MTC Week 6 Flashcards
what are the net overall products of glycolysis?
2x pyruvate
2x ATP
2x NADH
in which state is glycolysis a major source of energy?
fed-state
where in cells do these reactions occur?
cytosol
how is energy involved differently in steps 1-5 of glycolysis vs 6-10?
Steps 1-5: Energy-investing reactions
Steps 6-10: Energy-harvesting reactions
which steps are irreversible?
1, 3, 10
starting from the molecule glucose, state the molecule formed, the action and the enzyme used in step 1 of glycolysis
starts from glucose
Reaction: ATP to ADP + a phosphate
Enzyme: Hexokinase/glucokinase in the liver
Molecule formed: glucose 6 phosphate
state the molecule formed, the action and the enzyme used in step 2 of glycolysis
Carbonyl group from C1 to C2
Enzyme: hexose isomerase/ phosphohexose isomerase
Molecule: fructose 6 P
state the molecule formed, the action and the enzyme used in step 3 of glycolysis
Reaction: ATP to ADP + a p
Enzyme: phosphofructokinase
Molecule: fructose 1,6-bisphophate
state the molecule formed, the action and the enzyme used in step 4 of glycolysis
Forms Molecules 2 three carbon sugar (triose) phosphates
- Dihydroxy-acetone phosphate (DHAP)
- Glyceraldehyde 3-phosphate (G3P)
Enzyme: aldolase (cleaves)
state the molecule formed, the action and the enzyme used in step 5 of glycolysis
Dihydroxy-acetone phosphate is converted to Glyceraldehyde 3-phosphate
- Enzyme: Triose phosphate isomerase
state the molecule formed, the action and the enzyme used in step 6 of glycolysis
Reaction: NAD to NADH2
Free inorganic phosphate (Pi) onto C1
Enzyme: glyceraldehyde 2-phosphate dehydrogenase
Molecule: 1,3-bisphosphoglycerate (1-3-PGA) x2 molecules
state the molecule formed, the action and the enzyme used in step 7 of glycolysis
- Reaction: ADP to ATP
- Molecule: 3-phosphoglycerate (3PG)
- Enzyme: 3-phosphoglycerate kinase
state the molecule formed, the action and the enzyme used in step 8 of glycolysis
- Phosphate group of 3PG is moved from C2 to C3
- Molecule: 2-phosphoglycerate
- Enzyme: phosphoglycerate mutase
state the molecule formed, the action and the enzyme used in step 9 of glycolysis
- Removes water from 2PG
- Molecule: phosphoenolpyruvate (PEP)
- Enzyme: enolase
state the molecule formed, the action and the enzyme used in step 10 of glycolysis
- Molecule: pyruvate
- ADP to ATP
- Enzyme: pyruvate kinase
how is glycolysis regulated with glucokinase and hexose
(Step 1)
Glucokinase (liver): is induced by insulin, occurs as glucose levels are high to store glucose as glycogen
Hexose: allosteric inhibition by G6P
how is glycolysis regulated with PFK1
(step 3)
allosteric regulation of PFK1
what are the 3 allosteric activators of PFK1
F2,6BP
ADP
AMP
what are the 2 allosteric inhibitors of PKF1
ATP (binds PKF1 and decreases its affinity for F6P)
Citrate
what are the 2 allosteric regulators of PKF1
PFK2 (catalyses phosphorylation of F6P to F2,6BP)
F2,6BP (stimulates PKF1)
how does insulin and glucagon affect PFK2
Insulin regulation: stimulates PFK2 activity → increases F2,6BP → activates PFK1
Glucagon regulation: stimulates F2,6Bpase activity → decrease F2,6BP → inhibits PFK1
how is glycolysis regulated with PK
(Step 10)
allosteric regulation by PK activity
what are the 2 allosteric activators of PK
F1,6BP (upregulates PK - feed forward stimulation)
ADP
what are the 2 allosteric inhibitors of PK
ATP
Alanine
how does insulin and glucagon regulate PK
insulin stimulates dephosphorylation of PK (active form)
glucagon stimulates phosphorylation of PK (inactive form)
where is fructose metabolized
liver
describe the steps of fructose metabolism
Fructokinase (FK) form Fructose-1-phosphate (F1P)
F1P is cleaved by Aldolase B (ALD B) to DHAP and glyceraldehyde (GA).
DHAP goes into glycolysis
GA is phosphorylated by Triose kinase to form glyceraldeyhde-3-phosphate (G3P), & goes into glycolysis.
TPI: Triosephosphate Isomerase
what is the function of lactase and where is it found
to digest milk
located in the microvilli cells of the small intestine
what are the 3 enzymes required to breakdown galactose
Galactokinase (GALK): galactose to galactose-1-phosphate.
Galactose-1-phosphate uridyltransferase:
Transfer of UDP from UDP-glucose (glycogenesis).
UDP-galactose-4’-epimerase (GALE): Reversible epimerization of UDP-glucose to UDP-galactose
