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Biology Of Ageing Year2 > Mitochondrial structure and function > Flashcards

Mitochondrial structure and function Flashcards

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1
Q

What is the structure of the Mitochondrial DNA (mtDNA)?

A

Covalently-closed DNA molecule (16.6 kb).

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2
Q

Where is the Mitochondrial DNA (mtDNA)?

A

Located in mitochondrial matrix.

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3
Q

How much Mitochondrial DNA (mtDNA) is in the cell?

A

Multiple copies per cell

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4
Q

What is the make-up of Mitochondrial DNA (mtDNA)?

A
  • 13 protein-encoding genes
  • 2 rRNAs
  • 22 tRNAs
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5
Q

What is glycolysis?

A

Glucose is broken down into pyruvate.

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6
Q

What does the krebs cycle produces?

A

FADH2 and NADH.

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7
Q

What is the function of FADH and NADH?

A

Carry the electrons needed for respiration.

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8
Q

Draw the process of beta-oxidation of fatty acids.

A
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9
Q

What is the OXPHOS process split into?

A

Electron transport chain. ( complex1-4)

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10
Q

What happens during the OXPHOS process?

A

Protons are donated by the NADH and the FADH which drives a proton gradient to travel across the matrix to the intermembrane space creating an electrochemical gradient. ATP synthase allows the protein to flow back and create ATP.

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11
Q

Which OXPHOS enzyme is the largest?

A

Complex 1

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12
Q

What is the structure of complex 1?

A

Has a hydrophobic arm (protrudes into the mitochondrial matrix) and a hydrophilic arm (sits within the mitochondrial membrane).

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13
Q

How many subunits does complex 1 contain?

A

45

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14
Q

How many subunits in complex 1 is encoded by mitochondria DNA?

A

7

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15
Q

How many subunits are encoded by nuclear DNA?

A

38

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16
Q

What is the function of complex 1?

A

The first entry point for electrons into the TCA cycle, NADH is oxidised, and electrons are passed through sulphur clusters until it reaches ubiquinone.

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17
Q

What happen during the reactions occur at complex 1?

A

Protons pumped into the intermembrane space.

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18
Q

What is Q?

A

Coenzyme.

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19
Q

What is QH2?

A

Reduced CoQ or Ubiquinol.

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20
Q

What is the net transfer of protons during the reactions in complex 1?

A

4 protons from the inside to the outside. contributes to electrochemical gradient.

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21
Q

What is the name for complex 2?

A

Succinate dehydrogenase.

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22
Q

Which of the complexes in the OXPHOS cycle are the smallest/

A

Complex 2

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23
Q

How many subunits is complex 2 made up of?

A

4.

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24
Q

What subunits is complex 2 or succinate dehydrogenase made up of?

A

SDH (A,D,C AND D).

25
Q

What kind of DNA encodes for complex 2?

A

Nuclear, no mitochondrial.

26
Q

What is unique about complex 2?

A

Takes part in both the krebs cycle and the electron transport chain.

27
Q

Where is SDHA?

A

Hydrophilic so it is inside the matrix.

28
Q

Where is SDHB?

A

Hydrophilic so it is inside the matrix.

29
Q

Where is SDHC?

A

Hydrophobic so integral membrane proteins.

30
Q

Where is SDHC?

A

Hydrophobic so integral membrane proteins.

31
Q

Where is SDHD?

A

Hydrophobic so integral membrane proteins.

32
Q

What is the function of complex 2?

A

Catalyses the oxidation of succinate to fumarate.

33
Q

How does the complex 2 oxidate succinate?

A

FAD is reduced.

Electrons from FADH2 transferred to ubiquinone via the iron sulphur clusters in SDHB reducing it.

QH2 passes electrons to carriers.

34
Q

What is the net proton transfer of complex 2?

A

0, doesn’t contribute to the electrochemical gradient at all.

35
Q

What is the name of complex 3?

A

Ubiquinol : cytochrome C oxidoreductase

36
Q

How many monomers is complex 3 made up of?

A

2 it is a functional dimer.

37
Q

How many subunits does each of the monomers in complex 3 have?

A

11.

38
Q

How many subunits are encoded by mitochondial DNA?

A

1 per monomer, the rest is nuclear DNA.

39
Q

What is the function of complex 3?

A

It goes through the q cycle.

40
Q

What is the Q cycle?

A

In the first half cycle, the ubiquinol molecule attaches on to complex 3 one electron transfers to the iron sulphur cluster and the other attaches to cytochrome 3 this forms a quinol radical.

In the other half cycle, another molecule of ubiquinol follows the pathway

41
Q

What is the result of the Q cycle?

A

The oxidation of ubiquinol (QH2) to ubiquinone (Q)
The reduction of cytochrome c.

42
Q

How many subunits does complex 4 contain?

A

14

43
Q

Which subunits in complex 4 are encoded by the mitochondrial DNA?

A

1 to 3

44
Q

Which subunits in complex 4 are encoded by the nuclear DNA?

A

4- 14

45
Q

What does Compex 4 contain?

A

2 non-covalently bound haem and copper centres for electron transfer.

46
Q

What is the function of complex 4?

A

Electron transfer.

47
Q

How does complex 4 transfer electrons?

A

Oxidation of 4 molecules of cytochrome c
The passes the electrons to copper centres
Then passes to iron sulphur clusters and reduces oxygen to water.

48
Q

What is the net transfer in complex 4?

A

4 protons being pumped and 2 molecules of water being made.

49
Q

What is complex 5 also known as?

A

ATP synthase.

50
Q

How many subunits does complex 5 have?

A

16

51
Q

How many of the complex 5 subunits are encoded by mitochondrial DNA?

A

2, the other 14 are nuclear.

52
Q

What are the 2 main domains present in complex 5?

A

Fo domain
F1 domain.

53
Q

What is the f0 domain?

A

Contains proton channel, additional subunits and C ring subunits

54
Q

What is the f1 domain?

A
  • active site for ATP synthesis
  • protrudes into the matrix
55
Q

What is classed as the central stalk within the f1 domain in complex 5?

A

One γ, ᵯ , and ᵰ subunits

56
Q

What is classed as the peripheral stalk within the f1 domain in complex 5?

A

Subunits b, d, F6 and OSCP

57
Q

What is the function of complex 5 (ATP synthase)?

A

Harness energy stored in proton gradient.

58
Q

How does ATP synthase (complex 5)?

A

Together, the c-ring and additional subunits create a proton channel.
Protons move across the inner mitochondrial membrane down the electrochemical gradient.
Protons enter the F0 sub-complex.
As the protons cause rotation of the c-ring
Central stalk rotates
This results in conformational changes that enable the access of ADP + Pi and the release of the ATP.

Biology Of Ageing Year2 (23 decks)

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