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1.1 POM Cells > Cell Integrity > Flashcards

Cell Integrity Flashcards

1
Q

How much energy does the average adult require?

A

8,400 kJ/day (83kg ATP)

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2
Q

What is the lifespan of an ATP molecule?

A

1-5 mins

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3
Q

How much ATP does a human contain?

A

250g

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4
Q

How many times is each ATP molecule recycled a day?

A

300

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5
Q

What does any interruption to oxidative phosphorylation lead to?

A

Cellular ATP depletion —> cell death

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6
Q

What are the 2 most common causes of OxPhos failure?

A

Hypoxia (less O2)
Anoxia (no O2)

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7
Q

How long does it take for cell death to occur after OxPhos failure in neurones vs muscle?

A
  • Neurones —> mins
  • Muscles —> hours
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8
Q

What is substrate level phosphorylation?

A

Production of ATP by the direct transfer of Pi from a substrate to ADP

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9
Q

What reaction occurs in the re-oxidation of NADH?

A

NADH + H+ + 1/2 O2 —> NAD+ + 1/2 H2O

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10
Q

What is the ΔG of NADH re-oxidation?

A

-220 kJ/mol

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11
Q

What reaction occurs in the re-oxidation of FADH2?

A

FADH2 + 1/2 O2 —> FAD + H2O

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12
Q

What is the ΔG of FADH2 re-oxidation?

A

-167 kJ/mol

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13
Q

What is the energy released from NADH/FADH2 re-oxidation used for?

A

Make phosphoanhydride bonds (between phophate groups in ATP)

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14
Q

What are the 5 parts of mitochondria?

A
  1. Outer membrane
  2. Inner membrane
  3. Intermembrane space
  4. Cristae
  5. Matrix
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15
Q

Where does OxPhos occur?

A

Inner mitochondrial membrane

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16
Q

What are cristae?

A

Folds of inner mitochondrial membrane to inc SA

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17
Q

What are the 4 membrane proteins in the ETC?

A
  1. Complex I = NADH dehydrogenase
  2. Complex II = Succinate dehydrogenase
  3. Complex III = Q-cytochrome C oxidoreductase
  4. Complex IV = Cytochrome C oxidase
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18
Q

What are the 2 mobile carriers in the ETC?

A
  1. Co-enzyme Q (ubiquinone) —> between II and III
  2. Cytochrome C —> between III and IV
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19
Q

Which protein does NADH donate its e-s to?

A

Complex I (NADH dehydrogenase)

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20
Q

Which protein does FADH2 donate its e-s to?

A

Complex II (Succinate dehydrogenase)

21
Q

What happens as e-s pass from each membrane protein to the next?

A

Release energy —> actively transports H+ from matrix to intermembrane space

22
Q

Where does O2 fit into the ETC?

A

Last step
- Complex IV (Cytochrome C oxidase) passes on e-s to O2

23
Q

Why does FADH2 re-oxidation produce less ATP than NADH re-oxidation?

A

Bypasses complex I (NADH dehydrogenase) —> less H+ pumped —> less ATP produced

24
Q

When is FADH2 produced? (3)

A
  1. TCA cycle
  2. B-oxidation
  3. Glycerol-phosphate shuttle (brain and skeletal muscle)
25
What are the 4 redox couples in the ETC?
1. NAD+/NADH 2. FAD+/FADH2 3. Fe3+/Fe2+ 4. 1/2 O2/H20
26
Where is iron present in the ETC?
All proteins and carriers except Q
27
What is redox potential?
Ability of a redox couple to accept/donate e-s
28
What is E0?
Redox potential
29
What does the sign of the E0 indicate?
- +ve ---> accepts e-s (more oxidising than H) - -ve ---> donates e-s (more reducing than H)
30
Why do e-s lose energy as they pass through the ETC?
Reactions are energetically favourable
31
What are the 6 steps of e-s transport in the OxPhos of NADH?
1. NADH dehydrogenase (I) 2. Q (ubiquinone) 3. Q-cytochrome C oxidoreductase (III) 4. Cytochrome C 5. Cytochrome C oxidase (IV) 6. O2 ---> H2O
32
What are the 5 steps in the OxPhos of FADH2?
1. Succinate dehydrogenase (II) 2. Q (ubiquinone) 3. Q-cytochrome C oxidoreductase (III) 4. Cytochrome C 5. Cytochrome C oxidase (IV) 6. O2 ---> H2O
33
What are the 2 parts of ATP synthase and where do they lie?
1. F0 ---> membrane-bound 2. F1 ---> projects into matrix
34
Which 3 subunits does the F0 subunit consist of?
a, b, c
35
Which 3 subunits does the F1 subunit consist of?
a, b, g
36
How can ATP synthase both synthesis and hydrolyse ATP?
1. F1 rotates clockwise ---> H+ into matrix ---> ATP synthesised 2. F1 rotates anticlockwise ---> H+ into intermembrane space ---> ATP hydrolysed - rotations direction controlled by F0
37
How is OxPhos measured in a lab?
Oxygen electrode
38
What is the cathode and anode of an oxygen electrode?
- Platinum cathode - Silver anode
39
What reaction occurs at the cathode of an oxygen electrode?
O2 + 4H+ + 4e- ---> 2 H2O
40
What reaction occurs at the anode of an oxygen electrode?
4 Ag + 4 Cl- ---> 4 AgCl + 4e-
41
Label the 5 features of the [O2] against time graph for an oxygen electrode measuring OxPhos? (Draw)
1. Start 0.25 mM 2. Basal respiration ---> shallow fall 3. ADP added 4. Oxidative Phosphorylation ---> steep fall 5. ADP consumed ---> shallow fall 6. O2 consumed ---> 0mM
42
What are the 6 metabolic poisons affecting OxPhos and where do they act?
1. Rotenone ---> NADH dehydrogenase (I) 2. Malonate ---> Succinate dehydrogenase (II) 3. Cyanide ---> Cytochrome C oxidase (IV) 4. Azide ---> Cytochrome C oxidase (IV) 5. Oligomycin ---> ATP synthase 6. DNP ---> across inner membrane
43
How do cyanide and azide act as metabolic poisons?
CN- and N3- bind to Fe3+ of complex IV (high affinity) ---> block e- flow
44
How does malonate act as a metabolic poison?
-Similar structure to succinate ---> binds to complex II ---> competitive inhibitor
45
How does DNP act as a metabolic poison?
Transport H+ across inner mitochondrial membrane ---> bypasses ATP synthase ---> no ATP generated
46
Which natural physiological process does DNP mimic?
Non-shivering thermogenesis - drop in core temp (eg. in newborns) ---> UCP-1 added to membranes ---> H+ can bypass ATP synthase ---> energy dissipates as heat ---> inc core temp
47
How does rotenone act as a metabolic poison?
Block transfer of e-s from complex I to Q
48
How does oligomycin act as a metabolic poison?
Binds to ATP synthase stalk ---> inhibits ATP synthesis - Antibiotic

1.1 POM Cells (15 decks)

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