Glycolysis Flashcards
When the B cells of the pancrease cannot respond to high blood glucose levels, what has been mutated and inherited?
glucokinase
when does glucokinase become very active?
when there is a higher than normal concentration of glucose
if the mitochondria is absent in red blood cells, how do they get there energy supply?
from glycolysis
what is the most important regulated step?
PFK1
why are the regulated steps irreversible?
they are irreversible because energy is being added in the form of ATP
what is the first rate limiting step?
hexokinase and glucokinase
why does glucokinase need to be phophorylated?
it needs to be phosphorylated, so that it can stay in the liver
after glucose is phosphorylated what is the next step?
it is changed from a aldose to a ketose..by phosphoglucose isomerase
why is the second rate limiting step important?
because it is the committed step
what happens in the 3rd step of glycolysis?
phosphofructokinase adds another phosphate to fructose to create fructose 1,6 bisphosphate
what is PFK-1 inhibited by?
ATP, citrate, Fructose bisphosphotASE-2, glucagon
what activates PFK-1?
Fructose 2,6 bisphosphate, AMP, ADP,PFK-2, insulin
what makes fructose 2,6 bisphosphate?
PFK-2
when insulin come into the cell how does it activate PFK2?
it activates it by dephosphorylating it
what are the bidirectional enzymes?
pfk2(gets dephosphorylated) and fructose bisphosphotase 2 (phosphorylated)
when glucagon is present what happens to PFK2?
PFK2 in phosphorylated and becomes inactive to prevent glycolysis, while fructose 2 bisphosphotase becomes active for gluconeogenesis
what does aldose do to fructose 1, 6 bisphosphate?
it cleaved it into 2 trioses( dihydroxyacetone phosphate and glyceralaldehyde 3 phosphate
where is aldose A present?
in the muscle
where is aldose B present?
in the liver
what does glyceraldehyde 3 phosphate dehydrogenase result in in the energy producing phase?
NADH
since dihydroxyacetone phosphate cannot fed into glycolysis what does it have to form into by triosephosphateisomerase?
glyceraldehyde 3 phosphate
what does phosphoglycerate kinase result in the formation of?
1,3-bisphophosglycerate and ATP (substarte level phosphorylation)
when 1,3 bisphosphoglycerate is formed, why is it important?
it is important because it is a high energy intermediate that results in in the formation of ATP without involving the electron transport chain-
What type of reaction is involved with 1,3-BPG?
it is a substrate level phosphorylation reaction which is important during periods of low oxygen.. hypoxia- this make ATP in its own- it can add a phosphate group directly to ADP to form ATP- without involvment of electron transport chain
what does phosphoglycerate kinase form?
3-phosphoglycerate
what does phosphoglycerate mutase produce?
2- phosphoglycerate
what does arsenate inhibit?
stops the formation of 1,3 bisphosphate by inhibiting glyceraladehyde phosphate dehydrogenase
Arsenic disrupts ATP production through several mechanisms. At the level of the citric acid cycle, arsenic inhibits pyruvate dehydrogenase and by competing with phosphate it uncouples oxidative phosphorylation, thus inhibiting energy-linked reduction of NAD+, mitochondrial respiration, and ATP synthesis.
why is phosphoenolpyruvate a high energy compound?
Its a high yield energy compound that results in the formation of ATP, without the involvment of the ETC in mitochndria(substrate level phosphorylation)
why are substrate level phosphorylation reactions important during periods of low oxygen(hypoxia)?
because they can produce ther own ATP without the involvment of the ETC in mitochondria
which enzyme results in the formation of the 2nd ATP in glycolysis?
pyruvate kinase
what is the result at the end of glycolysis?
2 molecules of pyruvate
what type of reaction is pyruvate kinase?
irreversible
what does fluoride inhibit?
enolase which makes phosphoenolpyruvate(PEP)
which step is the regulated step that is associated with disorders?
the step when phosphoenlpyruvate is converted to pyruvate by pyruvate kinase
where does the cycle began to make two of everything?
at glyceraldehyde-3-phosphate
what are the two conditions that pyruvate can sustain?
aerobic(abundance of O2 and mitochondria), anaerobic(no mitochondria or no oxygen)
what is the function of pyruvate dehydrogenase?
it helps convert pyruvate to AcetylCoA in aerobic respiration
what is the function of lactate dehydrogenase?
it transfers pyruvate to lactate in anaerobic coditions
what cycle does acetyl CoA enter?
