Glycolysis Flashcards
powerhouse of cell?
mitochondrial matrix –> where aerobic metabolism occurs
if you havent had breakfast, what do you use as energy source?
fatty acids (fat)
two dehydrogenating reagents
NAD/FAD
fatty acids undergo
beta oxidation (consisting of dehydrogenation rxns)
long fatty acid chain in oxidation..
go through cycle over and overuntil used up –> creates a pool of acetyl coa for tca cycle
c from acetyl coa in tca become….and c from oxaloacetate in tca become….
acetyl coa –> new oxaloacetate
oxaloacetate –> co2
oxygen comes from
water
in etc oxygen becomes
water
why cant nadh and oxygen react directly in etc ?
because of the activation energy barrier….there is no enzyme to allow direct e transfer
how do protons in etc get across lipid bilayer?
ATP synthase allows protons to move down their gradient –> as they travel down, conformational changes of the synthase resynthesizes ATP (this is ox. phosphorylation)
overall glycolytic path
d-glucose –> 10 steps catalyzed by 10 enzymes –> 2 pyruvate
anaerobic fate of pyruvate?
lactic acid
glycolysis is a net ____ rxn that takes place through ____ rxns
oxidation; dehydrogenation
rbc atp production?
rbc dont have mitochondria so glucose is converted to lactate –> atp from glycolysis is the only source of atp for those cells
glucose storage polymer
glycogen
fastest source of G6P when you need energy quick
atp yield from complete combustion of one glucose
30-32 atp
steady state ATP/ADP+AMP ratio
maintained far from equilibrium –> very exergonic!
ATP is way higher
equilibrium = death
what happens when ATP/Adp ratio hits equilibrium?
common cause of cell death is oxygen deprivation –>atp system goes to equilibrium –> cell cant maintain itself -> death cascade due to drop in atp
aerobic vs anaerobic glycolysis
a= glucose +2NAD,2ADP,2Pi–> 2 pyruvate + 2nadh,2atp
an=glucose+2adp,2pi –> 2 lactate +2atp
lactic acidosis
too much acid
blood pH goes down - disrupts homeostasis
acidosis in bad circulation vs anemia
bad cir =atp drops, cells use both a and an respiration to restore atp levels –> lactate
anemia= not enough rbc, tissues arent getting enough oxygen to run oxidative phosphorylation so lots of lactate
glucose vs fructose vs pyruvate structure
glucose is an aldose - carbonyl on C1
fructose is a ketose - carbonyl on C2
pyruvate is an alpha keto acid (carbonyl on alpha c)
kinase
adds a phosphate, favorable reaction, uses atp and makes adp
mutase
moves phosphate to another hydroxyl group
how many isomerase reactions in glycolysis?
2
hydratase/dehydratase
add/remove water
aldolase
c-c bond breaks between alpha and beta c; beta becomes carbonyl
aldol condensation
form a c-c bond
dehydrogenase
oxidation
where does glycolysis take place?
cytosol
intermediates and enzymes of glycolysis
- glucose-(hexokinase) - glusoce 6 phosphate
- G6P -(phosphoglucoisomeras) - fructose 6 phosphate
- fructose 6 phosphate -(phosphofructokinase 1) - fructose 1,6,bisphosphate
- fructose 1 6 bisphosphate -(fructo-bisphosphate aldolase) - glyceraldahye3phosphate
- dihydroxyacetone phosphate - (TPI) -glyceraldehyde 3 phosphate 6.glyceraldehyde 3 phosphate (glyceraldehyde phosphate dehydrogenase) - 1,3 bisphosphoglycerate
- 1,3 bpg -(phosphoglycerate kinase pgk) - 3 phosphoglycerate
- 3pg - (phosphoglycerate mutase) - 2 phosphoglycerate
- 2 pg - (enolase) - phosphoenolpyruvate (pep)
- pep - (pyruvate kinase) - pyruvate
which steps use ATP in glycolysis?
1 (hexokinase)
3 (phosphofructokinase)
both irreversible
which steps in glycolysis make atp?
7 (phosphoglyccerate kinase)
10 (pyruvate kinase)
after step 1 of glycolysis, can g6p do anything else?
yes, it can go through glycolysis, or glycogen synthesis, or pentose phosphate pathway
after step 1 is where glycogen can feed into glycolysis
which gly step is the aldose-ketose isomerization?
step 2
g6p –>fructose 6 phosphate
uses phosphoglucoisomerase
which step is the highly regulated commitment step? irreversible
fructose 6 phosphate –> fructose ,6bisphosphate
uses (pfk)phosphofructokinase and atp to adp
g3p dehydrogenase
uses S as a good leaving group
nad –> nadh
aldehyde –>mixed acid anhydride
g3p –>glycerate bisphosphate
which reaction in gly uses an irreversible tautomerization using atp?
10, pyruvate kinase forms pyruvate (keto)
3 irreversible steps of glycolysis
1 (hexokinase), 3(pfk), 10(pyruvate kinase)
**must be bypassed in gluconeogenesis in liver
NAD supply for glycolysis is replenished by…
glyceol 3P and malate/asparate shuttles
nad supply for anaerobic glycolysis is replenished by…
lactate dehydrogenase
3 cytosol-mito transporters that dont exist
oxaloacetate
nad(H)
acetyl coa
2 shuttles for nad/nadh
glycerol phosphate (most tissues) malate aspartate (liver, kidney, heart)
enzyme for g3p shuttle?
glycerol phosphate dehydrogenase
net reaction for glycerol phosphate shuttle
nadh (cyt) + flavoprotein(ox) –> nad+ (cyt) + flavoprotein (red)
flavoprotein accept e
irrevesible
which shuttle requires a transaminase rxn?
malate aspartate shuttle
net reaction for malate aspartate shuttle
nadh (cyt) + nad+(mito) –> nad+ (cyt) + nadh (mito)
how malate aspartate shuttle works?
nadh reduces oxaloacetate into malate and nad+ is regenerated
malate passes through imm via malate shuttle
malate reacts with nad inside to make nadh and oxaloacetate via malate dehydrogenase
e on nadh feed into etc, producing nad+
transaminase rxn takes oxaloacetate and glutamate to make alpaketoglutarate and aspartate
aspartate diffuses across imm into cytosol and a transaminase rxn happens in reverse to make oxaloacetate
net movement of e (reversible)
anaerobic glycolysis
pyruvate + nadh –> lactate + NAD+
uses lactate dehydrogenase
reversible (direction depends on nadh/nad ratio)
cells that produce lactate and cells that use lactate
rbc and working muscles produce it
liver uses it for gluconeogenesis and resting muscle and heart use it as fuel
efficiency vs power
e=atp produced/amount of fuel consumed
p=atp produced/sec
aerobic is more ____ but anaerobic is more____
efficient (15x more atp)
less efficient but potentially 30x faster
if anaerobic is 30x faster, what is the drawback?
more atp/sec uusing glycogen BUT lactic acidosis creates acidic blood and muscles slow down
physiological anaerobic threshold
lactate production by working muscle exceeds rate of utilization by other tissues
aerobic pathway for lactate utilization
lactate –> pyruvate –>acetyl coa –> co2
gluconeogenesis
where? how?
2 lactate enter liver
liver uses 6 atp in gluconeogenesis to produce 1 glucose
cori cycle
glucose –>2 lactate and 2 atp (RBC)
2 lactate +6 atp–> glucose (liver)
quickly more atp is being used than produced
alanine can be made from
pyruvate
serine can be made from
3phosphoglycerate
acetyl coa can make…
fatty acids –> triglycerides
