Biochem Final Glycolysis Flashcards
each process in cellular respiration produces either
overview cellular respiration
ATP or electron carries (3 NADH and 2 FADH2)
Glycolysis: 1 6-carbon glucose broken into 2 pyruvate
Pyruvate processing: each pyruvate oxidized to form acetyl coA
Citric Acid Cycle: each acetyl coA is oxidized to form CO2
ETC and oxidative phosphorylation: electrons move down ETC and their energy is used to create proton gradient which is used to make ATP (32 ATP in the end)
definition of cellular respiration
any set of reactions that use electrons from high energy molecules to make ATP
where other macromolecules can enter cellular respiration in the absence of glucose
glycolysis: sugars or glycerol
pyruvate oxidation: amino acids converted to pyruvate
citric acid cycle: fatty acids and amino acids can be converted to acetyl coA
or amino acids can directly enter citric acid cycle
in a basic sense how does fermentation and anaerobic respiration work?
electronegative molecules function kind of as the oxygen molecule electron acceptor in a more simplified anaerobic pathway
4 major pathways of glucose utilization
synthesis of structural polymers - extracellular matrix and cell walls
storage synthesis - glycogen, starch, sucrose
ribose 5-phosphate - oxidation via pentose phosphate pathway
pyruvate - oxidation via glycolysis
importance of the study of glycolysis for biochemistry
understanding roles of coenzymes (study of cancer), discovery of pivotal role of ATP, enzyme purification methods, inspo for next gen
preparatory phase
requires 2 ATP
enzymes: hexokinase, phosphohexose isomerase, phospho-fructokinase 1, aldolase
produces 1 GAP and 1 DHAP
importance of phosphorylating glucose as first step of glycolysis
so that glucose cannot leave cell
reduce concentrations of glucose in cell so that more comes
2 priming reactions in preparatory phase
phosphorylation of glucose by hexokinase to glucose 6-phosphate (step 1)
and phosphorylation of fructose-6-phosphate to fructose 1,6-bisphosphate (step 3)
glycolysis phosphorylation of glucose
step 1: C6 nucleophilic oxygen attacks phosphate of ATP
1 ATP consumed producing glucose-6-phosphate
thermodynamically favorable/irreversible
catalyzed by hexokinase and Mg2+
regulated by substrate inhibition
glycolysis phosphohexose isomerization
step 2: conversion of glucose 6-phosphate to fructose 6-phosphate (aldose to ketose)
catalyzed by phosphohexose isomerase and Mg2+
slightly unfavorable/reversible
easier to phosphorylation and symmetrical molecule
glycolysis phosphorylation of fructose 6-phosphate
step 3: phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate
catalyzed by PFK-1 and Mg2+, 1 ATP consumed
thermodynamically favorable/irreversible
highly regulated by availability of ATP (high ATP, no reaction)
glycolysis cleavage of fructose 1,6-bisphosphate
Step 4: fructose 1,6-bP cut in half to the right of O and C3/C4 creating glyceraldehyde 3-phosphate (GAP) (aldose) and dihydroxyacetone phosphate (ketose)
catalyzed by aldose
end of preparatory phase
thermodynamically unfavorable, reversible
product concentration kept low to pull rxn forward
glycolysis triose phosphate interconversion
Step 5: first step of payoff phase
conversion of dihydroxyacetone phosphate (DHAP) into a 2nd GAP molecule
only GAP is substrate for next step in pathway
catalyzed by triose phosphate isomerase
thermodynamically unfavorable/reversible
product concentration kept low to pull rxn forward
glycolysis GAP dehydrogenase
Step 6: oxidation of GAP to 1,3-bisphosphoglycerate
1 NADH produced (energy yielding step)
catalyzed by glyceraldehyde 3-phosphate dehydrogenase
thermodynamically unfavorable, reversible
coupled to step 7 to pull it forward
glycolysis 1st production of ATP
Step 7: phosphate transfer from 1,3-bisphosphoglycerate to 3-phosphoglycerate + 1 ATP
catalyzed by phosphoglycerate kinase and Mg2+
thermodynamically favorable/irreversible
ex. of substrate level phosphorylation
glycolysis migration of phosphate
Step 8: 3-phosphoglycerate phosphoryl group moves from C2 to C3 to make 2-phosphoglycerate
catalyzed by phosphoglycerate mutase and Mg2+
thermodynamically unfavorable, reactant concentration kept high
reactant concentration kept high to push rxn foward
mutases
catalyze migration of functional groups
glycolysis dehydration from 2-phosphoglycerate
Step 9: 2-phosphoglycerate dehydrated to phosphoenolpyruvate (better phosphate donor)
catalyzed by enolase
thermodynamically unfavorable/reversible
dehydration, water released
product concentration kept low to pull reaction forward
glycolysis 2nd production of ATP
Step 10: phosphoenolpyruvate gives phosphoryl group to form 1 ATP and pyruvate
tautomerization occurs afterwards, decreasing product concentration
catalyzed by pyruvate kinase and Mg2+, Mn2+, K+
highly thermodynamically favorable, irreversible
regulated by ATP, divalent metals
types of phosphorylation compared
substrate level - ATP produced by enzyme catalyzed transfer of phosphate group to ADP from intermediate
oxidative phosphorylation - proton gradient provides energy for membrane protein ATP synthase to phosphorylate ADP
glycolysis regulation
high ATP binds to regulatory binding site on step 3 enzyme phosphofructokinase
total products made from glycolysis
2 pyruvate, 4 ATP (2 net), 2 NADH
irreversible steps of glycolysis
Step 1: C6 nucleophilic oxygen attacks phosphate of ATP producing glucose-6-phosphate, 1 ATP consumed
Step 3: phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate
Step 10: phosphoenolpyruvate gives phosphoryl group to form 1 ATP and pyruvate
which steps have covalently bound enzyme intermediates?
Aldolase and glyceraldehyde-3-phosphate dehydrogenase
high energy intermediates in glycolysis
1,3-bisphosphoglycerate and phosphoenolpyruvate (precursors to steps 7 and 10 production of ATP from ADP)
which glycolysis reactions is Mg2+ present?
Steps 1-3, 7, 8 and 10
when is dehydration reaction in glycolysis?
step 9: 2-phosphoglycerate to phosphoenolpyruvate
thermodynamically favorable steps
all involving ATP production or use
Steps 1, 3, 7 and 10
