Glycolysis Flashcards
(24 cards)
3 Stages of Catabolism
Stage I: Hydrolysis of complex molecules to component building blocks (carbs-monosaccs, prots-AAs, etc)
Stage II: Conversion of building blocks to acetyl-CoA (or other simple intermediates)
Stage III: Oxidation of acetyl CoA/oxidative phosphorylation
Regulation of Glycolysis
cAMP pathway from GPCR
Na+-Independent Glucose Import
Vesicles w/ GLUT merge with membrane, glucose binds, causes outside to close and inside to open so it passes through with concentration gradient
2 Phases of Glycolysis
Energy Investment Phase (1st 5 Steps)
Energy Generation Phase (2nd 5 steps)
1st Step of Glycolysis
Gluco/hexokinase immediately converts D-Glucose to Glucose-6-PO4
1st energy investment of ATP
1st irreversible/regulatory step
Difference b/w Hexo/Glucokinase (3)
Glucokinase in liver, hexo everywhere else
Gluco deals w/ onslaught of glucose so low affinity (high Km) but high Vmax
Hexokinase needs constant, steady work so high affinity (low Km) but low Vmax
Glucokinase Regulation (3)
Glucokinase regulatory protein (GKRP) sequesters it until glucose activates release, then fructose-6-phosphate activates sequestration again
2nd Step of Glycolysis
Phosphoglucose isomerase converts G6P to F6P (aldose to ketose)
3rd Step of Glycolysis
Phosphofructokinase-1 converts F6P to Fructose 1,6-bisphosphate
2nd investment of ATP
2nd irresversible/regulatory step
2 Inhibitors and 2 Activators of PFK-1
I: ATP, citrate
A: AMP, F-2,6-bisPO4
4th Step of Glycolysis
Aldolase cleaves fructose 1,6-bisPO4 to glyceraldehyde 3-phosphate and dihydroxyacetone PO4
Triose Phosphate Isomerase (5th Step)
Isomerizes aldose and ketose, converts b/w glyceraldehyde 3-PO4 and dihydroxyacetone PO4
PFK-1 Regulation (4)
High insulin/glucagon ratio causes decreased cAMP and reduced active PKA
Decreased PKA favors dephospho of PFK-2/FBP-2
Dephosphorylated PFK-2 is active and FBP-2 inactive, favoring formation of fructose 2,6-bisPO4
Elevated Fructose 2,6-bisPO4 causes activation of PFK-1, leading to increased glycolysis
6th Step of Glycolysis
Glyceraldehyde 3-PO4 Dehydrogenase converts glyceraldehyde 3-PO4 to 1,3-bisphosphoglycerate using inorganic Pi (doesn’t count as energy investment)
First energy generation step, produces NADH + H+
7th Step of Glycolysis
Phosphoglycerate kinase converts 1,3-bisphosphoglycerate to 3-phosphoglycerate
2nd energy generation step, produces ATP
Mutase
Changes 1,3-bisphosphoglycerate to 2,3-bisphosphoglycerate then phosphatase converts to 3-phosphoglycerate
8th Step of Glycolysis
Phosphoglycerate mutase converts 3-phosphoglycerate to 2-phosphoglycerate
9th Step of Glycolysis
Enolase converts 2-phosphoglycerate to phosphoenolpyruvate (PEP) w/ release of H2O
10th Step of Glycolysis
Pyruvate kinase converts PEP to pyruvate
3rd energy releasing step, creates ATP (2nd one to do that)
3rd irreversible step, regulatory
Regulation of Pyruvate Kinase (2)
Fructose 1,6-bisphosphate activates, earlier in the chain so kinda warns pyruvate kinase that substrates are coming
Glucagon inhibits by activating adenylyl cyclase-cAMP to activate PKA, which phosphos pyruvate kinase to inactivate it
Hemolytic Anemia
From mutant deficiency of 1. G6P dehydrogenase or 2. Pyruvate kinase
Huge problem for RBCs because no mt so they get all their ATP from glycolysis/anaerobic respiration
Anaerobic Respiration
Lactate dehydrogenase converts pyruvate to lactate, consuming NADH + H+
3 Irreversible/Regulatory Steps of Glycolysis
Gluco/hexokinase
Phosphofructokinase (main)
Pyruvate kinase
Ethanol Synthesis
From TPP converting pyruvate to acetaldehyde and then EtOH in yeast
