Pentose Phosphate Pathway Flashcards
glucose-6-phosphate has 2 fates
1) glycolysis to make ATP
2) pentose phosphate pathway
pentose phosphate pathway
name tells us its products
pentose = 5 carbon sugar (ribose)
phosphate = NADPH
when do we use PPP?
when cells need ribose or NADPH
OR to interconvert sugars
what do we use ribose for
ribose makes nucleotides
what do we use NADPH for
- it is rich in electrons
- useful in various anabolic pathways
- synthesizing fatty acids
- NADPH is an electron donor
- provides reducing power
where does PPP occur?
cytoplasm
requires no Oxygen
all cells can use PPP
PPP 2 phases
1) irreversible oxidative phase yields NADPH
2) reversible non-oxidative phase yields Ribose
oxidation
donates or loses H+ to another molecule
oxidative phase step 1
1) glucose-6-phosphate to 6-phosphogluconate (NADP+ to NADPH)
rate limiting step of oxidative PPP
step 1: glucose-6-phosphate to 6-phosphogluconate
oxidative phase step 2
2) 6-phosphogluconate to ribulose-5-phosphate
- NADP+ to NADPH
- release CO2
oxidative phase products
2 NADPH per 1 glucose
non-oxidative PPP features
flexible and reversible
can generate different products depending on what the cell needs
non-oxidative PPP step 1
1) ribulose-5-phosphate to ribose-5-phosphate
why do we want ribose-5-phosphate?
it can be the 5 carbon sugar for DNA/RNA synthesis
