Q
79
What happens once coenzyme Q takes the electrons from NADH from Complex I?
It becomes reduced to QH2 and diffuses through the membrane to complex III
80
What happens once Complex III takes the electrons from Coenzyme Q?
Coenzyme III becomes reduced and passes electrons to Cytochrome C which passes electrons to complex IV which passes the two electrons to O2 to form H2O
81
Why is oxygen the terminal electron acceptor?
Because it has a very high reduction potential
82
What happens in the electron transport chain when NADH is oxidized?
2e go to complex I. Complex I gives them to Q. Q gives them to complex III. III give them to Cyt C. Cyt C gives them to IV. IV gives them to O2
83
How many protons can be move out of the matrix once NADH is Oxidized?
10 Protons
84
How many protons are moved at each complex with NADH?
I: 4H+ III: 4H+ IV: 2H+
85
What cofactors does complex I have?
FMN and Fe-S
86
What cofactors does complex III have?
Fe-S and Cyt b (heme groups)
87
What cofactors does complex IV have?
Heme groups
88
What are the cofactors in Complex II?
FAD as a prosthetic group and Fe-S

Biocheem (38 decks)

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