Glycolysis Flashcards Preview

MCAT biochemistry > Glycolysis > Flashcards

Flashcards in Glycolysis Deck (24):
1

the net products are

2 ATP
2 NADH
2 pyruvate

2

the two phases are

investment phase (input of 2 ATP)
payoff phase (net products are produced)

3

oxidoreductases

catalyze oxidation-reduction (redox) reactions

4

transferases

catalyze transfer of functional groups from one molecule to another

5

hydrolases

catalyze hydrolytic cleavage

6

lyases

catalyze removal/addition of a group from/to a double bond or other cleavages involving electron arrangements

7

isomerases

catalyze intramolecular rearrangement

8

mutases

shifting of functional groups from one position to another in the same molecule

9

ligase

catalyze reaction in which two molecules are joined

10

kinases

catalyze reaction involving transfer of phosphoryl group

11

overview of glycolysis is to reduce/oxidize what to what?

glucose is oxidized to pyruvate and NAD+ is reduced to NADH

12

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

13

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)

14

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

15

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

16

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

17

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

18

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)

19

reaction 8: phosphoglycerate mutase

it is the rearrangement of
3-phosphoglycerate (3PG) to 2-phosphoglycerate (2PG) using the phosphoglycerate mutase enzyme

20

reaction 9: enolase

the enolase enzyme removes a molecule of water from 2-phosphoglycerate to form phosphoenolpyruvate (PEP) and water

21

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

22

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+

23

takes place in what part of the cell?

cytoplasm

24

do this process require oxygen?

no