Glycolysis and Gluconeogenesis 10/8 Flashcards
where does glycolysis take place?
cytoplasm
products of AEROBIC glycolysis are:
pyruvate and lactate (both!)
the 2 phases of glycolysis are
- preparatory phase
2. ATP generating phase
what is the net ATP that gets made in glycolysis
2 ATP (4 total made, 2 were used in the process=2 left over)
can glucose leave the cell once it is phosphorylated?
no! thats why it gets phosphorylated - its fate is then determined
the most highly regulated step in glycolsis involves which enzyme?
PFK1 (phosphofructokinase 1) makes fructose-6-phosphate into fructose-1,6-bisphosphate. has 4 allosteric binding sites!
insulin (promotes/inhibits) glycolysis
promotes
glucagon/catecholamines (promote/inhibit) glycolysis
inhibit
rate limiting enzyme of glycolysis
PFK1
PFK1 exists as ___ isoforms. what are they?
3 isoforms
m-muscle l-liver p-platelets
the 2nd irreversible step in glycolysis is
PFK1 catalyzed (fructose-6-phosphate to fructose-1,6-bisphosphate
PFK1 is allosterically inhibted by
ATP and citrate
PFK1 is allosterically stimulated by
AMP and ADP
Whats the BFD about PFK2?
it has both a kinase domain (n-terminus) and phosphatase domain (c-terminus)
the PFK2 kinase is active when
dephosphorylated by insulin dependent pathway
the PFK2 phosphatase is active when
phosphorylated by glucagon/catecholamine dependent pathway
aldolase gene A: highest expression and pathway its important for
highest expression in muscle
important for glycolysis
aldolase gene B: highest expression and pathway its important for
highest in gluconeogenic tissues (kidney, liver, intestine)
important for fructolysis, glycolysis, gluconeogenesis
aldolase gene C
highest in CNS
what is the function of aldolase?
cleaves 6C substrate into 2 3C products
phosphoglycerate kinase
1,3-bisphosphoglycerate –> 3-phosphoglycerate +ATP
what effect does BPG have on hemoglobin?
causes it to release O2 into tissues (more numerous in areas of high altitudes)
pyruvate kinase
phosphoenolpyruvate –>pyruvate
*irreversible, coupled to ATP synthesis
pyruvate kinase is allosterically activated by
F-1,6-P
pyruvate kinase is allosterically inhibited by
ATP and alanine (indicates theres lots of pyruvate)
PKL is inhibited when
phosphorylated
NAD has to be regenerated. the shuttles to bring it back to the mitochondria are:
- glycerol-phosphate
2. malate-aspartate
which isoform of lactate dehydrogenase favors formation of lactate and NAD?
LDHA
which isoform of lactate dehydrogenase favors formation of pyruvate and NADH?
LDHB (LDH1) - in heart attacks, high serum LDH1
malata/aspartate shuttle
a way of regenerating NADH/NAD so that NAD can be used in glycolysis
what are the substrates for gluconeogenesis?
amino acids, lactate, glycerol
what is gluconeogenesis?
synthesis of glucose from non-carbs
3 irreversible steps of gluconeogenesis are:
- pyruvate –>PEP via OAA (catalyzed by PC and PCK)
- dephosphorylation of fructose-1,6-bisphosphate by FBPase 1
- dephosphorylation of glucose-6-phosphate by G6Pase
