Lecture Set 17 Flashcards
How does gluconeogenesis work if some steps of glycolysis are irreversible?
Not the exact same pathways, have enzymes to bypass the specifically irreversible steps
Use glucose-6-phosphatase instead of hexose kinase
Use Fructose-1,6-bisphosphatase instead of phosphofructose kinase-1
Use pyruvate carboxylase to form oxaloacetate, then phosphoenolpyruvate carboxykinase to get to phosphoenolpyruvate instead of pyruvate kinase
How does AMP, ATP, G6P, acetyl-CoA, fructose-2,6-bisphosphate regulate gluconeogenesis
AMP activates glycolysis (phosphofructokinase-1) and inhibits gluconeogenesis (fructose-1,6-bisphosphatase), ATP inhibits glycolysis (phosphofructokinase-1), G6P inhibits glycolysis (hexokinase), acetyl-CoA inhibits glycolysis (pyruvate kinase) and activates gluconeogenesis (pyruvate carboxylase), fructose-2,6-bisphosphate inhibits gluconeogenesis (fructose-1,6-bisphosphotase)
AMP and ATP bind to the allosteric sites on PFK1
f-2,6-P increases affinity of pfk1 for f-6-phosphate
where is acetyl-CoA formed, how is it formed?
formed in the matrix of the mitochondria, formed by pyruvate dehyrogenase
why is there no net synthesis of glucose from acetyl CoA?
Uses 2 carbons from acetyl group to form with oxaloacetate to form citrate, loses 2 carbons as CO2, therefore no net synthesis
How is the citric acid cycle regulated by NADH and ADP?
NADH inhibits, ADP activates the citric acid cycle
NADH = need to slow down to allow ETC to catch up
ADP because you need to produce more ATP
Describe the structure of the mitochondria
Has the outer membrane, then an inner membrane, with intermembrane space in between. The membrane form folds (cristae) and inside there is the matrix
Why is more ATP produced by a triacylglyceride than a glucose molecule?
glucose only produces 2 ATP, while triacylglyceride, can break down the fatty acid 2 carbons at a time to produce acetyl-CoA
What is the difference between electron transport and oxidative phosphorylation?
electron transport = reducing equivalents (NADH and FADH2 re-oxidized, through transfer of electrons down series of electron transport proteins in the inner membrane)
oxidative phosphorylation = process of ATP formation by transfer of electrons from NADH or FADH2 to O2
How does ATPsynthase produce ATP
Energy produced from transfer of electrons down ETC used to pump protons out, create an electrochemical gradient. Flows back in through ATPsynthase, and ATP synthesized.
ATP synthase has F0 and F1. F0 is in the membrane, made of a1b2c9-12. F1 is outside the membrane, has three αβ subunits and one γ,
How is respiration regulated?
controlled through substrate availability (ADP, Pi, O2, NADH/FADH2) ADP stimulates ATP synthesis and respiration
What are the metabolic fates of acetyl-CoA
cannot enter into gluconeogenesis, committed to citric acid cycle, so it can either be oxidated to CO2 or used in lipid (fatty acid) synthesis
Why does the citric acid cycle need oxygen?
FAD and NAD+ are electron carriers, can only be regenerated if there is transfer of electrons to oxygen through ETC
