Glycolysis Flashcards
What does glycolysis metabolize?
1 molecule of Glucose to 2 molecules of Pyruvate to generate 2 molecules of ATP
What monosaccharides make up sucrose?
Glucose and Fructose
What monosaccharides make up lactose?
glucose and galactose
What is the only “fuel” RBC’s can use?
Glucose
GLUT 1?
Expressed highly in brain and RBC’s has high affinity (low Km), unregulated
GLUT 2?
Main glucose transporter in liver, low affinity (high Km), unregulated
GLUT 3?
Main transporter in neurons, high affinity (low Km), unregulated
GLUT 4?
Present in skeletal muscle, heart, and adipose. Insulin dependent
Where does glycolysis occur?
Cytoplasm
What is the first step in Glycolysis where ATP is used?
To convert Glucose to G6P with hexokinase
What is the second step in glycolysis where ATP is uded?
To convert Fructose-6-Phosphate to Fructose-1,6-bisphosphate using PFK
What is the first stage in glycolysis where ATP is made?
When going from 1,3-bisphosphoglycerate to 3-phosphoglycerate using Phosphoglycerate kinase
What is teh second stage where ATP is made in glycolysis?
In the conversion of phosphoenolpyruvate to pyruvate using pyruvate kinase
The first stage of Glycolysis begins and ends with what?
begins with the phosphorylation of glucose and ends with isomerization of dihydroxyacetone phosphate to Glyceraldehyde-3-phosphate (GAP)
What three reactions does stage one of glycolysis involve?
Phosphorylation, isomerization, phosphorylation again
Step 1 in Glycolysis is?
Phosphorylating Glucose with Hexokinase to G6P. This step consumes ATP. (glucokinase is used in liver)
Step 2 in Glycolysis?
Isomerize G6P to Fructose-6-phosphate (F6P) using phosphoglucoisomerase
Step 3 in Glycolysis?
F6P is phosphorylated to Fructose-1,6-bisphosphate (F1,6BP) using PFK. ATP is consumed. PFK is the rate limiting enzyme of glycolysis
Step 4 Glycolysis?
F1,6BP is broken to G3P and DHAP by aldolase. Equilibrium favors G3P so most is converted back.
Step 5 Glycolysis?
DHAP isomerized to G3P by the enzyme triose phosphate isomerase
Step 6 Glycolysis? (Stage 2)
GAP (G3P) undergoes oxidative phosphorylation by Glyceraldehyde-3-phosphatedehydrogenase to form 1,3-BPG. This step generates NADH for the electron transport chain.
Step 7 Glycolysis?
1,3-BPG is converted to 3-phpsphoglycerate (3-PG) by phosphoglycerate kinase. This step produces ATP.
Step 8 Glycolysis?
3-PG is converted using phosphoglycerate mutase into 2-PG.
Step 9 Glycolysis?
2-PG is dehydrated to form PEP, which is unstable. This is done by enolase.
Step 10 Glycolysis?
PEP is converted to Pyruvate (stable ketone) using pyruvate kinase, an irreversible step. This also creates ATP
Glucose + ATP –>G6P + ADP + H. What enzyme is missing?
Hexokinase
G6P F6P. What enzyme is missing, what step?
phosphoglucose isomerase, step 2
F6P + ATP—> F1,6BP + ADP + H. What enzyme is missing and what step?
PFK (Rate limiting enzyme), step 3
F1,6BP DHAP + G3P. What enzyme and what step?
Aldolase,Step 4
DHAP G3P. What enzyme and step?
Enzyme triose phosphate isomerase, step 5
G3P + Pi + NAD 1,3BPG + NADH + H. Enzyme and step?
GAPDH Glyceraldehyde-3-phosphatedehydrogenase, step 6
1,3-BPG + ADP 3PG + ATP. What enzyme and step?
Phosphoglycerate kinase, step 7
3PG 2PG. Enzyme and step
Phosphoglycerate mutase, step 8
2PG PEP + H2O. What enzyme and step
enolase, Step 9
PEP + ADP + H —–> Pyruvate + ATP
Pyruvate Kinase, irreversible, step 10
How can pyruvate be reduced to lactate?
With regeneration of NAD+
what are the three outcomes pyruvate can udergo?
Acetyl CoA, Lactate (anaerobic), Acetaldehyde further to Ethanol.
What regenerates NAD+ for glycolysis to continue?
Pyruvate to Lactate
What two monosaccharides can be converted into glycolytic intermediates?
Fructrose and Galactose
What is significant about Fructose metbolism?
It by passes the rate limiting step of PFK, and G3P goes into making triaglycerols.
What are the three major regulatory enzymes?
Hexokinase, PFK, Pyruvate Kinase
