pack Flashcards
Which glucose receptor is insulin dependent?
GLUT 4
Where does glycolsis take place?
In the cytoplasm
What are the enzymes for rxn 1, 3, and 10 in glycolsis?
1: Hexokinase
3: phosphofructokinase-1
10: Pyurvate kinase
What happens in rxn 1 of glycolsis?
Hexokinase will add a phosphate from atp on to glucose to form glucose-6-phosphate.
This will trap the glucose inside the cell.
This reaction is feedback inhibted by the accumilation of glucose-6-phosphate.
How is rxn1 different in the liver?
It is induced by glucokinase, bc its purpose is to store glucose. (reduce hyperglycemia)
It is not feedback inhibted (bc we want to store as much glucose as possible when needed)
Glucokinase is induced by insulin
How is rxn1 different in the pancreas?
It is induced by glucokinase in b cells of pancreas
It is used as a sensor (indicator) for glucose to tell the pancrease to release insulin.
What is the difference in affinity and Km for glucose between hexokinase and glucokinase?
Hexokinase: High affinity / Low Km
Glucokinase: Low affinity / High Km
What is the difference in Vmax for glucose between hexokinase and glucokinase?
Hexokinase: Low Vmax
Glucokinase: High Vmax (to reduce Hyperglycemia as fast as possible)
What happens in Rxn 2?
Glucose 6-phosphate will turn into Fructose-6-phosphate
What happens in Rxn 3?
Phosphofructokinase 1 will add another phosphate molecule to Fructose-6-phosphate
turning it into Fructose-1,6-bisphosphate.
This process requires ATP (for the phosphate)
What is the most important control point in glycolsis?
Rxn 3
What is the rate limiting and comitted step in glycolsis?
Rxn 3
What is Rxn 3/phosphofructokinase regulated by?
Rxn 3 is inhibted by the energy level of the cell (The amount of ATP inside the cell)
What is Rxn 1/ Hexokinase regulated by?
The amount of glucose inside the cell
What are the inhibtors of Rxn 3?
Atp, citrate
What are the activators of Rxn 3/phophofructokinase?
AMP
Fructose-2,6-Bisphosphate
How does insulin activate PFK1?
It activates it using a mediator called Fructose-2,6-bisphosphate
How does insulin activate PFK1 in more detail?
Insulin binds to the recptor on hepatocytes
Insulin activates PFK-2
PFK-2 converts a tiny amount of fructose-6-phosphate to fructose-2,6-bisphosphate
Fructose-2,6-phosphate will activate PFK-1
PFK-1 will turn Fructose-6-phosphate into fructose-1,6-bisphosphate
What reaction requires NAD+
Rxn 6
What is the enzyme used in Rxn 6?
Glyceraldehyde 3-phosphate dehydrogenase
What is the product of Rxn 6?
1,3-Bisphosphoglycerate
(Remember 2,3-BPG )
Remember the 6 hemoglobin molecules in oxy affinity lec
What happens in Rxn 7?
1,3-Bisphosphoglycerate Breaks down into 3-Phosphoglycerate to produce 2 ATP (bc it is 2 reactions)
(Substrate level phosphorylation)
What is special about Rxn 9?
The enzyme that catalyzez Rxn 9 is Enolase.
Enolase is inhibted by fluoride.
Enolase is used by bacteria to form tooth decay.
What happens in Rxn 10?
It is catalyzed by Pyurvate Kinase
It is the second Substrate level phosphorylation reaction (2 ATP is produced)
Third regulated step.
Activated by fructose 1,6-bisphosphate (feed forward activation)
What happens to the RBCs bc of pyruvate kinase deficeny? Are there heinz bodies?
Decreased ATP production which leads to the inability of the cell to maintain the ion pumps
This inturn leads to the inability of the cell to sustain its membrane
Causing the cells to swell and burst.
No heinz bodies present
What happens to 2,3-Bisphosphoglycerate bc of pyruvate kinase deficeny?
The reaction will go backward bc of the fact that Pyruvate kinase is deficent.
This will convert Phosphophenolpyruvate back into 1,3-bisphosphateglycerate which will then be converted to 2,3-BPG.
This causes an increase in 2,3-BPG in the body which will decrease the hemoglobin’s affinity to oxygen.
What are the 3 hormonal regulated reactions? What hormones regulate them?
Rxn 1,3,10.
Which enzymes are regulated by phosphorylation?
PFK-2
and
Pyruvate kinase
Does glycolsis require oxygen?
NO
What are the two fates of pyruvate?
Either it will be converted into acytl COA into the electron transport chain (in cells with mitochondria and enough oxygen)
- Pyruvate will be converted into Lactate or ethanol (without oxygen/mitochondria) (fermentation)
What are some situations where the body switches to anaerboic glycolsis?
Rigorus exercise in muscle cells (produces lactic acid)
High altitude
Ischemic cells (to prevent cell death)
