PPP and why do we need it

Question 1

Why do we need it?

Answer 1

ATP is primary E currency, but so is reducing power… endergonic reactions may require NADPH. Not metabolically interchangable, enzymes are specific.

NADPH uses ∆Goxi of metabolites for reductive biosynthesis (producing fats)

Question 2

Other functions of PPP

Answer 2

nucleotide biosynthesis, R5P to another sugar, which is converted to a scaffold to produce purine/pyrimidine base.

If only need NADPH then we will have a ratio of 1 R5P : 2 Xu5P (u = ketose)four

Question 3

four stages

Answer 3

reversible : 2,3,4… non reversibel stage is stage 1….
We have modes bc cells are dependent on different things. (reversible)

stage 1: oxidative stage (nonreversible) produces NADPH x6….

stage 2: Isomerization and epimerization … 3Ru5P (ketose sugar) > R5P + 2Xu5P (epimerization)

stage 3: C bond breaking and forming

stage 4: recycling back to stage 1

Question 4

Xu5P regulates

Answer 4

flux controller of liver. Because this is occurring a lot in the liver.. as Xu5P concentration increases in PPP, glycolysis rates will increase.
Why are these coupled?
If a lot of extra glucose, Xu5P that is involved in the process of making of NADPH, and extra acetyl-coA will make fat. (Huh??????)

Question 5

the three modes of PPP

Answer 5

First one is nucleotide synthesis… when the primary need is for nucleotide biosynthesis, the primary product is R5P

Second is NADPH synthesis, has to have GNG involved, bc want to take F6P and cnvert to G6P… largely using PPP and piece of GNg to make a lot of NADPH for doing fat synthesis or some other type of reductive biosynthesis.n

third is energy generation, takimg G6P making Ru5P , continuigng throguh PPP but also glycolysis.