Glycolysis Flashcards
Glycolysis occurs in
cytosol
Decreased function of glucokinase is assciated with
Maturity onset diabetes of the young
Fructose-6-phosphate can be converted into Fructose-2,6-bisphosphate by the enzyme
Phosphofructokinase 2
Fructose 2,6 bisphosphate induces glycolysis by upregulating the enzyme
PFK1
which converts fructose-6-phosphate to fructose 1,6 phosphate
PFK1 is inhibited by
Citrate
ATP
(Metabolites from ETC and Krebs)
In the well fed state, insulin is high which increases fructose 2, 6 phosphate utilized by both muscle and liver leading to increased hepatic
Glycolysis
On a fasting state, glucagon levels are high which decreases fructose 2,6 bisphosphate and will halt hepatic glycolysis and increase
Gluconeogenesis
Fructose 1,6 bisphosphatase converts fructose 1,6 phosphate to fructose 6 phosphate which allows liver to produce glucose and is inhibited by decreased
If fructose 2,6 bisphosphates is decreased, skeletal muscles are starved glucagon levels are high, hepatic gluconeogenesis is
fructose 2,6 bisphosphate
increased
allows liver to break down AA and other products to create glucose
A drug decreases hepatic concentration of fructose 2,6 bisphosphate.
How will this drug likely alter the activity of aspartate transaminase (converts asparate -> oxaloacetate)
Decreased fructose 2,6 bisphosphate results in gluconeogenesis
If gluconeogenesis is increased, there is increased catabolism of amino acid and glycerol
Asparate transaminase breaks down aspartate to oxaloacetate which increases during gluconeogenesis to make glucose
Increased activity of aspartate transaminase
Decrease in fructose 2,6 bisphosphate upregulated production of fructose 1,6 bisphosphatase resulting in increased production of fructose 6 phosphate for glucose and increased
Gluconeogenesis
In RBCs, 1,3 bisphosphoglycerate from GDP can be converted to
via the enzyme
2,3 bisphosphoglycerate
2,3 BPG
BPG mutase
with loss of ATP
this regulates oxygen delivery to tissue, binds to hemoglobin and decreases hemoglobin affinity to tissue
Deficiency of pyruvate kinase (Phosphoenolpyruvate -> Pyruvate) leads to decreased ability of RBCs to pump cations against concentration gradient and are unable to maintain homeostasis
Decreased ATP resulting in hemolysis
If there is enough oxygen, pyruvate is converted into
Acetyl coa
If there is insufficient oxygen, pyruvate is converted into
Lactate
9 year old/male History of anemia due to enzyme deficiency Splenomegaly Conjunctival pallor Elevated reticulocyte count Hemolytic anemia
Pyruvate kinase converts PEP to pyruvate
If pyruvate kinase is deficient, it is unable to pump cations out of cell due to dec ATP leading to decreased homeostasis and HEMOLYSIS
Pyruvate kinase deficiency
First step in glycolysis
Irreversible
Uses up energy
Glucose -> glucose 6 phosphate by Hexokinase and Glucokinase
Addition of phosphate
Step 2:
Rearrangement of covalent bonds
Glucose 6 phosphate -> Fructose 6 phosphate by phosphoglucose isomerase
3rd step:
Irreversible
Second energy consumption step
First committed step
Fructose 6 phosphate -> Fructose 1,6 bisphosphate by Phosphofructokinase 1
Step 4:
Splitting of 6 to 3 carbon sugars
Fructose 1,6 bisphosphate -> GDAP (glyceraldehyde-3 phosphate) + DHAP (dihydroacetone phosphate)
by Fructose bisphosphate aldolase
Step 5
Isomerization
DHAP -> GDAP by triosephosphate isomerase
2 GDAP
2 ATPs consumed
Step 6:
Energy generation
Inhibited by Arsenic
GDAP -> 1,3 bisphosphoglycerate
by Glyceraldehyde phosphate dehydrogenase
2 NADH
Step 7:
Reversible
Energy generating
1,3 bisphosphoglycerate -> 3 phosphoglycerate
By Phosphoglycerate kinase
Transfer of phosphate
+ ATP
Step 8:
3 phosphoglycerate -> 2 phosphoglycerate
By Phosphoglycerate mutase
Step 9:
Lyase
Inhibited by Flouride
Dependent on Mg or Mn
2 phosphoglycerate -> Phosphoenolpyruvate
By Enolase
Step 10
Irreversible
Generation of ATP
Phosphoenolpyruvate -> Pyruvate
By Pyruvate kinase
End product of Glycolysis from 1 glucose molecule
2 NADH
4 ATP
2 Pyruvate
Glucose and maltose enters glycolysis by
Step 1 Glucose -> Glucose 6 phosphate
Starch, Galactose-1 phosphate, Galactose and Lactose enter glycolysis by
Second step: Glucose 6 -> Fructose 6 phosphate