TOPIC 11 ANABOLIC PATHWAYS OBJs Flashcards
glucose can also be metabolised by an alternate pathyway:
pentose phosphate pathway
products of PPP
5-carbon sugars and NADPH
- Two phases to the PPP
- Oxidative phase
- Non-oxidative phase
oxidative phase
– where Ribose-5-P and NADPH are formed
non-oxidative phase
– recycling of pentose sugars into hexose sugars (i.e. Fructose-6-P)
NADH and NADPH are usually involved in
NADH – mainly involved in catabolism
NADPH – mainly involved in anabolic processes and detoxification
- Rapidly dividing cells will consume the ribose-5- P from the oxidative phase
- These include
bone marrow, skin and intestinal mucosa cells
- Ribose-5-P is a precursor for
RNA, DNA, but also other coenzymes (ATP, NADH, FADH 2, CoASH)
- In tissues that mainly need NADPH, R5P can be recycled in the
non-oxidative phase of PPP
- Unique PPP enzymes catalyse _________ & ________ these reactions in non oxidative
transketolase & transaldolase
- The non-oxidative is particularly important in cells where
high levels of ribose-5-P are not required
- Nucleotide synthesis occurs via two key pathways
- Purine nucleotide synthesis (i.e. A, G)
- Pyrimidine nucleotide synthesis (i.e. C, T and U)
nucleotide synthesis is an example of
branched biosynthetic pathways
Purine nucleotide synthesis
starting product in purine biosynthesis
ribose-5-P
Pyrymidine nucleotide biosynthesis
