TCA Cycle Flashcards
What happens to pyruvate in aerobic conditions?
converts to acetyl coenzyme A
what does Acetyl CoA do?
Links glycolysis from cytoplasm to krebs in matrix of mitochondria
What cells lack mitochondria?
RBC - only perform glycolysis
What is each pyruvic acid converted to?
2 carbon acetyl group
How is acetyl coA made?
remove 1 molecule of co2 as waste so NAD+ to NADH
What is the net gain from glycolysis and link reaction?
2 ATP - 4 NADH - 2 Acetyl coA
What is pyruvate dehydrogenase deficiency?
sex linked disease
build up of lactic acid in body (lactic acidosis)
nausea vomiting - neuro problems
What occurs in krebs cycle?
Redox and decarboxylation reactions
What do redox reactions do?
Transfer energy to NAD and FAD
How many ATP molecules in krebs?
12 ATP - 24 per glucose
What does acetyl group in krebs cycle do?
Generates 6 carbon molecule citrate - coA recycled
What does acetyl group entry create?
citrate and regenerates coA
What happens to citrate?
Isomerisation to isocitric acid
Where does oxidative decarboxylation occur?
Remove CO2 and forms NADH and alphae ketoglutarate from isocitrate dehydrogenase
Where does substrate level phosphorylation occur?
from succinyl coA displaced for phosphate transferred to GDP and donated to ATP forms succinate
Where does dehydration occur?
succinate oxidised to furmarate by FADH2 formation
Where does hydration occur?
Furmurate converted to malate by adding water
What does dehydrogenation do?
converts to oxaloacetate and forms NADH
Which enzyme allows substrate level phosphorylation?
succinyl coA synthetase
What does regulation of TCA depend on?
substrate availability
inhibition by product accumulation
allosteric inhibition
What is citrate synthase inhibited by?
Citrate and ATP
What is isocitrate dehydrogenase inhibited by?
NADH and ATP activated by ADP
What is Alpha ketoglutarate dehydrogenase inhibited by?
NADH and succinyl coA
How is TCA regulated?
Pyruvate dehydrogenase inhibited by NADH and acetyl coA
What regulates the enzyme in TCA?
pyruvate dehydrogenase kinase and phosphatase
What is ATP used for in TCA?
phosphorylate a key SER residue to inactivate the enzyme
What is kinase activated by?
ATP, NADH, acetyl coA
What inhibits kinase in TCA?
Pyruvate
What happens in Arsenic poisoning?
headaches, confusion, drowsiness - convulsions occur - organs affected are skin and kidney and liver - allosteric inhibition of essential metabolic enzyme PDH complex
What is the ETC?
series of electron carriers - as electrons pass through chain exergonic reactions release energy used to form ATP
What is chemiosmosis?
Links chemical reactions with pumping of H+ ions - final electron acceptor is oxygen to form water
What is flavin mononucloetides?
Flavoprotein - vitamin B2
What are cytochromes?
Proteins with iron containing group can exist in reduced Fe2 and oxidised Fe3 form
What do iron-sulfur centres?
contain 2 or 4 iron atoms bound to sulfur atoms - forms electron transfer centre
What are copper atoms bound to?
2 proteins in the chain participate in electron transfer
What is coenzyme Q?
is a non-protein carrier in lipid bilayer
Where do electrons pass from?
NADH TO NADH reductase - electrons accepted by FMN then passed to iron clusters
Where are Electrons passed to?
coenzyme Q 0 ubiquinone - shuttles electrons to cytochrome reductase
Where are Electrons next shuttled by cytochrome c?
to cytochrome oxidase copper converted to Cu+
What does cytochrome c oxidase pass?
pass 4 electrons to molecular oxygen to form 2 molecules of water
How many molecules of ATP generated in ETC?
32 or 34
What made in glycolysis that cant enter mitochondria?
NADH
What does NADH do?
Donate electrons to malate or glycerol phosphate shuttle
What organs use malate shuttles and how many ATPs?
3 ATP molecules
Liver, kidney, heart
What shuttle does rest of body use?
glycerol phosphate shuttle - 2 ATP molecules FAD as H acceptor
What does NADH from cytosol give 2 electrons to?
DHAP - dihydroxyacetone phosphate to form glycerol-3-phosphate
What does Glyc-3-phos bind to?
Inner membrane dehydrogenase which has FAD prosthetic group
What does G3P transfer its electrons to?
FAD prosthetic group - CoQ binds to FAD to take electron to ETC to cytochrome reducate
What is cytosolic NADH electrons equivalent to?
Mitochondria generated FAD electrons
How many ATPs from glycolysis?
oxidation of glucose to pyruvic acid molecules = 2 ATP substrate level phosphorylation
Production of 2 NADH + 2H - 4-6 ATP oxidative phosphorylation
How many ATPs in Link reaction?
6 ATP from oxidative phosphorylation - 2 NADH and 2 H
How many ATP from krebs and ETC?
Oxidation of succinyl coA to succinic acid = 2 GTPs to atp
Production of 6NADH % h = 18 Oxidative ATP
Production of 2 FADH - 4 Oxidative ATPS
Total ATP per glucose molecule?
36-38
