biochemistry 2

Question 1

where does the link reaction take place

Answer 1

mitochondrial matrix

Question 2

what are the 3 stages of the link reaction

Answer 2

1) decarboxylation
2) oxidation
3) transfer to CoA

Question 3

what regulates the pyruvate dehydrogenase complex

Answer 3

• phosphorylation inactivates E1 site
• dephosphorylation activates E1 site
• high energy charge decreases activity and low energy charge increases activity

Question 4

what causes arsenic poisoning

Answer 4

arsenic compounds react with sulfhydryl groups
- inactivates E2

Question 5

how is oxaloacetate converted into citrate and how is it regulated

Answer 5

• additions of acetyl CoA
• regulated by substrate availability
• inhibited by citrate

Question 6

how is citrate used as an inhibitor

Answer 6

inhibitor of phosphofructokinase-1

Question 7

how is citrate converted into isocitrate

Answer 7

• isomerisation by aconitase

Question 8

how is isocitrate converted into alpha-ketaglutarate

Answer 8

• oxidative decarboxylation - removal of CO2
• NAD+ to NADH
• isocitrate dehydrogenase

Question 9

how is alpha-ketoglutarate converted into succinyl CoA

Answer 9

• addition of CoA
• CO2 removed
• NAD+ to NADH
• alpha-ketoglutarate dehydrogenase complex

Question 10

how is succinyl CoA converted to succinate

Answer 10

• succinate thiokinase
• phosphorylation of either GDP to GTP or ADP to ATP

Question 11

how is succinate converted into fumerate

Answer 11

• oxidation - FAD to FADH2
• succinate dehydrognase

Question 12

what does succinate dehydrogenase reduce

Answer 12

flavin adenine dinucleotides
(FAD)

Question 13

how is fumerate converted to malate

Answer 13

• addition of H20
• fumarate hydratase

Question 14

how is malate converted into oxidate

Answer 14

• malate dehydrogenase
• NAD+ to NADH

Question 15

what inhibits citrate synthesis

Answer 15

ATP and citrate

Question 16

what inhibits and activates isocitrate dehydrogenase

Answer 16

• inhibited by ATP
• activated by ADP and NAD+

Question 17

what inhibits alpha-ketoglutarate dehydrogenase complex

Answer 17

• succinyl CoA
• NADH
• ATP

Question 18

what is anaolerotic reactions

Answer 18

• form intermediates to replenish other pathways

Question 19

what does fluroacetate inhibit and cause

Answer 19

• inhibits aconitase
• nausea, vomiting, abdominal pain, sweating, confusion, tachycardia

Question 20

what does arsenate inhibit and cause

Answer 20

• inhibits alpha-ketoglutarate dehydrogenase complex
• drowsiness, headaches, confusion, severe diarrhoea

Question 21

what does malonate inhibit and cause

Answer 21

• inhibits succinate dehydrogenase
• headaches, fatigue, poor appetite, sleeplessness, tremours, confusion, mapped chains, coma, death

Question 22

what does aluminium do to the TCA cycle

Answer 22

• displaces iron
• decreases activity of iron-dependent enzymes and oxidation sensitive enzyme activity

Question 23

what are the iron dependent enzymes

Answer 23

aconitase
succinate dehydrogenase
fumerase
complex IV - electron transport chain

Question 24

what are the oxidation sensitive enzymes

Answer 24

isocitrate dehydrogenase
alpha- ketoglutarate dehydrogenase

Question 25

what is the outer mitochondria membrane permeable to

Answer 25

- small molecules - <10kDa

Question 26

what is the inner mitochondrial membrane impermeable to

Answer 26

- protons - has specialised special transport proteins

Question 27

where are respiratory chains found

Answer 27

- inner membrane - 5 complexes - has adaptors of coenzyme Q and cytochrome C

Question 28

what is the function of respiratory chains

Answer 28

- allows flow of electrons - generate a proton gradient - produces ATP from FADH2 and NADH

Question 29

what does complex I do

Answer 29

- accepts electrons from NADH - passes these onto coenzyme Q

Question 30

what does complex II do

Answer 30

- accepts electrons from FADH2 - passes these onto conezyme Q

Question 31

what does complex III do

Answer 31

- accepts electrons from coenzyme Q - passes these onto cytochrome C

Question 32

what does complex IV do

Answer 32

- accepts electrons from cytochrome C - reduces oxygen to water

Question 33

what does complex V

Answer 33

- protons pass through the channel - movement occurs - drives ATP synthesis

Question 34

what is complex V limited by

Answer 34

- ADP concentration

Question 35

what are the inhibitors of the electron transport chain

Answer 35

- cyanide - CO - rotenone - amytal - abtimycin - oligomycin

Question 36

where do inhibitors bind in the electron transport chain

Answer 36

- binds to chain components - block electron transfer

Question 37

what does arginine react with and form

Answer 37

oxygen to from citruline and NO free radical

Question 38

what do scavenger reactive oxygen species do

Answer 38

- protective enzymes - help neutralise reative oxygen speciles

Question 39

what does superoxide dismutase do

Answer 39

uses copper reactive centre to from intermediates - H2O2 and O2

Question 40

what does peroxidase catalyse do

Answer 40

- uses a iron haem group to form intermediates - 2H2O and O2

Question 41

what do reactive oxygen species do and what are they used for

Answer 41

- highly reactive and damaging - from pollution, smoke, radiation and drugs - used by phagocytes to kill cells

Question 42

what do ionophores do

Answer 42

- activated by free fatty acids - transport protons from the cytosol to matrix

Question 43

what do uncouplers do

Answer 43

- transport protons across the inner mitochondrial membrane into the matrix