Mitochondrial synthesis of ATP

Question 1

what is the approximate concentration of ATP in cells

Answer 1

6mM

Question 2

what is the turnover of ATP per day?

Answer 2

75kg/day

Question 3

how much of the energy from food produces ATP?

Answer 3

around 1/2

Question 4

what is the permeability of the outer membrane of mitochondria to substances?

Answer 4

freely permeable if

Question 5

what is characteristic of the inner mitochondrial membrane?

Answer 5

cristae!

Question 6

what does the inner membrane of mitochondria control?

Answer 6

entry/ exit of molecules

Question 7

what sort of insulator is the inner membrane of mitochondria?

Answer 7

electrical insulator

by controlling movement of ions

Question 8

what types of transporters are within the inner membrane of mitchondria?

Answer 8

more protein than lipid transporters

Question 9

what is the concentration of metabolites and ions like in the intermembrane space of mitochondria?

Answer 9

similar to cytosol

Question 10

what substances are found within the matrix of mitochondria?

Answer 10

lots of enzymes
high concentration of substrates, cofactors, ions
mitochondrial DNA, RNA, ribosomes (most proteins encoded on nuclear DNA)

Question 11

where does the link reaction occur?

Answer 11

matrix of mitchondria

Question 12

what happens to pyruvate in the link reaction?

Answer 12

becomes acetyl coA

Question 13

what is the key decision point of the link reaction and why?

Answer 13

pyruvate dehydrogenase

Question 14

what inhibits the link reaction?

Answer 14

high energy levels so high ratio of NADH: NAD and high ratio of ATP: ADP and high levels of acCOa

Question 15

what happens to NAD in the link reaction?

Answer 15

reduced to NADH

Question 16

which cofactor is required for pyruvate dehydrogenase?

Answer 16

B1/ thiamin

Question 17

what does B1/thiamin deficiency result in?

Answer 17

neurological problems/ cardiovascular symptoms

in alcohol addicts –> Wernicke Korsakoff syndrome

Question 18

where does the krebs/ citric acid cycle take place?

Answer 18

mitochondria matrix

Question 19

what activates pyruvate dehydrogenase enzyme?

Answer 19

high levels of Ca signalling sudden demand for energy

Question 20

which 3 enzymes are key to the krebs cycle?

Answer 20

citrate synthese, isocitrate dehydrogenase, a-ketoglutarate dehydrogenase

Question 21

what happens during stage 1 of the krebs cycle?

Answer 21

acetyl coA –> 6C citrate –> 4C succinyl coA + 2CO2

Question 22

how many CO2 molecules are released in the 1st stage of the krebs cycle?

Answer 22

2 CO2

Question 23

what happens during the 2nd stage of the krebs cycle?

Answer 23

oxidation of 4C compound –> oxaloacetate

Question 24

what are the products of the krebs cycle?

Answer 24

3NADH, FADH2, 2CO2, GTP,

Question 25

what percentage of cellular ATP is produced in mitochondria under aerobic conditions?

Answer 25

95%

Question 26

what does the concentration of intermediates in the krebs cycle depend on?

Answer 26

other reactions in the cell

Question 27

what are intermediates in the krebs cycle exchanged for?

Answer 27

other metabolic pathways

Question 28

which pathways may use krebs cycle intermediates as building blocks?

Answer 28

anabolic/ synthetic pathways

Question 29

why does ketone synthesis occur in DMT1?

Answer 29

glycolysis inhibited, low pyruvate oxaloacetate and malate removed from the krebs cycle to be used in gluconeogenesis fatty acids oxidised for energy --> XS acteyl CoA because of lack of oxaloacetate therefore broken down into ketones --> ketoacidosis

Question 30

which 2 processes are tightly coupled in oxidative phosphorylation?

Answer 30

electron transport and ATP synthesis

Question 31

what happens during electron transport?

Answer 31

oxidation

Question 32

what happens during ATP synthesis?

