Glucose Metabolism Flashcards
Reactant in step 1
Glucose
Product in step 1
Glucose-6-phosphate
Reactant in step 2
Glucose-6-phosphate
Product in step 2
Fructose-6-phosphate
Reactant in step 3
Fructose-6-phosphate
Product in step 3
Fructose-1,6-bisphosphate
Reactant in step 4
Fructose-1,6-bisphosphate
Product in step 4
Glyceraldehyde-3-phosphate and dihydroxyacetone phosphate
Reactant in step 5
Dihydroxyacetone phosphate
Product in step 5
Glyceraldehyde-3-phosphate
Reactant in step 6
Glyceraldehyde-3-phosphate
Product in step 6
1,3-bisphosphoglycerate and NADH
Reactant in step 7
1,3-bisphosphoglycerate and H2O
Product in step 7
3-phosphoglycerate and phosphate
Reactant in step 8
3-phosphoglycerate
Product in step 8
2-phosphoglycerate
Reactant in step 9
2-phosphoglycerate
Product in step 9
Phosphoenolpyruvate
Reactant in step 10
Phosphoenolpyruvate and H2O
Product in step 10
Pyruvate and phosphate
Enzyme in step 1
Hexokinase
Enzyme in step 2
Phosphohexose isomerase
Enzyme in step 3
Phosphofructokinase
Enzyme in step 4
Fructose-1,6-bisphosphate aldolase
Enzyme in step 5
Triose-phosphate-isomerase
Enzyme in step 6
G-3-P dehydrogenase
Enzyme in step 7
P-glycerate kinase
Enzyme in step 8
P-glycerate mutase
Enzyme in step 9
Enolase
Enzyme in step 10
Pyruvate kinase
Coenzyme in step 6
Phosphate and NAD+ -> NADH and H+
Coenzyme in step 7
ADP -> ATP
Coenzyme in step 8
None
Coenzyme in step 9
H2O released
Coenzyme in step 10
ADP and H+ -> ATP
Coenzyme in step 1
ATP -> ADP
Coenzyme in step 2
None
Coenzyme in step 3
ATP -> ADP
Coenzyme in step 4
None
Coenzyme in step 5
None
What are the 2 phases of glycolysis and what occurs in each phase?
1) Preparatory - glucose if phosphorylated and split into 2 triose phosphates; costs 2 ATP
2) Payoff - oxidation and phosphorylation yield 2 NADH and 4 ATP
Is glucose metabolism an exergonic or endergonic pathway?
Exergonic
Is step 1 exergonic or endergonic?
Endergonic
How is glucose-6-P isomerized to fructose-6-P in step 2?
Via aldose/ketose isomerization
Is step 3 exergonic or endergonic?
Endergonic
Which steps in the preparatory phase cost 2 ATP?
Steps 1 and 3
What are some characteristics of phosphofructokinase?
- Activated by AMP
- Inhibited by ATP at allosteric binding sites
What is the function of adenylate kinase?
“Squeeze” some ATP out of ADP through the reaction 2 ADP -> ATP and AMP
What is important to remember about step 5?
There are now 2 G-3-P molecules formed, so from now on there are 2 reactants and 2 products for each following step
What type of reaction is step 6?
Oxidation and phosphorylation
What is important about step 7?
1 ATP is produced per 3-C compound, so 2 ATPs are produced per glucose
Is step 7 exergonic or endergonic?
Exergonic
Where do glycolysis occur?
In the cytoplasm
The enzymes of glycolysis are ____-soluble
Water
What type of reaction occurs in step 8?
A rearrangement with an intramolecular transfer of the phosphate group
Define mutase
An enzyme that transfers a functional group from one part of a molecule to another
What type of reaction is step 9?
Dehydration
What type of reaction is step 10?
Substrate level phosphorylation
Why is step 10 called a regulation step?
Pyruvate kinase is allosterically inhibited by ATP, acetyl-CoA, and fatty acids
What happens to pyruvate in yeast?
It becomes ethanol and CO2
What happens to pyruvate in animals and plants?
It becomes acetyl-CoA and CO2, and is then converted into 2 CO2 and 2 H2O
What happens to pyruvate in muscles and microbes?
It becomes lactate
What enzyme converts pyruvate to lactate?
Lactate dehydrogenase
What is the coenzyme of lactic acid fermentation?
NADH -> NAD+
What enzyme converts pyruvate into ethanol?
Pyruvate decarboxylase
What enzyme converts ethanol to acetaldehyde?
Alcohol dehydrogenase
What enzyme converts pyruvate to acetyl-CoA?
Pyruvate dehydrogenase complex (E1, E2, and E3)
What are the coenzymes involved in converting pyruvate to acetyl-CoA?
- CoA-SH in
- NAD+ -> NADH
- TPP, lipoate, and FAD
