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Metabolism > Mitochondria > Flashcards

Mitochondria Flashcards

1
Q

The number of mitochondria in healthy cells varies from

A

200-10,000

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2
Q

Liver cells have how many mitochondria?

A

~1000

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3
Q

Muscle is a syncytium, meaning

A

a fused series of cells with thousands of mitochondria

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4
Q

What is the evolutionary nature of mitochondria?

A

Endosymbiotic bacteria that were incorporated into eukaryotes 2 billion years ago

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5
Q

Acetyl-coA is produced from

A

pyruvate or fatty acid oxidation (both in mitochondria)

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6
Q

What are the processes carried out by mitochondria?

A

Acetyl-coA production from pyruvate or fatty acid oxidation, ketone body synthesis (from Acetyl-coA via HMG-coA), TCA cycle, and oxidative phosphorylation

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7
Q

Ketone body synthesis

A

primary fuel in starvation; metabolite products of fatty acids (acetoacetate, d-B-hydroxybutyrate, acetone)

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8
Q

Fatty acid oxidation occurs where?

A

occurs in mitochondria, produces Acetyl-coA from fatty acids eg palmitic acid (16c) produces 8 AcoAs for TCA cycle

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9
Q

Reactive oxygen species

A

are created when e- leak from the ETC; they degrade and destroy mitochondria and other cell components

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10
Q

Mitochondria produce high yields of ATP by

A

oxidation of fuels (pyruvate or fat) to CO2

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11
Q

What cells in the body lack mitochondria?

A

red blood cells and retina cells - they are obligated to anaerobic metabolism producing lactate

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12
Q

Ageing can be attributed to

A

loss of mitochondria and damage by ROS

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13
Q

Mitochondrial diseases are attributed to

A

mutations in mitochondrial or nuclear DNA

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14
Q

What is the pathological appearance of mitochondrial disease?

A

ragged red fibres

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15
Q

What are ragged red fibres?

A

hallmark of mitochondrial disorders; red subsarcolemmal deposits in sections of muscle stained with Gomori trichome

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16
Q

Adipose tissue is signalled to release fatty acids by

A

adrenaline (FoF) or glucagon

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17
Q

Palmitic acid metabolism yields how many ATP?

A

~108

18
Q

What is the role of the urea cycle?

A

metabolism of nitrogen (NH3) from proteins (amino acids) to urea - occurs in mitochondria

19
Q

How many grams of protein are required daily?

A

100g

20
Q

Adipose tissue releases what in response to adrenaline or glucagon?

A

glycerol for gluconeogenesis and trigylcerides (FFA) for beta-oxidation in mitochondria

21
Q

The outer membrane of mitochondria is permeable to

A

small molecules

22
Q

The inner membrane of mitochondria is permeable to

A

nothing without a transporter

23
Q

Pyruvate enters the inner mitochondrial membrane via

A

antiport with OH- or symport with H+

24
Q

Pyruvate is converted to acetyl-coA by

A

pyruvate dehydrogenase

25
Q

Each turn of the TCA cycle produces

A

3NADH, 1FADH2, 1GTP (ATP)

26
Q

Oxidative phosphorylation occurs at

A

the inner mitochondrial membrane

27
Q

Ubiquinone =

A

Q = coenzyme Q = Q10 = coQ10

28
Q

What does ATP synthase (ETC) require to function?

A

an in-tact inner mitochondrial membrane; if the membrane is broken it becomes an ATPase

29
Q

mtDNA mutations do not affect which respiratory complex?

A

II - it is encoded on nuclear DNA

30
Q

How many H+ are pumped per mol NADH?

A

10 (200kJ/mol)

31
Q

How many H+ are pumped per mol FADH2?

A

6 (enters at complex II)

32
Q

How does ATP synthase generate ATP?

A

H+ enters the c10 subunit and via charge separations rotates the gamma subunit; this triggers each beta subunit to make ATP from ADP + Pi

33
Q

What is the role of superoxide dismutase?

A

generates hydrogen peroxide (H2O2) from O2 radicals which is converted to water by glutathione peroxidase - protective mechanism against ROS

34
Q

What is uncoupling of oxidative phosphorylation??

A

leaking of the membrane (eg caused by dinitrophenol) allows H+ to leak out without ATP production - the chain oxidizes NADH but produces no ATP

35
Q

NADH generates how many ATP?

A

2.5

36
Q

FADH2 generates how many ATP?

A

1.5

37
Q

Glucose generates how many ATP?

A

32

38
Q

What is the function of the malate-aspartate shuttle?

A

transfers the reducing power of NADH from cytosol to mitochondria for oxidative phosphorylation; generates 32 ATP per glucose

39
Q

What is the function of the glycerol-3-phosphate shuttle?

A

operates in muscle, dumps reducing power of NADH right into complex II via FADH2; generates 30 ATP per glucose

40
Q

Malate-aspartate shuttle results in how many ATP per glucose?

A

32

41
Q

Glycerol-3-phosphate shuttle results in how many ATP per glucose?

A

30

Metabolism (16 decks)

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