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29 Cards in this Set
- Front
- Back
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What the official name for glycolysis?
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Embden-Meyerhof-Parnas Pathway
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What is produced from one molecule of glucose?
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2 ATP
2 Pyruvate 2 NADH |
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What is the end product of glycolysis if it can't continue on to aerobic pathways (no mitochondria)?
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Lactate
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What happens to pyruvate in the mitochondria?
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oxidized into acetyl CoA and then enters TCA/Krebs/citric acid pathway
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What are the 6 classes of enzymes in glycolysis and what they do?
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-Kinase - adds P to glucose
-Mutase - shifts fxnl groups from one spot to another on same molecule -Dehydrogenase - oxidizes by reduction (NADH/FADH side product) -Cleaving Enzyme - cuts chains/rings up -Isomerase - rearranges to alternate structural form -Enolase - breaking of various chemical bonds by means other than hydrolysis and oxidation |
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What are the 2 stages of Glycolysis?
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-Energy investment - rxns 1-5, prep stage, consumes 2 ATP
-Energy recovery - rxns 6-10, generates 4ATP, 2 pyruvate |
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What is the overall rxn of glycolysis?
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glucose + 2NAD* + 2ADP + 2Pi --> 2 pyruvate + 2NADH +2ATP + 2 H2O + 4H*
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What are the 2 molecules and enzyme of rxn 1 and is it reversible?
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glucose + hexokinase + ATP + Mg++ --> Glucose-6-phosphate (G6P)
--glucokinase in the liver --not reversible |
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Why is glucose phosphorylated in rxn 1 and what purpose does the Mg++ serve?
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-the neg charge from P keeps glucose from leaving the cell
-Mg++ shields the neg ATP charge and allows it to get close to glucose - nucleophilic attack |
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Is hexokinase specific to glucose?
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Nope, it can get others like mannose, fructose
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Glucose-6-phosphate is a metabolic junction. What are the 3 directions the molecule can go from here?
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-continue glycolysis
-storage as glycogen -Pentose phosphatase shunt |
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Where is glucokinase used?
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hepatocytes and islet (pancreatic) cells
-not inhibited by glucose-6-phosphate like hexokinase -different functions in liver and pancrease |
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How does the liver respond in hyperglycemic and hypoglycemic periods?
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hyper - hepatocyte glucose uptake is increased due to increased levels of glucokinase
---hepatocyte glucokinase initiates the metabolism of glucose hypo - hepatocyte glucokinase levels are reduced and the liver becomes a provider of glucose |
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What does glucokinase do in Beta cells of the pancreas?
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sense and modulate insulin secretion
increase glucose uptake --> increase glucokinase expression and use --> decrease in ATP --> blockage of ATP sensitive K+ channel --> Insulin secretion |
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What are the molecules and the enzyme in rxn 2 and is it reversible?
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glucose-6-phosphate + phosphoglucose isomerase <--> Fructose-6-phosphate
reversible |
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What are the molecules and the enzyme in rxn 3 and is it reversible?
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Fructose-6-phophate + ATP + phophofructokinase --> Fructose-1,6-bisphospate
not reversible - a rate limiting step |
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What are the molecules of rxn 4, the enzyme, and is it reversible?
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Fructose-1,6-bisphosphate + aldolase <--> Dihydroxyacetone phosphate + Glyceraldehyde-3-phosphate
reversible |
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What happens in rxn 5, the enzyme used, and is it reversible?
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dihydroxyacetone phosphate <--> Enediol intermediate <--> Glyceraldehyde-3-phosphate
Triose phosphate isomerase only GAP continues - reversible |
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What are the molecules of rxn 6, the enzyme, and is it reversible?
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Glyceraldehyde-3-phosphate + NAD* + Pi + glyceraldehyde-3-phosphate dehydrogenase <--> 1,3-Bisphosphoglycerate + NADH + H*
reversible |
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What are the molecules of rxn 7, the enzyme, and is it reversible?
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1,3-bisphosphoglycerate + ADP + phosphoglycerate kinase <--> 3-phosphoglycerate + ATP
reversible finally make 2 ATP |
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What are the molecules of rxn 8, the enzyme, and is it reversible?
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3-phosphoglycerate + phophoglycerate mutase <--> 2-phosphoglycerate
reversible |
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What are the molecules of rxn 9, the enzyme, and is it reversible?
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2-phosphoglycerate + enolase <--> phosphoenolpyruvate + H2O
reversible |
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What are the molecules of rxn 10, the enzyme, and is it reversible?
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phosphoenolpyruvate + ADP + H* + pyruvate kinase --> pyruvate + ATP
not reversible, make 2 more ATP |
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What are the 3 fates of pyruvate?
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aerobic - oxidative phosphorylation: pyruvate --> Acetyl CoA and enters Krebs --> CO2 + H2O
anaerobic - homolactic fermentation: Pyruvate + NADH + lactate dehydrogenase <--> Lactate + NAD* alcoholic fermentation: Pyruvate + NADH --> Ethanol + NAD* + CO2 |
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At what rxns do galactose, mannose, and fructose enters glycolysis?
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-galactose - 2nd rxn
-mannose - 3rd rxn -fructose (muscle) - rxn 3 fructose (liver) - rxn 5 |
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What are the 3 enzymes that regulate glycolysis?
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-hexokinase - rxn 1
-phosphofructokinase - rxn 3 -pyruvate kinase - rxn 10 |
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What are the 3 fxns of the Pentose Phosphate Pathway (PPP)?
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-generation of pentose - used for synthesis of nucleic acids and nucleotides
-production of fatty acids - membrane synthesis, RBC structure, etc -cell detoxification by removal of destructive forms of oxygen |
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What is generated by the oxidation of glucose-6-phophate via the PPP?
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NADPH + R5P (can enter back into glycolisis if no nucleotides are needed)
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In what tissues is PPP usually done?
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where lipid biosynthesis is taking place
--liver, mammary gland, adipose tissue, adrenal cortex -30% of glucose oxidation in liver occurs in PPP and not glycolysis |
