glycolysis

anaerobic organisms

organisms that don't use o2 also have this pathway

energy payoff phase overview

-each 3 carbon sugar (G3P) is converted into another 3 carbon molecule (PYRUVATE) through series of reaction -atp and 1 nadh is produced (phase occurs twice so 4 tap and 2 nadh are produced

where does glycolysis take place?

-in cytosol of cell -can be broken down into 2 stages: energy investment and energy payout phase

enzyme phosphofructokinase

-most important for regulation of glycolysis -each reaction in glycolysis is catalyzed by its own enzyme -catalyzes the formation of unstable 2 phosphate 6 carbon molecule (fructose, 6 biphosphate) -speeds up/slows down glycolysis in response to energy needs of the cell

energy investment phase overview

-starting molecule of glucose gets rearranged and 2 phosphate groups are attached to it -phosphate groups make modified sugar unstable and allow it to split in half and form 2 phosphate bearing 3 carbons -2 atps are "invested" in this phase`

DETAILED energy investment phase

1. phosphate transferred from atop to glucose and makes glucose 6-phosphate 2. glucose 6 phosphate is contorted into isomer, fructose 6 phosphate 3. 1 phosphate group is transferred from atp to fructose-1, 6 biphosphate --step is catalyzed by phosphofructokinase

cells use 2 mechanisms to generate nad+

1. when o2 is present: nadh can pass electrons into etc and regernate nad+ for glycolysis. produces atp too 2. when o2 is absent: cells use other simpler pathways to make nad+. nadh donates its electrons to an acceptor molecule that doesn't make atp but does generate nad+

end products of glycolysis

2 atp, 2 nadh, 2 pyruvate

DETAILED EI part 2

4. fructose-1, 6 biphosphate splits into 2, 3-carbon sugars: DHAP and G3P --are isomers of each other but only g3p can continue 5) dhap is converted into g3p. all exist in equilibrium and all dhap is eventually converted into g3p

DETAILED ENERGY PAYOFF PHASE

6. g3p loses 2 electrons and 2 protons, reducing nad+ to nadh. this reaction releases energy which is used to attach another phosphate to the sugar and makes 1, 3 biphosphogylerate 7. 1, 3 biphosphoglycerate donates 1 of its phosphate groups to adp and makes atp; becomes 3 phospho....

DETAILED EP part 2

8. 3 phosphoglycerate is converted into isomer 2 phosphoglyerate 9. 2 phosphoglycerae loses 1 h2o and become PEP -pep is unstable and will lose its phosphate group at the end 10. pep donates phosphate group to adp and makes a 2nd molecule of atp PEP BECOMES PYRUVATE END PRODUCT

pyruvate in glycolysis

can be oxidized (broken down) into co2 and make lots of atp

nad+ in glycolysis

is used to accept electrons and if there's no nad+ then the reaction CANNOT take place -if glycolysis ran in isolation for a while, it would eventually come to a stop because all nad+ would be used up

glycolysis

series of reactions that extract energy from glucose by splitting it into 2 three carbon molecules called PYRUVATE -first step of CR

energy investment phase part 2

the 3 carbon sugars that formed (g3p and dhap) when unstable sugars were break down are different from each other; only one (G3P) can go to the next step

dhap

will be converted into g3p