TCA Cycle( Citric acid cycle, kreb cycle)
what cycle does lactate enter into?
the liver via the cori cycle
in gluconeogenesis in the liver what does pyruvate carboxylase form?
oxaloacetate
when is lactate produced?
( by the process of fermentation) during normal metabolism and exercise.
when lactate accumulates in the muscle what happens to the Ph?
the pH will drop and may manifest as cramps during intense exercise
where does lactate in the muscle and red blood cells go?
it diffuses out of the cell and is taken to the liver where it is used for gluconeogenesis (cori cycle)
what is special about heart muscles when dealing with pyruvate?
the heart muscles convert lactate to pyruvate and later to acetyl CoA, to enable it to enter the TCA cycle.
what may happen with cardiac muscle hypoxia?
results in lactate formation( myocardial infarction)
what type of pathway is glycolysis?
it is a catabolic pathway
what are the three irreversible regulatory steps?
glucokinase/hexokinase, phosphofructokinase-1, pyruvate kinase
how many ATP’s have been produced from glyceraldehyde 3 phosphate dehydrogenase in glycolysis ?
2x3=6, 2 NADH from glyceraldehyde 3 phosphate dehydrogenase
NADH formed from the cytosol is transported into the mitochondria by ?
malate-aspartate or glycerol-phosphate shuttle
how many ATP are used in glycolysis?
2 ATP
what is the total amount of ATP in aerobic glycolysis?
8 ATP
what happens to NADH when lactate is formed?
it is reoxidized to be avialiable for glyceraldehyde 3 phosphate dehydrogenase
how many NADH + H+ are formed in anaerobic glycolysis?
2 (formed in glyceraldehyde 3 phosphate dehydrogenase reaction)
how many ATP’s are used in anaerobic glycolysis?
2
what is the total of ATP in anaerobic glycolysis?
2ATP
in adipose tissues, what is used to provide glycerol components that is used for triacylgylecerol formation?
glyceraldehyde
in red blood cell, where do they get there major energy source?
glycolysis
what does anaerobic glycolysis help produce that will help with unloading for hemeglobin?
2,3 bisphosphoglycerate(2,3-BPG)
what type of deifiency occurs in hemolytic anemia?
erythorcyte pyruvate kinase deificiency
defects in glycolysis would result in blank and blank due to decreased blank?
hemolysis, hemolytic anemia and ATP generation
what is compromised in hemolysis in pyruvate kinase/ hexokinase?
the Na+/K+ ATPase=RBC lysis
what are the factors that tell you that lactic acidosis isa metabolic acidosis?
pH is low, HCO3- is decreased, PCO2 is decreased
when lactic acidosis occurs what can we observe about lactate acidosis?
there is an increased conversion of pyruvate to lactate
what can cause lactate acidosis?
strenuous activity, inherited deficiency of pyruvate dehydrigenase, thiamine deficiency, defect in gluconeogenessis, decreased blood supply resulting in the anaerobic metabolism
WHat is the second most common form of hemolytic anemia due to RBC enzyme deficiency( G6PD)?
pyruvate kinase dificency
what is “warburg effect?”
when most cancer cells use glycolysis as the main source of ATP
patients with pyruvate kinase deficency wil have what affect on 23BPG?
increase unloading and vice versa for hexokinase
what is “flurodeoxyglucose(FDG)”?
used for positrion emission for tumor cells
When PFK2 is inactive what happens to FBP2?
it is activated
what is the role of fuctose 2,6- bisphosphate?
regulation in liver
what is the purpose of glycolysis?
the breaking down of glucose( high energy molecule) to produce energy
what is the cori cycle?
lactate produced by anaerobic glycolysis in the muscles moves to the liver and is converted to glucose, which then returns to the muscles and is metabolized back to lactate.
