Glycogen! Gluconeogenesis! Pentose phosphate pathway! Flashcards
different possible fates of glucose-6-phosphate
two major glycogen storage sites ?
liver and muscle
glycogen structure ? glycogenin?
glucose units are added in alpha 1-4 linkages to non-reducing ends. glucose units branch off in alpha 1-6 linkages.
glycogen synthesis pathway ?
glycogen synthesis –> illustrate structure
indicate the two forms of glycogen synthase and explain how glucagon and insulin deal with both of them.
FED state –> insulin promotes MORE of the ACTIVE state and LESS of the INACTIVE state.
glycogen synthase has two forms: active and inactive; both of which are activated by G-6-P.
glycogen break down and the enzymes emplyed ?
allosteric regulation of glycogen phosphorylase?
ATP and glucose reduce activity.
AMP activates activity.
two states of glycogen phosphorylase > how is it allosterically regulated by modulators/inhibitors?
glycogen phosphorylase has two forms (more active and less active). both are activated by AMP and inhibited by ATP and glucose.
coordinate regulation of glycogen synthesis ?
FED state –> insulin promotes the more active form of glycogen synthase and promotes the less active form of glycogen phosphorylase.
What happens when the fast period exceeds the capacity of the liver glycogen pool to provide glucose to maintain appropriate blood glucose levels?
gluconeogenesis !
in what step do glycogenolysis and gluconeogenesis converge ? what is the significance of that step?
they converge in the step at which G-6-p phophatase converts G-6-P into glucose. it’s significant since a defect in that step would impair both glycogenolysis and gluconeogenesis, while a defective enzyme in a step down the pathway or earlier in the pathway would preferntially affect either of the two processes.
gluconeogenesis substrates ?
Substrates:
• Lactateandpyruvate
• Fructose
• Someaminoacids(e.g.,alanine) • Glycerol
irreversible steps of glycolysis ?
possible routes to surpass the pyruvate kinase step in gluconeogenesis ?
which Pyruvate kinase surpass route would prefentially be undergone by pyruvate ?
there are two possible steps in the pathway that generate NADH: lactate to pyruvate and malate to oxaloacetate. generating reducing equivalents in necesary to bypass the step from 1,3-bisphosphoglycerate to to glyceraldehyde-3-phophate. the preferred pathway will generate at least 1 NADH.
allosteric role of acetyl coA in gluconeogenesis
role of counter-regulatory hormones in bypassing the PFK-1 step in gluconeogenesis
how does the liver bypass the last step G6P to glucose in gluconeogenesis ?
another possible solution for the mechanism of dephosphorylating glucose to bypass the last step in gluconeogenesis in the liver ?
activators and inhibitors of main regulatory steps of glycolysis and gluconeogenesis
ATP equivalents of gluconeogenesis ?
interplay between adipose and liver in FASTED state ?
interplay between muscle and liver in FASTED state ?
Cori cycle
interplay between muscle and liver in starvation ?
alanine cycle –> breakdown of muscle protein mass
a way to buffer cell’s ATP at times of high energy demand
fates of G-6-P
significance of pentose phosphate pathway ?
generates reducing equivalents NADPH. The NADPH in turn maintains the supply of reduced glutathione in the cells that is used to mop up free radicals that cause oxidative damage.
PPP book image
UDP-glucose in biosynthesis
UDP-glucuronate ?
Bilirubin (formerly referred to as haematoidin) is the yellow breakdown product of normal heme catabolism, caused by the body’s clearance of aged red blood cells which contain hemoglobin
adding a glucuronic acid moiety is a way to modify molecules to make them more soluble or detoxify them.
