Glycolysis Flashcards
What is GLUT1?
a housekeeping glucose transporter with a low Km
found in all cells including RBCs which depend solely on glucose for fuel
what is GLUT5?
a fructose transporter in the liver or small intestines
What is GLUT2?
high Km for glucose
presence in liver means liver will take up glucose when blood glucose concentration is raised such as after a meal
allows for the export of glucose from the liver in the fasted state
What is GLUT3?
low Km glucose transporter in the brain
What is GLUT4?
In adipose and muscle tissues
Insulin dependent translocation to plasma membrane
increases uptake 20 fold
What would you expect in a person without GLUT2?
Inability of liver to uptake excess glucose when blood glucose is high
Functioning GLUT2 allows for the export of glucose from liver in the fasted state
What links Glycoylosis to other pathways?
Glucose 6 P
What is the enzyme in the first committed step of glycolysis?
Phosphofructokinase I
by adding the PO4, the glucose is now trapped inside the cell
What is substrate level phosphorylation?
…
What does Glycolysis consume?
glucose
2 ADP
2 NAD+
2 Pi
What are the products of Glycolysis?
2 pyruvate 2 ATP 2 NADH 2 H+ 2 H20
Hexokinase IV
only in liver
works when glucose concentration is high
has very high Km = 10^-2
PFK1
metabolically irreversible
critical regulatory point
first committed step of glycolysis
PFK2
regulatory molecule for PFK1
ATP is a substrate AND ???? for ????
Allosteric inhibitor for PFK1
NAD+ is reduced to
NADH
What is a site for Arsenic poisoning?
AsO4 can substitute for PO4 creating a futile cycle
Under aerobic conditions, what is the fate of pyruvate?
Acetyl CoA
Under anaerobic conditions in microorganisms, allows Pyruvate conversion to …
Ethanol
Under anaerobic conditions what do our muscles convert pyruvate to?
Lactate
what must you recycle to keep glycolysis running?
NADH must be converted back to NAD+ to keep glycolysis running
when ATP is needed
glycolysis is activated
what inhibits Hexokinase?
excess G6P
what ramps up PFK1?
AMP
F26BP
what inhibits PFK1?
ATP
citrate
What induces Pyruvate kinase ? inhibits?
F1,6 BP - induces
ATP - inhibits
What induces Pyruvate dehydrogenase? inhibits?
ADP and Ca+2 - induce
NADH and Acetyl CoA - inhibit
what is F 2,6 BP?
allosteric activator of PFK1 that opposes ATP inhibition
synthesized by PFK-2 from F6P
has kinase and phosphatase domain
can be regulated by serine-threonine protein kinases
For PFK-2,in skeletal muscle, when a high concentration of F6P is present, this activate the kinase and inhibit the phosphatase thereby
increasing concentration of F2,6 BP and activating glycolysis
increased NADH concentration prevents pyruvate oxidation in the TCA cycle and directs …
pyruvate to lactate
What is the Pasteur effect?
slowing of glycolysis in the presence of oxygen
more ATP is produced under aerobic conditions than under anaerobic conditions, therefore less glucose is consumed aerobically
