Mitochondria Flashcards
The number of mitochondria in healthy cells varies from
200-10,000
Liver cells have how many mitochondria?
~1000
Muscle is a syncytium, meaning
a fused series of cells with thousands of mitochondria
What is the evolutionary nature of mitochondria?
Endosymbiotic bacteria that were incorporated into eukaryotes 2 billion years ago
Acetyl-coA is produced from
pyruvate or fatty acid oxidation (both in mitochondria)
What are the processes carried out by mitochondria?
Acetyl-coA production from pyruvate or fatty acid oxidation, ketone body synthesis (from Acetyl-coA via HMG-coA), TCA cycle, and oxidative phosphorylation
Ketone body synthesis
primary fuel in starvation; metabolite products of fatty acids (acetoacetate, d-B-hydroxybutyrate, acetone)
Fatty acid oxidation occurs where?
occurs in mitochondria, produces Acetyl-coA from fatty acids eg palmitic acid (16c) produces 8 AcoAs for TCA cycle
Reactive oxygen species
are created when e- leak from the ETC; they degrade and destroy mitochondria and other cell components
Mitochondria produce high yields of ATP by
oxidation of fuels (pyruvate or fat) to CO2
What cells in the body lack mitochondria?
red blood cells and retina cells - they are obligated to anaerobic metabolism producing lactate
Ageing can be attributed to
loss of mitochondria and damage by ROS
Mitochondrial diseases are attributed to
mutations in mitochondrial or nuclear DNA
What is the pathological appearance of mitochondrial disease?
ragged red fibres
What are ragged red fibres?
hallmark of mitochondrial disorders; red subsarcolemmal deposits in sections of muscle stained with Gomori trichome
Adipose tissue is signalled to release fatty acids by
adrenaline (FoF) or glucagon
Palmitic acid metabolism yields how many ATP?
~108
What is the role of the urea cycle?
metabolism of nitrogen (NH3) from proteins (amino acids) to urea - occurs in mitochondria
How many grams of protein are required daily?
100g
Adipose tissue releases what in response to adrenaline or glucagon?
glycerol for gluconeogenesis and trigylcerides (FFA) for beta-oxidation in mitochondria
The outer membrane of mitochondria is permeable to
small molecules
The inner membrane of mitochondria is permeable to
nothing without a transporter
Pyruvate enters the inner mitochondrial membrane via
antiport with OH- or symport with H+
Pyruvate is converted to acetyl-coA by
pyruvate dehydrogenase
Each turn of the TCA cycle produces
3NADH, 1FADH2, 1GTP (ATP)
Oxidative phosphorylation occurs at
the inner mitochondrial membrane
Ubiquinone =
Q = coenzyme Q = Q10 = coQ10
What does ATP synthase (ETC) require to function?
an in-tact inner mitochondrial membrane; if the membrane is broken it becomes an ATPase
mtDNA mutations do not affect which respiratory complex?
II - it is encoded on nuclear DNA
How many H+ are pumped per mol NADH?
10 (200kJ/mol)
How many H+ are pumped per mol FADH2?
6 (enters at complex II)
How does ATP synthase generate ATP?
H+ enters the c10 subunit and via charge separations rotates the gamma subunit; this triggers each beta subunit to make ATP from ADP + Pi
What is the role of superoxide dismutase?
generates hydrogen peroxide (H2O2) from O2 radicals which is converted to water by glutathione peroxidase - protective mechanism against ROS
What is uncoupling of oxidative phosphorylation??
leaking of the membrane (eg caused by dinitrophenol) allows H+ to leak out without ATP production - the chain oxidizes NADH but produces no ATP
NADH generates how many ATP?
2.5
FADH2 generates how many ATP?
1.5
Glucose generates how many ATP?
32
What is the function of the malate-aspartate shuttle?
transfers the reducing power of NADH from cytosol to mitochondria for oxidative phosphorylation; generates 32 ATP per glucose
What is the function of the glycerol-3-phosphate shuttle?
operates in muscle, dumps reducing power of NADH right into complex II via FADH2; generates 30 ATP per glucose
Malate-aspartate shuttle results in how many ATP per glucose?
32
Glycerol-3-phosphate shuttle results in how many ATP per glucose?
30
