Carbohydrate Metabolism 2 Flashcards
what is the pentose pathway important for
important for synthesis of:
- fatty acids (generation of NADPH for reductive biosynthesis
- nucleotides (RNA,DNA- formation of ribose-5 phosphate)
what is the committed step in the pentose phosphate pathway?
dehydrogenation of Glucose 6-phosphate
what is glycogen synthesised from
glucose
when and why is glycogen synthesised in liver
when: synthesised in fed state
why: storage for blood glucose maintenance
why is glycogen synthesised in muscle
storage for local energy production (only used by muscle)
why is glycogen not good for storage on itself
has a branched structure
water has to be complexed with it for storage
what is gluconeogenesis
synthesis of glucose from a noncarbohydrate source (reversal of glycolysis) :
- lactate
- pyruvate
- glycerol (breakdown product of triglycerides)
- certain amino acids
where does gluconeogensis occur
mainly in the liver
in kidneys during prolonged starvation
what three reactions are not reversible in glUCONEOGENESIS AND why
- Hexokinase
- PFK/ phosphofructokinase
- Pyruvate Kinase
all involve use of ATP
what is the fate of the three irreversible glycolysis reaction in gluconeogenesis
enzymes are made which bypass (reverse) these reactions
How is hexokinase bypassed
Bypassed by glucose 6 phosphatase (made in the liver)
How is PFK bypassed
Bypassed by fructose 1,6-biphosphatase
expression of what stimulates glucose 6 phosphatase production
adrenaline and glucocorticoids
expression of what suppresses glucose 6 phosphatase production
insulin
where is glucose 6 phosphatase enzyme found in
found in the lumen of ER
