IT IS RELATED WITH CARBOHYDRATE METABOLISM

1. FORMATION AND FATE OF
GLUCOSE 6 PHOSPHATE
SECOND YEAR MBBS
DR SADIA HAROON
1.7.2021

3. Pathways
1. Anabolic Pathways
– Synthesis of larger molecules from smaller molecules
– Endothermic (energy requiring) processes
e.g. gluconeogenesis, protein synthesis
2. Catabolic Pathways
– Breakdown of larger molecules (oxidative)
– Exothermic (energy yielding) processes e.g. Glycolysis
3. Amphibolic Pathways
Involved in synthesis as well as breakdown of molecules
– Act as link between anabolic & catabolic pathways e.g.
Citric acid cycle

5. Carbohydrate Metabolism
Revolves around the provision and fate of glucose
– Glycolysis
– Hexose mono-phosphate shunt
– Uronic acid pathway
– Gluconeogenesis
– Glycogenesis
– Glycogenolysis
– Citric acid cycle (common metabolic pathway) 5

6. BIOMEDICAL IMPORTANCE OF GLUCOSE
• Provide ATP energy
• Generate intermediates for other pathways
• Hexose monophosphate pathway
• Glycogen synthesis
• Pyruvate dehydrogenase
• Fatty acid synthesis
• Krebs’ Cycle
• Glycerol-phosphate (TG synthesis)
6

7. Glycolysis:
Specific tissue functions
• RBC’s
– Rely exclusively for energy
• Skeletal muscle
– Source of energy during exercise, particularly high intensity
exercise
• Adipose tissue
– Source of glycerol-P for TG synthesis
– Source of acetyl-CoA for FA synthesis
• Liver
– Source of acetyl-CoA for FA synthesis
– Source of glycerol-P for TG synthesis

8. Gluconeogenesis
Uronic Acid Pathway
Glycogenesis
glycogenolysis
Glc     CO2 + H2O
30 steps of controlled burning of Glc
Energy
Provision

9. Central Role of Glucose

10. Where do the intermediates in glycolysis go?
• G-6-P goes off to make the ribose for nucleotides
• F-6-P -amino sugars-glycolipids and glycoproteins
• G-3-P/DHAP-lipids
• 3PG-serine
• PEP-aromatic amino acids, pyrimidines, asp and asn
• Pyruvate-alanine
This pathway not only important in glucose metabolism--generates
intermediates for other important building blocks
G-6-P = glucose 6 phosphate, F-6-P = fructose 6 phosphate, G-3-P = glyceraldehyde 3 phosphate, DHAP =
dihydryoxacetonephosphate, 3PG = phosphoglyceraldehyde, Pyr = pyruvate

11. Significance / Importance
• Glycolysis is required by all cells & tissues
substantially for brain and totally for RBCs
• Major pathway for glucose utilization
• Fructose and Galactose are also metabolized through
this pathway
• Can provide energy (ATP) even in absence of oxygen
• Provides carbon skeleton for the synthesis of
non-essential amino acids
• Provides glycerol for the synthesis of fats

12. Biological importance (functions) of glycolysis:
1. Energy production:
a) anaerobic glycolysis gives 2 ATP.
b) aerobic glycolysis gives 8 ATP.
2. Oxygenation of tissues:
Through formation of 2,3 bisphosphoglycerate, which decreases the
affinity of Hemoglobin to O2.
3. Provides important intermediates:
a) Dihydroxyacetone phosphate: can give glycerol-3phosphate, which is
used for synthesis of triacylglycerols and phospholipids (lipogenesis).
b) 3 Phosphoglycerate: which can be used for synthesis of amino acid
serine.
c) Pyruvate: which can be used in synthesis of amino acid alanine.
4. Aerobic glycolysis provides the mitochondria with pyruvate, which gives
acetyl CoA Krebs' cycle.

13. Overview of the major
pathways of glucose
metabolism

14. Transketolase
requires
thiamine
pyrophospate
(TPP) as a
coenzyme
NADPH is
necessary to
protect against
reactive oxygen
species
Ribose 5-P is
necessary in rapidly
dividing cells

15. Transketola
se requires
thiamine
pyrophospat
e (TPP) as
a coenzyme
NADPH is
necessary to
protect against
reactive oxygen
species
Ribose 5-P is
necessary in rapidly
dividing cells

18. DISORDER OF GALACTOSE METABOLISM
In lactating
mammary
gland
in liver
Enters
glycolysis
If Gal in diet is
insufficient
in
liver

19. METABOLISM

20. SUMMARY
Glucose
Glucose 6-P
Fructose 6-P
Fructose 1,6-bisphosphate
Dihydroxyacetone
phosphate
Glyceraldehyde 3-P
Fructose
Fructose 1-P
Galactose
Galactose 1-P
Glucose 1-P
Mannose
Mannose 6-P
Glyceraldehyde
glycolysis