Mitochondria

Question 1

The number of mitochondria in healthy cells varies from

Answer 1

200-10,000

Question 2

Liver cells have how many mitochondria?

Answer 2

~1000

Question 3

Muscle is a syncytium, meaning

Answer 3

a fused series of cells with thousands of mitochondria

Question 4

What is the evolutionary nature of mitochondria?

Answer 4

Endosymbiotic bacteria that were incorporated into eukaryotes 2 billion years ago

Question 5

Acetyl-coA is produced from

Answer 5

pyruvate or fatty acid oxidation (both in mitochondria)

Question 6

What are the processes carried out by mitochondria?

Answer 6

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

Question 7

Ketone body synthesis

Answer 7

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

Question 8

Fatty acid oxidation occurs where?

Answer 8

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

Question 9

Reactive oxygen species

Answer 9

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

Question 10

Mitochondria produce high yields of ATP by

Answer 10

oxidation of fuels (pyruvate or fat) to CO2

Question 11

What cells in the body lack mitochondria?

Answer 11

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

Question 12

Ageing can be attributed to

Answer 12

loss of mitochondria and damage by ROS

Question 13

Mitochondrial diseases are attributed to

Answer 13

mutations in mitochondrial or nuclear DNA

Question 14

What is the pathological appearance of mitochondrial disease?

Answer 14

ragged red fibres

Question 15

What are ragged red fibres?

Answer 15

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

Question 16

Adipose tissue is signalled to release fatty acids by

Answer 16

adrenaline (FoF) or glucagon

Question 17

Palmitic acid metabolism yields how many ATP?

Answer 17

~108

Question 18

What is the role of the urea cycle?

Answer 18

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

Question 19

How many grams of protein are required daily?

Answer 19

100g

Question 20

Adipose tissue releases what in response to adrenaline or glucagon?

Answer 20

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

Question 21

The outer membrane of mitochondria is permeable to

Answer 21

small molecules

Question 22

The inner membrane of mitochondria is permeable to

Answer 22

nothing without a transporter

Question 23

Pyruvate enters the inner mitochondrial membrane via

Answer 23

antiport with OH- or symport with H+

Question 24

Pyruvate is converted to acetyl-coA by

Answer 24

pyruvate dehydrogenase

Question 25

Each turn of the TCA cycle produces

Answer 25

3NADH, 1FADH2, 1GTP (ATP)

Question 26

Oxidative phosphorylation occurs at

Answer 26

the inner mitochondrial membrane

Question 27

Ubiquinone =

Answer 27

Q = coenzyme Q = Q10 = coQ10

Question 28

What does ATP synthase (ETC) require to function?

Answer 28

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

Question 29

mtDNA mutations do not affect which respiratory complex?

Answer 29

II - it is encoded on nuclear DNA

Question 30

How many H+ are pumped per mol NADH?

Answer 30

10 (200kJ/mol)

Question 31

How many H+ are pumped per mol FADH2?

Answer 31

6 (enters at complex II)

Question 32

How does ATP synthase generate ATP?

Answer 32

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

Question 33

What is the role of superoxide dismutase?

Answer 33

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

Question 34

What is uncoupling of oxidative phosphorylation??

Answer 34

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

Question 35

NADH generates how many ATP?

Answer 35

2.5

Question 36

FADH2 generates how many ATP?

Answer 36

1.5

Question 37

Glucose generates how many ATP?

Answer 37

32

Question 38

What is the function of the malate-aspartate shuttle?

Answer 38

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

Question 39

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

Answer 39

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

Question 40

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

Answer 40

32

Question 41

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

Answer 41

30