Answer 32

phosphorylation

Question 33

what does the electron transport create?

Answer 33

proton gradient

Question 34

what does ATP synthesis require?

Answer 34

proton gradient

Question 35

which 2 cofactors are involved in electron transport?

Answer 35

NADH and FADH2

Question 36

what supplies energy to electron transport?

Answer 36

electrons

Question 37

what supplies energy to ATP synthesis (in oxidative phosphorylation?

Answer 37

proton gradient

Question 38

how many complexes are involved in electron transport?

Answer 38

4 (I, II, III, IV)

Question 39

which complexes are transmembrane?

Answer 39

I, III, IV

Question 40

what are the 2 other electron carriers in the membrane needed for electron transport?

Answer 40

ubiquinone, cytochrome C

Question 41

which complex does NADH give an H to?

Answer 41

complex I

Question 42

which complex does FADH2 give H to?

Answer 42

complex II

Question 43

what is the final electron acceptor of the electron transport chain?

Answer 43

oxygen

Question 44

what happens to oxygen in the electron transport chain?

Answer 44

combines with electrons and 2 protons --> water

Question 45

where does cyanide inhibit electron transport?

Answer 45

blocks the reduction of oxygen to water

Question 46

where does oxidative phosphorylation occur in the mitochondria?

Answer 46

across the inner mitochondrial membrane (well insulated membrane)

Question 47

where is the concentration of H lower in mitochondria?

Answer 47

in the matrix

Question 48

which complexes translocate H across the membrane?

Answer 48

I, III, IV

Question 49

which direction are H ions translocated?

Answer 49

from matrix into intermembrane space

Question 50

how many H are translocated per NADH?

Answer 50

4

Question 51

why does FADH2 cause fewer H to be translocated?

Answer 51

it releases electrons into the electron transport chain later than NADH

Question 52

What does the F0F1 ATPase do?

Answer 52

synthesises ATP

Question 53

What is the name of the antiporter that transports ADP and ATP?

Answer 53

adenine nucleotide transporter

Question 54

Which other transporters exists in addition to F0F1ATPase and adenine nucleotide transporter?

Answer 54

Pi and H

Question 55

how many H move through ATPase?

Answer 55

3

Question 56

why does the movement of H down the conc gradient cause ATP to be produced?

Answer 56

it causes physical movement pushing the proteins around like a motor

Question 57

which direction does ATP move through the antiporter and why?

Answer 57

matrix into intermembrane space so ATP can be released and used!

Question 58

Why does one H move through the transporter as one Pi moves into the matrix?

Answer 58

to maintain electroneutrality as Pi is negatively charged

Question 59

why can ATP synthesis not occur without electron transport?

Answer 59

electron transport required to set up the proton gradient

Question 60

why might there be a problem with ATPase?

Answer 60

lack of ADP

Question 61

why might electron transport be inhibited?

Answer 61

lack of oxygen or reduced cofactor substrates

Question 62

why does a problem with ATPase stop electron transport?

Answer 62

H concentration builds up in intermembrane space so H can move down concentration gradient through complexes

Question 63

how many H move across the inner mitochondrial membrane to the matrix per 1 ATP synthesised?

Answer 63

4 (3 through synthase 1 through H transporter)

Question 64

what are uncouplers?

Answer 64

weak acids

Question 65

what happens in uncoupling?

Answer 65

uncouple oxidation from phosphorylation

Question 66

what effect do uncouplers have on the H gradient?

Answer 66

dissipates

Question 67

what happens to electron transport and ATP synthesis?

Answer 67

electron transport can continue but ATP synthesis inhibited

Question 68

which natural uncoupler protein exists in mitochondria in brown adipose tissue?

Answer 68

thermogenin

Question 69

what is energy released as in brown adipose tissue?

Answer 69

heat

Question 70

what activates thermogenin in brown adipose tissue?

Answer 70

decrease in core body temp, increase in NA released, increase in fatty acids in cytosol, activates thermogenin