Stage 1 - Glycolysis Flashcards
Where does glycolysis occur?
Cytoplasm
What does the complete oxidation of glucose produce?
CO2 and H2O
What is the end product of glycolysis?
Pyruvate
What does pyruvate get oxidized to in aerobic setting?
CO2
What does pyruvate get oxidized to in anaerobic setting?
ethanol or lactate
Why does glucose need a transporter?
It is highly polar
What catalyzes glucose import?
GLUTs
What does insulin do? What happens in diabetes?
stimulate GLUT mediated glucose uptake
blood glucose isn’t taken up to cells adequately
What are the first 5 reactions in glycolysis?
Prep phase
ATP is used
What are the second 5 reactions in glycolysis?
Payoff phase
ATP is produced (net generation of ATP)
Glycolysis first reaction
cofactor
enzyme
what happens
Glucose->glucose 6 phosphate
ATP->ADP
hexokinase
*irreversible
phosphorylation of glucose
Glycolysis second reaction
cofactor
enzyme
what happens
glucose 6 phosphate->fructose 6 phosphate (ketose/hemiketal)
none
phosphohexose isomerase
glucose is isomerized into fructose
Glycolysis third reaction
cofactor
enzyme
what happens
fructose 6 phosphate->fructose 1,6-bisphosphate
ATP->ADP
PFK-1
2nd phosphorylation (priming)
Glycolysis fourth reaction
cofactor
enzyme
what happens
fructose 1,6-bisphosphate->dihydroxyacetone phosphate
none
aldose
The 6C fructose is split into 2 3C units
DHAP is immediately hydrolyzed into G3P
Glycolysis fifth reaction
cofactor
enzyme
what happens
dihydroxyacetone phosphate->G3P
none
triose phosphate isomerase
interconversion of triose phosphate
Glycolysis sixth reaction
cofactor
enzyme
what happens
G3P->1,3-bisphosphoglycerate
NAD+->NADH+H+
G3P dehydrogenase
Energy key of glycolysis - the G3P is bound to cys residue on G3P dehydrogenase and oxidized to enzyme bound thioester which is attacked by Pi
Glycolysis seventh reaction
cofactor
enzyme
what happens
1,3-bisphosphoglycerate->3-phosphoglycerate
ADP->ATP
phosphoglycerate kinase
substrate level phosphorylation, 2 ATP per 1 glucose, the free E of anhydride bond is recovered in form of ATP
Glycolysis eighth reaction
cofactor
enzyme
what happens
3-phosphoglycerate->2-phosphoglycerate
none
phosphoglycerate mutase
a functional group is shunted between 2- and 3- OH groups
Glycolysis ninth reaction
cofactor
enzyme
what happens
2-phosphoglycerate->phosphoenolpyruvate
H2O leaves
enolase
eliminates H2O to create double bond
creation of the second high energy molecule
Glycolysis tenth reaction
cofactor
enzyme
what happens
phosphoenolpyruvate->pyruvate (enol form)
ADP->ATP
pyruvate kinase
quickly changes to keto form to decrease concentration of reaction product
Glycolysis tenth reaction pt 2
cofactor
enzyme
what happens
pyruvate (enol form)->pyruvate (keto form)
none
tautomerization
gives rise to large and negative delta G
What does the Cori cycle do?
Recovery of strenous activity - uses lactic acid produced from glycolysis and moves it to the liver via the blood to turn into glucose which is returned to muscles.
What does alcoholic condensation do? What is the ultimate electron acceptor?
Yeast converts pyruvate to ethanol + CO2. Not in humans. NAD+ is regenerated allowing glycolysis to continue.
acetaldehyde
What happens to pyruvate after glycolysis in aerobic conditions?
ETC reoxidizes NADH with O2 and pyruvate will be oxidized to CO2
What transports pyruvate into mitochondria?
transporter protein
Transporter protein - What does the malate aspartate shuttle transport? What enzyme helps?
Transfers NADH reducing equivalents from cytoplasm to mitochondrial matrix.
Malate dehydrogenase
Transporter protein - G3P shuttle
Uses FAD to oxidize G3P, resulting in FADH2
What 5 coenzymes does the pyruvate dehydrogenase complex need?
NAD+, FAD, CoA, TPP, lipotate
What is the reaction that connects glycolysis to the citric acid cycle?
Pyruvate dehydrogenase complex
Write a balanced equation for the Pyruvate dehydrogenase complex.
What are the cofactors?
Pyruvate –> Acetyl CoA
NAD+->NADH +H+
CoASH–>
People with beriberi, a disease caused by thiamine (vitamin B1) deficiency, have elevated levels of blood pyruvate. How is this effect related to a deficiency of thiamine?
The lack of thiamine leads to thiamine pyrophosphate not being utilized from the lack of the enzyme thiamine pyrophosphate. The carboxylation of a-keto acids can not occur leading to an elevated blood pyruvate.
