module 2- glycolysis Flashcards
where does metabolism occur in eukaryotic cells
cytosol
what are the inputs & outputs for glycolysis
1 glucose in, 2 pyruvate out
Is ATP consumed or produced during 1st stage of glycolysis? And how many ATP molecules?
consumed, 2
is ATP consumed or produced during 2nd stage of glycolysis? And how many ATP molecules?
produced, 4 ATP per molecule of glucose
Glycolysis generates a net of ( ) ATP per molecule of glucose
2
is glycolysis an anaerobic or aerobic process?
anaerobic
steps 1-4 are energy ( ) steps
consuming
steps 5-10 are energy ( ) steps
producing
what is the regulatory enzyme of glycolysis
phosphofructokinase (PFK)
what is the regulatory reaction in glycolysis & what enzyme is involved?
fructose 6-P -> fructose 1,6-BP
enzyme: PFK
how does glucose enter the body?
in form of starch
what reaction is substrate level phosphorylation
PEP -> pyruvate
what enzyme is an allosteric activator of PFK in the liver?
fructose 2,6-BP
what are the 3 fates of pyruvate?
1) acetaldehyde -> ethanol
2) lactate
3) acetyl CoA -> further oxidation
which fate of pyruvate produces the most energy?
acetyl CoA
fermentation is an (anaerobic/aerobic) process
anaerobic
what enzyme converts pyruvate into acetaldehyde
pryuvate decarboxylase
what enzyme converts pyruvate ->lactate
lactate dehydrogenase
lactate lowers pH of muscle which inhibits what enzyme?
PFK
what enzyme converts pyruvate -> acetyl CoA
pyruvate dehydrogenase complex
net products of glycolysis
2 pyruvate + 2 ATP + 2 NADH + 2H + 2 H2O
are reversible or non-reversible steps in glycolysis regulated?
non-reversible
T or F: galactose & fructose are both metabolized by glycolysis but enter pathway at different points
T
fructose is a component of ( ) and galactose is a component of ( )
sucrose, lactose
where does galactose enter glycolysis
at glucose 6-P
lactose intolerant is due to ( ) in lactase
deficiency
where does fructose enter glycolysis?
enters from the liver into DHAP or GAP
T or F: excessive fructose consumption can lead to obesity, fatty liver & type 2 diabetes
T
2 major roles of glycolysis
1) degrade glucose to generate ATP
2) provide building blocks for biosynthetic processes
what 3 enzymes control the rate of glycolysis via the 3 irreversible reactions
1) hexokinase
2) PFK
3) pyruvate kinase
why is glycolysis termed an anaerobic process?
b/c there is no requirement for oxygen
T or F: PFK is controlled allosterically
T
drop in muscle pH ( ) PFK & activates ( )
inhibits, ATP
hezokinase catalyzes ( ) which ( ) hexokinase allosterically
glucose 6-P, inhibits
pyruvate kinase is allosterically ( ) by ATP and ( ) by fructose 1,6-BP
inhibited, activated
increase in fructose 1,6-BP =
increase in pyruvate kinase activity
liver function
maintain glucose levels in the blood
what is glucose stored as?
glycogen
T or F: PFK regulation differs in muscle vs liver
T
what is the inhibitor of PFK in the liver?
citrate
high levels of citrate = metabolized glucose is ( )
slowed
increase of glucose in blood = fructose 6-P ( )
increases
what enzyme needs to be activated to handle increase in glucose in the blood?
PFK
what is the allosteric activator of PFK?
fructose 2,6-P
glycolysis is accelerated when glucose is ( )
abundant
glycolysis uses what type of feedback system?
feedforward
where is hexokinase regulated?
liver
what is glucokinase & its role?
isoform of hexokinase, it phosphorylates glucose
how does glucokinase differ from hexokinase (2)
1) glucokinase has 50 fold higher Km than hexokinase
2) glucokinase is not inhibited by its product (glucose 6-P)
glucose 6-P is formed only when glucose is ( )
abundant (after a meal)
what enzyme does glucose 6-P inhibit?
hexokinase
increase in fructose 1,6-BP = ( ) in pyruvate kinase activity
increase
decreased pH in the muscle ( ) PFK
inhibits
what is hexokinase inhibited by in the muscle?
glucose 6-P
what is pyruvate kinase inhibited by in the muscle? and what is it activated by?
ATP, fructose 1,6-BP
what is PFK inhibited by in the liver? and what is it activated by?
citrate, fructose 2,6-BP
