Energy Production Flashcards
Pyruvate dehydrogenase activated and inhibited by
Activated: pyruvate, coASH, NAD+, ADP, insulin
Inhibited: acetyl-CoA, NADH, ATP, citrate
Electron transport
Electrons on NADH and FAD2H transferred through a series
of carrier molecules to oxygen
Oxidative phosphorylation
Free energy released used to drive ATP synthesis
Proton motive force (pmf)
[H+] gradient (membrane potential) across inner mitochondrial
membrane
Do electrons in NADH or FADH2 have more energy? How many PTCs do they use?
NADH
NADH uses 3 and FADH2 uses 2
How many moles of ATP is produced from two moles of NADH and FADH2?
NADH synthesis of 5 moles of ATP (P/O = 2.5)
FADH2 synthesis of 3 moles of ATP (P/O = 1.5)
How does cyanide inhibit the electron transport chain?
Prevents acceptance of electrons by O2
Inhibitors of the electron transport chain
Cyanide and carbon monoxide
Block flow of electrons, no pmf
Uncouplers
Dinitrophenol, dinitrocresol, fatty acids
Increase permeability of membrane to H+
H+ enters mitochondria without driving ATP synthetase
Dissipates p.m.f.
Ox/Phos diseases
Genetic defects in proteins encoded by mtDNA
Decrease in electron transport and ATP synthesis
Extra heat generation in brown adipose tissue
Thermogenin (UCP1)
In response to noradrenaline, lipase releases fatty acids from triacylglycerol. Oxidised fatty acids activate UCP1. Electron Transport uncoupled from ATP Synthesis. Energy of p.m.f. is then released as extra heat.
Which vitamins cannot be synthesised in the body?
A D E K
What is triacylglycerol made from?
Glycerol and fatty acids
What do chylomicrons contain?
Fatty acids
Hormone sensitive lipase in lipid metabolism stimulated and inhibited by…
Stimulated by glucagon and adrenaline
Inhibited by insulin
What is used to transport fatty acids across the mitochondria membrane?
Carnitine shuttle
Classes of lipids
Fatty acid derivatives
Hydroxy-methyl-glutaric acid derivatives
Vitamins
Which processes produce and break down triacylglycerol?
Esterification and lipolysis
What do chylomicrons transport?
Dietary triacylglycerol
How are TAG released and transported in the circulation?
Lymphatics
Albumin fatty acid complex
Fatty acid catabolism
Fatty acids activated by linking to coenzyme A
Transported across inner membrane using carnitine shuttle
Cycles through sequence of oxidative reactions, with C2 removed each time
FADH2 and NADH+H produced
What links fatty acids to coenzyme A?
Fatty acyl CoA synthase
When is carnitine shuttle transport inhibited and by what?
When energy levels are high
By malonyl CoA
In which tissues does beta oxidation not occur?
Brain, RBC and WBC
What does fatty metabolism stop in the absence of?
Oxygen
What are the three ketone bodies produced in the body?
Acetoacetate
Acetone
Beta hydroxybutyrate
What is the normal plasma body concentration? Starvation concentration? Concentration with untreated type 1 diabetes?
Normal <1 mM
Starvation 2-10 mM physiological ketosis
Type 1 diabetes >10 mM pathological ketosis
Which enzyme converts HMG to mevalonate and in turn cholesterol?
HMG CoA reductase
How is ketone body production controlled in the liver?
Low NAD substrate availability and high NADH inhibits enzymes isocitrate dehydrogenase and alpha ketoglutarate dehydrogenase. Acetylcholine diverted from TCA cycle
Which enzymes in ketone synthesis are inhibited and which are activated when the insulin:glucagon ratio is high?
Lyase is inhibited
Reductase is activated
Therefore cholesterol synthesis
Which enzymes in ketone synthesis are inhibited and which are activated when the insulin:glucagon ratio is low?
Lyase is activated
Reductase is inhibited
Therefore ketone body synthesis
What is ketonuria and ketoacidosis?
Ketonuria: high ketones in blood
Ketoacidosis: acetoacetate and beta hydroxybutyrate are strong organic acids so cause acidosis
