1: Glycolysis Flashcards
Overall equation for glycolysis
1 glucose -> 2 pyruvate + 2 ATP + 2 NADH
Pyruvate fate in anaerobic vs aerobic glycolysis
Anaerobic: forms lactate
Aerobic: TCA cycle and oxphos
Cells that do glycolysis vs gluconeogenesis
Glycolysis: all cells
Gluconeogenesis: liver, kidney, small intestine
Three phase names for glycolysis
Investment, splitting, payoff
Three monosaccharides that can be used for glycolysis
Glucose, galactose, fructose
Why is glucose important?
Only fuel for RBCs + only fuel for brain under non-starving conditions
Where GLUT1, 2, 3, and 4 are found
GLUT1: ubiquitous; high in RBC and brain
GLUT2: liver
GLUT3: neurons
GLUT4: skeletal muscle, heart, adipose
Affinity and Km relationship
Affinity and Km are inversely proportional
Affinity for each GLUT
GLUT1: high affinity
GLUT2: low affinity
GLUT3: high affinity
GLUT4: medium affinity
Which GLUT is insulin dependent?
GLUT4
What is the significance of forming G6P from glucose?
Traps glucose in the cell
Three regulated enzymes in glycolysis
- Hexokinase/glucokinase
- PFK-1
- Pyruvate kinase
Three overall things that influence activity of the three checkpoints in glycolysis
- Energy status (ATP/AMP)
- Fed status (glucose)
- Hormone status (insulin, glucagon)
Hexokinase vs glucokinase: location and affinity
Hexokinase: all cells; high affinity
Glucokinase: liver and pancreatic B cells; low affinity
One thing that inhibits hexokinase and glucokinase
G6P (its product)
Three molecules that activate PFK, three that inhibit it
Activate: AMP, F2,6BP, insulin
Inhibit: ATP, citrate, glucagon
Two activators of pyruvate kinase and three inhibitors
Activators: F1,6BP, insulin
Inhibitors: ATP, alanine, glucagon
What happens to PEP when pyruvate kinase is inhibited?
PEP goes into gluconeogenesis
Which cell type is most effected by defective glycolysis enzymes
Those that lack mitochondria (ex: RBCs)
What is the major clinical presentation involved in defective glycolysis?
Hemolytic anemia
Which enzyme is linked to 95% of glycolysis-related anemias
Pyruvate kinase
Type I vs Type II DM
I: loss of pancreatic B cells -> insulin deficiency
II: insulin resistance
Two clinical markers of hemolytic anemia
- Elevated lactate dehydrogenase
2. Unconjugated bilirubin
Fanconi-Bickel syndrome: mutation and what it causes
Mutation in GLUT2; unable to uptake glucose, fructose, and galactose
