Introduction of glucose metabolism lecture 4
This presentation is the property of its rightful owner.
Sponsored Links
1 / 8

Introduction of Glucose Metabolism Lecture-4 PowerPoint PPT Presentation


  • 48 Views
  • Uploaded on
  • Presentation posted in: General

Introduction of Glucose Metabolism Lecture-4. GLUCONEOGENESIS. GLUCONEOGENESIS. Gluconeogenesis is the synthesis of glucose from glucogenic precursors which are not of carbohydrate origin ( gluconeogenic precursors) It occurs during prolonged fasting to synthesize glucose for tissues

Download Presentation

Introduction of Glucose Metabolism Lecture-4

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Introduction of glucose metabolism lecture 4

Introduction of Glucose Metabolism

Lecture-4

GLUCONEOGENESIS


Gluconeogenesis

GLUCONEOGENESIS

Gluconeogenesis is the synthesis of glucose from glucogenic precursors

which are not of carbohydrate origin (gluconeogenic precursors)

It occurs during prolonged fasting to synthesize glucose for tissues

requiring continuous supply of glucose as a source of energy:

Brain, RBCs, Kidney medulla, Lens, Cornea, Testes, sk.ms

Gluconeogenesis occurs ONLY in the liver & kidneys


Gluconeogenic precursors

Gluconeogenic precursors

1- Intermediates of glycolysis

by reverse of steps of glycolysis (except 4 steps that need 4 different enzymes)

2- Intermediates of citric acid cycle

are converted to oxalacetate then to glucose

3- Lactate

Lactic acid formed of anaerobic glycolysis in cells as RBCs & skeletal muscles

are transported in blood to liver to be converted to pyruvate then to glucose (Cori cycle)

4- Glycerol

Glycerol is derived from the lipid triacylglycerol in adipose tissue.

Glycerol is converted into dihydroxyactone phosphate (intermediate of

glycolysis) then to glucose.

5- Glucogenicamino acids of proteins

Glucogenic amino acids are deaminated to form a-ketoacids

a-keto acids are converted to pyruvate or intermediates of citric acid cycle then to glucose


Introduction of glucose metabolism lecture 4

GLUCOSE

Triacylglycerol

in adipose tissue

Precursors

of

Gluconeogenesis

Fatty acids

Gluconeogenesis

Glycerol

Lactate

Oxalacetate

Pyruvate

Intermediate of

CITRIC ACID CYCLE

Glucogenic amino acids

in proteins as sk. ms.


Glycerol as a gluconeogenic substrate

Glycerol as agluconeogenic Substrate

Glycerol

Kinase

Glycerol

Glycerol 3-phosphate

ATP

ADP

NAD+

Glycerol 3-phosphate

dehydrogenase

NADH

Glucose

Dihydroxyacetone phosphate

GK: Glycerol kinase only in liver & kidneys


Glucogenic amino acids

GlucogenicAmino Acids

Glycine, Alanine

Amino

acids

Pyruvate

Aspartate

Aspargine

Glutamate Glutamine

Amino

acids

Phenylalanin

Tyrosine

Methionine

Valine


Introduction of glucose metabolism lecture 4

Cori Cycle

Lactate

is a gluconeogenic precursor


Introduction of glucose metabolism lecture 4

Unique enzymes of gluconeogenesis

Reactions 1, 2, 3 & 4

are catalyzed by enzymes

NOT used in glycolysis

GLUCOSE

1- Pyruvate to oxalacatate

by pyruvatecarboxylase

2- oxalacetate to phosphoenolpyruvate

by PEP carboxykinase

3- Fructose 1,6 bisphosphate to fructose 6 phosphate

by fructose 1,6 bisphosphatase

4- Glucose 6-phosphate to glucose

by glucose 6-phosphatase

GLUCONEOGENESIS

Other reactions of gluconeogenesis are catalyzed

by same enzymes of glycolysis in the reverse direction


  • Login