red cell glycolysis Flashcards
how many ATP can be made per glucose in RBC glycolysis?
2 ATP per glucose
how does glucose enter RBC cells? what keeps it inside?
enters via glucose transporter
phosphorylated in cell so can’t leave
what are the enzymes involved in the phosphorylation of glucose? which enzyme are found in which tissues?
the two enzymes are hexokinase and glucokinase
hexokinase is in all cells
glucokinase is only in liver and pancreatic beta cells
what is the functional difference between hexokinase and glucokinase?
glucokinase has a higher Km for glucose than hexokinase
this allows for its action to be proportional to the levels of glucose present in the blood rather than to the enzyme’s ability to process the glucose (very important for pancreatic cell’s ability to sense blood glucose levels)
what are the three alternate pathways of glucose metabolism? in which cells do these pathways occur?
glycolysis
pentose phosphate pathway
glycogen synthesis
all three occur in most but not all cells
what is the glycolysis pathway used for (ie what does it produce)?
ATP and pyruvate production or lactate production
what is the pentose phosphate pathway used to produce?
makes NADPH, ATP and pentose
what is the glycogen synthesis used for?
to store carbohydrate
what determines which glucose pathway is used?
the cell type and the metabolic state
what pathways can RBCs use to metabolize glucose?
glycolysis or pentose phosphate pathways only
what happens to the products of RBC glucose metabolation? what are these products?
the lactate and CO2
how do RBCs regenerate NAD+?
for glycolysis to proceed, NAD+ must be regenerated from NADH
cells that have mitochondria can use O2 to do this but RBCs don’t have mitochondria
instead, lactate dehydrogenase (LDH) regenerates NAD+
form lactose from glucose (muscle cells can also get lactate from glucose if deprived of O2)
what id lactate dehydrogenase (LDH)?
regenerates NAD+ using lactate in RBCs
