FORM & FUNCTION (TCA cycle and ETC)

Question 1

acetyl-CoA formation

Answer 1

-pyruvate is the end product of glycolysis and is transported into the mitochondria
-conversion to acetyl-CoA by pyruvate dehydrogenase
*irreversible
*also get 2 CO2 formed

Question 2

tricarboxylic acid cycle

Answer 2

-acetyl-CoA (2C), combines with oxaloacetate (4C) to form citrate and initate the TCA cycle

Question 3

each TCA cycle generates

Answer 3

-3NADH
-1FADH2
-1 GTP
-2 CO2
*2 cycles per glucose

Question 4

why does H+ fluctate?

Answer 4

1. From cell metabolism
2. Anaerobic metabolism

Question 5

cell metabolism (H+ fluctuate)

Answer 5

-TCA cycle
-aerobic
-Ex. 1 glucose to pyruvate to 3 CO2 (x2)
*6 CO2 produced per glucose aerobically metabolized

Question 6

anaerobic metabolism (H+ fluctuate)

Answer 6

-genreates lactic acid
-increase H+, decrease HCO3-

Question 7

NADH & FADH2

Answer 7

-energy rich molecules (‘electron carriers’)
-synthesized from micronutrients
-both can change from oxidized form to reduced form (reduced=carrying electrons)
*both carry 2 electrons

Question 8

electron transport chain

Answer 8

-in the inner mitochondria membrane
-NADH and FADH2 are fed into it
-electrons flow from matrix to intermembrane space

Question 9

NADH ETC

Answer 9

-oxidized by complex I (generates 2 electrons, 1 proton)
-electrons are transported inside complex I
>generates energy which is used to pump the H+ from the matrix to the intermembrane space

Question 10

FADH2 ETC

Answer 10

-oxidized by complex 2
-electron transport takes place but no H+ is pumped out
(complex doesn’t go all the way through the membrane)

Question 11

NAD+ and FAD+

Answer 11

-will be recycled back into TCA cycle after they drop their electrons and H+ in the ETC
*while TCA doesn’t require oxygen, oxygen in ETC is required to replenish them

Question 12

iron sulfur clusters

Answer 12

-core component of ETC
-apart of complex I, II and III
-‘carries’ electrons
*small amount of energy is released each time an electron is passed=drives proton pumping

Question 13

electrons transported

Answer 13

-continued to be transported to complex III (coenzymeQ), and complex IV (cytochrome C)
*pumps more H+ in the process=builds up the proton gradient between the membrane

Question 14

complex IV

Answer 14

-electrons are coupled with oxygen and protons inside mitochondrial matrix creates water
-removal of matrix proton further strengthens the electrochemical (proton) gradient across the membrane
*oxygen is final electron acceptor=aerobic respiration
*no oxygen=electron is stuck in complex IV=’back up of electrons’

Question 15

electrochemical (proton) gradient

Answer 15

-drive proton back into mitochondria through ATP synthase, generating energy required to phosphorylate ADP to ATP
-1 ATP for 1 proton
-like a wind turbine or dam generating electricity

Question 16

ATP per NADH and FADH2

Answer 16

1. NADH=3 protons=3ATP
2. FADH2=2 protons=2ATP

Question 17

TCA & ETC inhibitors

Answer 17

1. Rotenone
2. Cyanide
3. Fluoroacetate

Question 18

rotenone

Answer 18

-found naturally in plans
-interferes with iron cluster in complex I of ETC=prevents transfer of electron to conenzyme Q
-widely used as pesticide, insectiside

Question 19

rotenone used to

Answer 19

-treat parasitic mites on chickens and fowl, lice and ticks in dogs
-highly toxic to insects and fish, lower toxicity in mammals

Question 20

cyanide

Answer 20

-naturally found in plants
-bind irreversibly to iron cluster in complex IV=prevent final transport of electrons to oxygen to form water molecules
-stalls entire ETC as electrons are ‘stuck’ at previous complexes

Question 21

cyanide used for

Answer 21

-highly poisonous
-heart and brain are most susceptible due to reliance on aerobic respiration

Question 22

fluroacetate

Answer 22

-found naturally in plants
-strongly binds to aconitas, competing with citrate, stalls TCA cycle with citrate accumulation
-inhibits production of NADH and FADH2 for ETC

Question 23

fluroacetate used for

Answer 23

-tasteless, odourless, used for bait to eradicate invasive wildlife in Australia and New Zealand
-used as controlled rodenticide in other countries

Question 24

ATP production aerobic

Answer 24

-much more efficient
-38 ATP and 6xCO2

Question 25

ATP production anaerobic

Answer 25

-2 ATP
-2 NADH: not used
-2 pyruvate: go to lactate
*fast twitch muscles can only rely on it for quick contraction, but cannot sustain it over time (lactate build up=metabolic acidosis)