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12 Cards in this Set
- Front
- Back
- 3rd side (hint)
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GLUT 2
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-in intestinal mucosal cells toward enterohepatic circulation, liver, kidney and β-pancreatic cells
-large Kt for glucose -low affinity transporter -very efficient at high glucose concentrations |
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GLUT 5
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-intestinal mucosal cells towards lumen, testes
-transports fructose mostly; glucose at high concentration |
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GLUT 4
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-fat cells, muscle
-stored inside cell -insulin mobilizes transport to plasma membrane during glucose influx -high affinity glucose transporter -pts with DM can't use GLUT4 efficiently |
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GLUT 1
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-RBC
-glucose uptake at essential constant rate at normal blood glucose concentration -high affinity transporter |
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GLUT 3
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-RBC
-neurons -glucose uptake at essential constant rate at normal blood glucose concentration -high affinity transporter |
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Stage 1: Energy Investment Phase
(from glucose) |
Glucose + ATP > Glucose 6 Phosphate + ADP
-glucokinase or hexokinase *uses 1 ATP *REGULATORY STEP- energy investment phase, irreversible |
-glucokinase- Liver only, has high Km- more active when blood glucose elevated
-traps G6P in liver cell -mutation in rare inherited form of DM doesn't allow Phos >hyperglycemia -hexokinase- all other tissues, low Km- can metabolize glucose at all concentrations |
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Glucose 6 Phosphate fates
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-fate depends on fed/fast state, insulin/glycogon levels
-pyruvate/glycolysis -storage in glycogen -HMP shunt/pentose phosphate pathway |
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Stage 1: Energy Investment Phase cont'd
(from Glucose-6-Phosphate) |
-G6P > fructose 6 phosphate via phosphoglucose isomerase
-F6P + ATP > Fructose 1,6 Bisphos via PFK1 *PFK1 most important regulatory step *irreversible reaction |
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Stage 2: Cleavage of 6C sugar
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F6P > Glyceraledhyde 3-phosphate + dihydroxyacetone phosphate
via Aldolase A |
dihydroxyacetone phosphate > glyceraldehyde 3 phosphate
-via triosephosphate isomerase |
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Stage 3: Energy Generation Phase
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Glyceraldehyde 3 Phosphate + NAD+ > 1,3 Bisphosphoglycerate + NADH + H+
-via G3P dehydrogenase *NADH produced (~3 ATP) |
1,3 BPG > 3 phosphoglycerate + ATP
- via phosphoglycerate kinase *1,3 BPG high energy intermediate forms ATP!! 3 phosphoglycerate > 2 phosphoglycerate - via phosphoglycerate mutase |
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Stage 3: Energy Generation Phase cont'd (pyruvate formation)
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2 phosphoglycerate > phosphoenol pyruvate
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phosphoenol pyruvate + ADP > pyruvate + ATP
*phosphoenol py is high energy compound *3rd IRREVERSIBLE reaction |
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Lactic Acid Formation
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Pyruvate + NADH + H+ > Lactate + NAD+
-via lactate dehyrdogenase (LDH) - cytosolic -NADH formed by glyceraldehyde 6 phoshphate dehydrogenase is reoxidized to form NAD+ --> glycolysis can proceed in absence of mitochondria -direction of rxn depends on NADH/NAD+ ratio |
-anaerobic environment
+absence of mitochondria +poorly vascularized- RBC, lens, cornea, leucocytes +lack of oxygen- contracting white skeletal muscle cells |
