exam 1 glycolysis Flashcards
where does glycolysis happen?
cytosol
what are the products of glycolysis?
ATP, NADH, pyruvate
in fast glycolysis, pyruvate is converted to?
lactic acid and alanine
in slow glycolysis, pyruvate does what?
pyruvate -> mitochondria -> aerobic metabolism
glycolysis yields precursors to?
the aerobic system- krebs and electron transport chain
glycolysis is the only source of metabolic energy in which cells and tissues?
erythrocytes, renal medulla, sperm
what is the preparatory phase of glycolysis?
phosphorylation of glucose- brings glucose in and traps it and then adds a phosphate to it
bis-phosphate implies what?
2 separate phosphates
diphosphate implies what?
2 joined phosphates
1 glucose yields?
2 pyruvates
DHAP converts into?
G3P
what enzyme is needed for glucose - glucose-6-phosphate? (phosphorylation)
hexokinase/glucokinase, uses 1 ATP
what enzyme is needed for isomerization; glucose-6-phosphate into fructose-6-phosphate?
phosphoglucose isomerase- rearranges
what enzyme is needed for phosphorylation of fructose-6-phosphate into fructose-1,6-bisphosphate?
phosphofructokinase-PFK *key rate limiting enzyme
what does the enzyme aldolase do?
splits fructose-1,6-bisphosphate into DHAP and G3P
which enzyme converts DHAP into another G3P?
triose phosphate isomerase
G3P dehydrogenase does what?
oxidizes G3P into 1,3-bisphosphoglycerate (this happens twice)
1,3-bisphosphogylcerate loses a phosphate with what enzyme and what is left?
phosphoglycerate kinase and 3-phosphoglycerate is left *this happens twice creating 2 ATP
which enzyme moves the phosphate from 3-phosphoglycerate to 2-phosphoglycerate?
phosphoglycerate mutase
2-phosphoglycerate into PEP (phosphoenolpyruvate) happens by what type of reaction and with what enzyme?
dehydration reaction and the enzyme is enolase
phosphoenolpyrvuate PEP is a high energy molecule and wants to transfer its phosphate group, what enzyme does this?
pyruvate kinase
any reaction within the cycle that is irreversible uses which type of enzyme?
kinase
what are the key regulatory enzymes of glycolysis?
hexo/glucokinase
PFK
pyruvate kinase
what is an isozyme?
different proteins that catalyze a reaction
hexokinase has how many isozymes?
4
hexokinase 1-3 are used for?
energy production
hexokinase 4 (glucokinase) is used for?
blood glucose homeostasis
hexokinase has high affinity for?
glucose (low Km)
hexokinase is ______ by its product
inhibited
glucokinase is found where?
liver and B cells of pancreas
glucokinase is _______ by its product
NOT inhibited
what is glucokinase stimulated by?
fructose and insulin
glucokinase has a high Km which means?
it takes more reactant to make it go faster
hexokinase is found where?
muscle
what is the rate limiting step of glycolysis?
PFK-phosphofructokinase
what 4 things inhibit PFK?
high energy charge
decreased pH
citrate-krebs cycle
end products or waste products
what is an allosteric enzyme?
ATP binds to the enzyme and decreases its activity
is PFK an allosteric enzyme?
yes
PFK-2 catalyzes what?
formation of fructose-2,6-bisphosphate in a different reaction
what is the most potent activator of PFK-1
fructose-2,6-bisphosphate
phosphorylation of fructose-6-phosphate by PFK-2 yields
fructose-2,6-bisphosphate
what does fructose-2,6-bisphosphate do?
inhibits gluconeogenesis, stimulates glycolysis and is stimulated by insulin
what decreases fructose-2,6-bisphosphate?
glucagon
what does pyruvate kinase do?
catalyzes the 3rd irreversible step in glycolysis
what inhibits pyruvate kinase?
increased alanine, ATP or pyruvate
what stimulates pyruvate kinase?
increased ADP or PEP, fructose-1,6-bisphosphate
when blood glucose is low which hormone is secreted?
glucagon
