Glycolysis Flashcards
the net products are
2 ATP
2 NADH
2 pyruvate
the two phases are
investment phase (input of 2 ATP) payoff phase (net products are produced)
oxidoreductases
catalyze oxidation-reduction (redox) reactions
transferases
catalyze transfer of functional groups from one molecule to another
hydrolases
catalyze hydrolytic cleavage
lyases
catalyze removal/addition of a group from/to a double bond or other cleavages involving electron arrangements
isomerases
catalyze intramolecular rearrangement
mutases
shifting of functional groups from one position to another in the same molecule
ligase
catalyze reaction in which two molecules are joined
kinases
catalyze reaction involving transfer of phosphoryl group
overview of glycolysis is to reduce/oxidize what to what?
glucose is oxidized to pyruvate and NAD+ is reduced to NADH
reaction 1: hexokinase
it is the conversion of D-glucose to glucose-6-phosphate
hexokinase enzyme assists in phosphorylaion by transfering the phosphorous group from Mg2+ATP to the D-glucose to product G6P
ADP is also a product
reaction 2: glucose-6-phosphate isomerase
it is the conversion of G6P to fructose-6-phosphate (F6P) by catalyzing the intramolecular arrangement
G6 isomerase enzyme assists in isomerization by converting the six-membered ring into a five-membered ring (so that carbon 1 is now on the outside of the ring)
reaction 3: phosphofructokinase
it is the conversion of F6P to fructose-1,6-biphosphate (FBP) by a transfer of a phosphote group
phosphofructokinase enzyme assists in the phosphorylation by transfering another phosphorous group from Mg2+ATP to the product FBP
ADP is also a product
reaction 4: aldolase
it is the split of FBP into two sugars that are isomers of one another - dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GAP)
aldolase enzyme assists by catalyzing the cleavage of FBP to yield the two molecules
reaction 5: triose phosphate isomerase (TPI)
it is the rearrangement of dihydroxyacetone phosphate (DHAP) to GAP so it can be used in the rest of glycolysis (GAP from reaction 4 continues to reaction 6)
TPI assists by rapidly catalyzing the intramolecular bonds for rearrangement
reaction 6: glyceraldehyde-3-phosphate dehydrogenase (GAPDH)
it is the conversion of GAP to 1,3-biphosphoglycerate (BPG)
the first step is that GAP is oxidized by NAD+ thus the second step is phosphorylated by the addition of a free phosphate group to make BPG, the reaction catalyzed by GAPDH enzyme
NADH is also a product
reaction 7: phosphoglycerate kinase (PGK)
it is the conversion of BPG to 3-phosphoglyercate (3PG) by PGK enzyme
BPG losses a phosphate group to begin and it is transfered to an ADP molecule to become ATP thus 3PG is formed
*this is the first production site of ATP (two molecules are being synthesizes throughout thus the net production of ATP is at 0 now)
reaction 8: phosphoglycerate mutase
it is the rearrangement of
3-phosphoglycerate (3PG) to 2-phosphoglycerate (2PG) using the phosphoglycerate mutase enzyme
reaction 9: enolase
the enolase enzyme removes a molecule of water from 2-phosphoglycerate to form phosphoenolpyruvate (PEP) and water
reaction 10: pyruvate kinase
it is the transfer of the phosphate group of PEP to ADP to form pyruvate and ATP (2 molecules) using the pyruvate kinase enzyme
what happens afterwards?
under aerobic conditions (presence of oxygen) the pyruvate produced enters the pyruvate dehydrogenase complex to be converted to acetyl-CoA then to the Krebs cycle
under anaerobic conditions (absence of oxygen) the pyruvate produced enters fermentation to be used for the regeneration of NAD+
takes place in what part of the cell?
cytoplasm
do this process require oxygen?
no
