Week 6 Flashcards
What does pyruvate dehydrogenase require as a cofactor?
PDH requires thiamine pyro phosphate as a co factor.
What is the link reaction?
Pyruvate to acetyl CoA through pyruvate dehydrogenase.
What is thiamine pyro phosphate ?
A lack of thiamine disrupts pyruvate dehydrogenase and causes Beri Beri or Wernicke-Korsakoff Syndrome in alcohol addicts.
Thiamine pyrophosphate is an irreversible step and commits the carbon chain to energy production or lipid synthesis.
How is thiamine pyrophosohate activated and inactivated?
Thiamine pyrophosphate is activated by Ca2+ and inactivated by high ratios of coenzyme A, NADH:NAD, and ATP:ADP.
What are the main outputs of the Krebs cycle?
The main outputs of Krebs are FADH, NADH2, Co2 and GDP.
What enzymes is the Krebs cycle controlled by?
Krebs is controlled by citrate synthase, isocitrate dehydrogenase and alpha ketoglutarate dehydrogenase.
What is oxidative phosphorylation?
It is a 2 coupled process to synthesise ATP.
NADH/FADH are used to create a proton gradient (oxidation).
The energy from the protein gradient is then used to drive phosphorylation (ADP to ATP)
What is the electron transport chain?
A way to generate a proton gradient to generate energy to perfume ATP synthesis
Where does NADH bind on the transport chain and which complexes does it pass through?
NADH binds at complex 1 with a total of 6H+ transported using energy from electrons generating a large protein gradient across the well insulated inner membrane of mitochondria.
NADH passes though complex 1, 3 and 4.
Where does FADH2 bind?
FADH2 binds at complex 2, and causes 4 H+ to be transported.
There is an antiporter in the inner mitochondrial membrane to allow the transport of ATP? What does it do?
ADP is transported into the mitochondria to supply the ATPase, ATP is transported out. Antiporter in inner mitochondrial membrane allows this.
How many protons are required to cross the membrane to synthesise a molecule of ATP?
4 protons must pass into the matrix along with phosphate coursing the inner membrane to produce 1 ATP.
Can NADH produced in the cytosol be reoxidised by electron transport?
No it has to be transported back to the matrix through a series of reactions to be reoxidised.
Where are beta cells in the islets of langerhans found?
The beta cells are mostly central and most abundant. They secrete insulin.
Where are the alpha cells in the islets of langerhans found?
Alpha cells are found at the periphery secreting glucagon.
What does ATP do to the Katp channels during insulin secretion?
ATP closes Katp channels, depolarising the membrane.
What induces the exocytosis of insulin?
Ca2+ influx and CICR induce the exocytosis of insulin.
What does the autonomic nervous system do to insulin secretion?
The PNS drives insulin secretion whilst the sympathetic system inhibits insulin secretion.
What is the significance of C peptide in a clinical situation?
A free C peptide is made during insulin procession in the Golgi. C peptide is a useful marker of endogenous insulin production.
What are the effects of insulin on the liver?
Insulin increases glycogen storage and VLDL production but gluconeogensis and ketone body production are inhibited.
No glut 4 in the liver
What are the effects of insulin in muscle?
Glut4 inserted and favours the use of glucose.
Glycogen, triglyceride and protein synthesis increase.
What does exercise do to the muscle in terms of insulin?
Exercise Via adrenalin induces glut4 and synergises with insulin.
What is the effect of insulin on fat?
Glut 4 inserted and favours uptake of glucose. Triglyceride storage increased and export of free fatty acids and glycerol reduced.
LDL exported to endothelium where it extracts fatty acids from VLDL.
What the effects of glucagon on the liver?
Glucagon receptor is a GPCR linked to Gs.
Glycogen breakdown and gluconeogenesis increase.
Fatty acids used as an energy source and for ketone body production
