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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
Q

What are the 4 redox couples in the ETC?

A
  1. NAD+/NADH
  2. FAD+/FADH2
  3. Fe3+/Fe2+
  4. 1/2 O2/H20
26
Q

Where is iron present in the ETC?

A

All proteins and carriers except Q

27
Q

What is redox potential?

A

Ability of a redox couple to accept/donate e-s

28
Q

What is E0?

A

Redox potential

29
Q

What does the sign of the E0 indicate?

A
  • +ve —> accepts e-s (more oxidising than H)
  • -ve —> donates e-s (more reducing than H)
30
Q

Why do e-s lose energy as they pass through the ETC?

A

Reactions are energetically favourable

31
Q

What are the 6 steps of e-s transport in the OxPhos of NADH?

A
  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
Q

What are the 5 steps in the OxPhos of FADH2?

A
  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
Q

What are the 2 parts of ATP synthase and where do they lie?

A
  1. F0 —> membrane-bound
  2. F1 —> projects into matrix
34
Q

Which 3 subunits does the F0 subunit consist of?

A

a, b, c

35
Q

Which 3 subunits does the F1 subunit consist of?

A

a, b, g

36
Q

How can ATP synthase both synthesis and hydrolyse ATP?

A
  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
Q

How is OxPhos measured in a lab?

A

Oxygen electrode

38
Q

What is the cathode and anode of an oxygen electrode?

A
  • Platinum cathode
  • Silver anode
39
Q

What reaction occurs at the cathode of an oxygen electrode?

A

O2 + 4H+ + 4e- —> 2 H2O

40
Q

What reaction occurs at the anode of an oxygen electrode?

A

4 Ag + 4 Cl- —> 4 AgCl + 4e-

41
Q

Label the 5 features of the [O2] against time graph for an oxygen electrode measuring OxPhos? (Draw)

A
  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
Q

What are the 6 metabolic poisons affecting OxPhos and where do they act?

A
  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
Q

How do cyanide and azide act as metabolic poisons?

A

CN- and N3- bind to Fe3+ of complex IV (high affinity)
—> block e- flow

44
Q

How does malonate act as a metabolic poison?

A

-Similar structure to succinate —> binds to complex II —> competitive inhibitor

45
Q

How does DNP act as a metabolic poison?

A

Transport H+ across inner mitochondrial membrane
—> bypasses ATP synthase —> no ATP generated

46
Q

Which natural physiological process does DNP mimic?

A

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
Q

How does rotenone act as a metabolic poison?

A

Block transfer of e-s from complex I to Q

48
Q

How does oligomycin act as a metabolic poison?

A

Binds to ATP synthase stalk —> inhibits ATP synthesis
- Antibiotic

1.1 pom cells (15 decks)

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