Sources of Gluconeogenesis Precursors
Glycogen branching cartoon
In exercising muscle, ____ also helps to activate phosphorylase kinase.
In exercising muscle, the elevated calcium (released to promote contraction) also helps to activate phosphorylase kinase.
Hepatomegaly usually indicates. . .
. . .defects in liver carbohydrate metabolism.
Regulation of glycogen phosphorylase
NAD+ and NADP+
Ketogenic-only amino acids
Leucine and Lysine. Thus they cannot be used to generate glucose.
Key Gluconeogenesis Steps
Why is glycogen stored as a polymer?
The high concentration of glucose 6-phosphate would create a strong osmotic load on the cell, causing water to enter and swell the cell, causing it to lyse
Glycogen molecular structure
Glycogen branching enzyme creates ____ linkages.
Glycogen branching enzyme creates α1→6 linkages.
Ratios of NAD+ to NADH and NADP+ to NADPH.
Akt in glycogen synthesis
Akt will also help stimulate glucose transport (Glut4)
Role of α1→6 glucosidases in glycogenolysis
α1→6 glucosidases remove the terminal α1→6 -bound glucose in a glycogen branch, leaving a linear chain.
Glycogenolysis and gluconeogenesis have the same _____.
Glycogenolysis and gluconeogenesis have the same terminal step.
This step is dephosphorylation by glucose-6-phosphatase, which produces free glucose that may be exported into the bloodstream.
UDP glucose synthesis
Glycogen synthase regulation
Akt is what phosphorylates GSK3, turning it off.
In order for glycogen synthase to add a glucose, the existing glycogen molecule must be ____.
In order for glycogen synthase to add a glucose, the existing glycogen molecule must be at least 4 glucose units long.
Thus the only storage forms of glucose in the body are. . .
1. Glycogen, which is used quickly
2. Amino acids, stored in muscle, which must be converted into glucose via gluconeogenesis
3. Glycerol, which is stored in triglycerides
What level of Acetyl-CoA would favor gluconeogenesis in the liver?
High acetyl CoA inhibits pyruvate dehydrogenase and activates pyruvate carboxylase, stimulating conversion of pyruvate to oxaloacetic acid.
Liver glycolysis vs gluconeogenesis diagram
When the body is fasting for prolonged periods, fats provide the major energy source for the body, but do not directly provide _____
When the body is fasting for prolonged periods, fats provide the major energy source for the body, but do not directly provide the carbon skeletons.
These are provided by amino acids.
Located in mitochondria
Where is PEP Carboxykinase located?
Where is pyruvate carboxylase located?
Pentose Phosphate Pathway from 10,000 ft