بسم اهلل الرمحن الرحيمThis seminar is presented by

حييى امحد مشس الدين خروفة

حييى اخلالدي عمر راكان

GLUCOSE

Between USE

& STORAGE

GLYCOLYSIS

Reaction #1 Phosphorylation of glucose

Reaction #1 Phosphorylation of glucose

Reaction #2 Isomerization of glucose 6-

phosphate

Regulation of glucokinase

Reaction #3 Phosphorylation of fructose

6-phosphate

Regulation of PFK

Reaction #4 Cleavage of fructose 1,6-

bisphosphate

Reaction #5 Isomerization of

dihydroxyacetone phosphate

Reaction #6 Oxidation of glyceraldehyde

3-phosphate

Reaction #7 Synthesis of 3-

phosphoglycerate

Reaction #8 + Reaction #9 + Reaction #10

Regulation of pyruvate kinase

HORMONAL REGULATION OF

GLYCOLYSIS

Gluconeogenesis

Gluoconeogenesis

• Is the formation of glucose from non-

carbohydrate sources e.g lactic acid ,amino

acids , glycerols and propionate.

• Site: liver and kidney.

Cont.

• Liver and kidney contains all enzymes of

glconeogenesis.

• It does not occur in skeletal muscles due to

deficiency of glucose -6-p

• It does not occur in heart muscle,smooth

musacles, and dipose tissues due to

deficiency of fructose 1-6 dip.

Importance

• Glucose is the only source of energy:

• 1. nervous system

• 2.Skeletal system

• Glucose is required :

• 1. Adipose tissues: as a source of glycerol

• 2.Mammary gland:as a source of lacotse

gluco neo genesis

sugar (re)new make/ create

glycolysis

glucose

pyruvate lactate

gluconeogenesis

Topics: Gluconeogenesis

1. Principles, substrates & relationship to glycolysis

2. Bypass of irreversible steps in glycolysis

3. Link between liver gluconeogenesis and muscle/RBC/brain glycolysis; the Cori and Alanine cycles

Gluconeogenesis

• Occurs in all animals, plants, fungi and microbes

• Occurs largely in the liver; some in renal cortex

• Of 10 enzymatic steps, 7 are reversals of glycolytic reactions

Carbohydrate synthesis

from simple precursors

Metabolites feed into

gluconeogenesis at various points

main path

All AA can feed into

gluconeogenesis except leucine

and lysine

Bypass of irreversible steps in glycolysis

Dephosphorylation of G6P, 3rd bypass reaction

Glucose 6-phosphatase removes the phosphate to liberate free glucose

• This is primarily a function of the liver to buffer blood glucose levels

• G6Pase is NOT present in brain and muscle! (Gluconeogenesis does not occur in these tissues)

glucose-6-P + H2O glucose + Pi

G6Pase

Note that both Glycolysis and Gluconeogenesis are energetically

favorable under physiological conditions and therefore both ~ irreversible

processes

Glycolysis DG[phys] = -63 kJ/mol Gluconeogenesis DG[phys] = -16 kJ/mol

Significance

Remove lactate in muscle

Increase blood sugar level using amino acids(alanine) in special situation

You should know: 1. Chemical steps of GN; associate enzymes

2. Requirement for mito shuttle system

3. Precursors that can enter GN;

4. Relationship of GL to GN; shared enzymes, irreversible steps

5. Liver as the primary GN organ; Cori Cycle, Alanine Cycle

Le Fin