2. Gluconeogenesis
Gluconeogenesis is the process whereby precursors
such as lactate, pyruvate, glycerol, and amino acids
are converted to glucose.
Fasting requires all the glucose to be synthesized
from these non-carbohydrate precursors.
Most precursors must enter the Krebs cycle at some
point to be converted to oxaloacetate.
Oxaloacetate is the starting material for
gluconeogenesis
5. Malate Shuttle
OAA (oxalacetic acid)
produced in mitochondria
mitochondrial membrane
impermeable to OAA
malate transporter in mito.
Membrane
malate dehydrogenase in
both mito and cyto
NADH produced in cyto
also used in
gluconeogenesis.
9. Precursers for gluconeogenesis
figure 13-4
Alanine and other amino acids
transamination of pyruvate
pyruvate derived from glycolysis or from amino acid degradation
alanine cycle
10. Coordinated Regulation of
Gluconeogenesis and Glycolysis
Regulation of enzyme
quantity
Fasting: glucagon, cortisol
induces gluconeogenic enzymes
represses glycolytic enzymes
liver making glucose
Feeding: insulin
induces glycolytic enzymes
represses gluconeogenic
enzymes
liver using glucose
11.
12. BIOCHEMICAL
MESSENGERS
There are 5 types
Cholinergenic(acetycholine),Aminoacid(Gl
utamicacid),Adrenergic(adrenaline)Peptide
rgenic(Insulin,Glucagon,Enkephalin) &
Steroids(cortisol)
First three types are known as
neurotransmitter while last three are
known as Hormones
13. Regulation of glycogenolysis in the liver
by glucagon:
cAMP → protein kinase A:
1. inactivates glycogen synthase
2. activates glycogen phosphorylase
