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Carbohydrate Biosynthesis

Gluconeogenesis

Principle of Metabolic Regulation: Glucose and Glycogen

Carbohydrate Biosynthesis in Plant

Can you tell me :

Why do we need glucose in our body?

need glucose?In which kind of situation do we

(^) Normal physiology situation:

-Exercise/work-Between meals and during sleep

(^) After heavy exercise or work (recycling of lactate)

(^) After protein-rich diet (glucogenic amino acids)

(^) Starvation (glucogenic amino acids)

4. Photosynthetic carbohydrate3. Analysis of metabolic control2. Biosynthesis of glycogen1. Gluconeogenesis

synthesis (the Calvin Cycle);

5. Regulation of carbohydrate

metabolism in plants.

6. Biosynthesis of starch and sucrose

Contents

Overview of Glucose Metabolism

Glucose-6-phosphate

Glucose

Glycogen

Pyruvate

Lactate

Amino acids

Acetyl-CoA

Ribose-5-phosphate

irreversible

1. Gluconeogenesis

(“formation of new sugar”)

precursorsthe formation of glucose from non-carbohydrate

to 96% of total glucose production.In fasting conditions: gluconeogenesis accounts for up160g (120g for brain), glycogen can provide 190g.Daily glucose requirement (human being):small amount in kidneyOrgans (in higher animals): occurring largely in liver, aSpecies: all animals, plants, fungi and microorganisms

1

. Gluconeogenesis refers to the metabolic pathway

that results in net glucose production:

5. from alanine4) from starch3) from glycogen2) from pentose phosphates1) from fructose and galactose

2. The gluconeogenetic pathway is active:

1. in liver cells, when on a low carbohydrate diet

2. in kidney medulla when circulating [Glc] is low4) in adipocytes during fasting3) in heart cells during starvation2) in muscle cells during intense exercise

for net glucose biosynthesis because:It is said that animal cells cannot use fat

1) No part whatsoever of a triacylglyceride

molecule can be converted into Glc

2) No part of any fatty acid whatsoever can be

made into Glc

3) Acetyl CoA is completely degraded into CO

and water in the TCA cycle

4) Any substrate that replenishes the TCA cycle

is completely degraded to CO

2

gluconeogenesis

glucose

glucogneonesisstarting material for Oxaloacetate is the

gluconeogenesisWhat is role of

in plant?

in germinating seedsfatty acids to sucroseConversion of stored

Glyoxysome

Mitochondrion

Cytosol

from stored lipids.production of sucroserequired for thecompartments isthree subcellularreaction sequences inThe integration of

Gluconeogenesis is not a reversal of

glycolysis

3 Irreversible steps in glycolytic pathway

Glucose + ATP

(^) Glucose 6-phosphate + ADP

 G = -8.0 kcal mol

(-33 kJ mol^

)

Fructose 6-phosphate + ATP

 Fructose 1,6-bisphosphate + ADP G = -5.3 kcal mol

(-22 kJ mol^

)

Phosphoenolpyruvate + ADP

^ Pyruvate + ATP G = -4.0 kcal mol

(-17 kJ mol^

)

Hexokinase

Pyruvate kinase Phosphofructokinase

A. Conversion of pyruvate to phosphoenolpyruvate

(two exergonic reactions)

Pyruvate + ATP + GTP + H

2 O (^) 

phosphoenolpyruvate + ADP + GDP + Pi + 2H

Mitochondrial enzyme

Mitochondrial enzyme/cytosolic enzyme

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