Lecture 19 Flashcards
What is the Pentose Phosphate Pathway ?
– primarily an anabolic pathway, but it involves the catabolism of glucose and occurs in cytosol
T or F, PPP converts glucose to NADPH and ribose 5-phosphate
True
T or F, NADPH used as reducing power for biosynthesis
True
T or F, ribose-5-phosphate and its derivatives are the building blocks for synthesis of RNA, DNA, ATP, NADH, and other important molecules
True
What are the two ways plants make NADH?
– PPP
– photosynthesis
– organisms w/o photosynthesis use only PPP
What is the net product of NADPH CO2 and F6P and GAP from 3 molecules of glucose?
6 NADPH
2F6P
1 GAP
3 CO2
What is the main enzyme involved in the oxidative phase of PPP?
glucose 6 phosphate dehydrogenase
phosphogluconate dehydrogenase
What conditions favor product of NADPH?
- fatty acid synthesis
- oxidative stress
- synthesis of XNA, ATP, and NADH
Which enzyme in the oxidative portion of PPP is responsible for decarboxylation?
6- phosphogluconate dehydrogenase
What is the starting product and ending product of the oxidative portion of PPP
- Glucose 6 phosphate –> NADP+ is reduced to NADPH in the process
- ribulose-5-phosphate
True or false
PPP pathway can continue with only 1 glucose for only stage 1
trye
Which enzyme is responsible for the conversion of ribulose to ribose in PPP pathway?
phosphopentose isomerase
Which enzymes are used in the non-oxidative stage of PPP
- transketolase
- - transaldolase
What is the stoichiometric representation of reactants needed to create the typical amount of products of the last stage of PPP?
3C5 —> 2C6 + C3
Which of the following is the correct order of enzyme activity in the second stage of PPP?
A) transketolase X3
B) transketolase-transketolase-transaldolase
C) transketolase-transaldolase-transketolase
D) none of the above
C
Which of the following is NOT true of the transketolase and transaldolase reaction?
A)
Transketolase transfers a 2 carbon unit from ketose donor to aldose acceptor
B) both involve the participation of a ketose donor and acceptor
C) Transaldolase involves the transfer of a 4 unit carbon unit from ketose donor to an aldose acceptor
D) all of the above are true
C; that’s transketolase
Which products from PPP can enter glycolysis?
– F6P and glyceraldehyde-3-phosphate
summarize phase 1 and phase 2 of PPP
– Phase 1 - oxidative - glucose 6-P converted to ribulose 5-P with NADPH as a byproduct
– Phase 2 - nonoxidative – ribulose 5-P converted to glyceraldehyde 3-P and fructose 6-P