Carbohydrate $ Its Metabolism

8/6/2019 Carbohydrate $ Its Metabolism

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Neha Sharan

M.Sc. Biotech

2ndsem.


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Most abundant organic moleculein nature.

Empirical formula is cn(H O)n.Carbohydrates are sugar.

Defined as hydrate of carbon.

Structurally it is viewed byPolyhydroxy aldehyde $Polyhydroxy ketone.

2


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Most important source of energy.

Present in both animals $ plants.

In plant carbohydrate are present inits skeleton.

In animal carbohydrate are found inliver $ muscle cells.

Carbohydrate are simple $ complex

depending on their structure.


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Simple

carbohydrates aresugar which foundnaturally in foodsuch as fruits,vegetables, milk$ milk products.

Complex

carbohydrateinclude grain,breads,cereals,$

legumes.


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Carbohydrate are of 3 types-

1.Monosaccharide

2.Oligosaccharide

3.Polysaccharide

MONOSACCHARIDE-

Simplest group of carbohydrate. Reffered to as simple sugar.


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Monosaccharide can not be hydrolyse.Divided in to different category-

Based on functional group-

Aldoses- e.g.Glyceraldehyde.

Ketoses- e.g.Fructose. Based on no. of carbon atom-

Trioses

Tetroses

Pentoses

Hexoses


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OLIGOSACCHARIDE-2-10 no. of carbon combine to form

oligosaccharide.Among oligosaccharides, disaccharides

are the most common.Disaccharide consists of two

monosaccharide units held together bya glycosidic bond.These are crystaline, water soluble,$

sweet to taste.Disaccharide are of two type- Reducing- Disaccharide with free

aldehyde $ ketone group.e.g-maltose, lactose.


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Non reducing- Disaccharide with no freealdehyde or keto group.

e.g-sucrose .POLYSACCHARIDE-

Glycans

It consists of repeating unit of

monosaccharides. These are higher molecular weight

carbohydrate.

Polysaccharide are off two types-

Homopolysaccharide- On hydrolysis it yieldsonly a single type of monosaccharide.

Hetropolysaccharide- On hydrolysis it gives

a mixture of monosaccharide.


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Takes place in all cell of the body.

Occurs in the anaerobic condition $aerobic condition both.

End product of anaerobic condition islactate.

The end product of aerobic condition ispyruvate.

Here we see aerobic conditionGlycolysis are in two phase-

Preparative phase

Pay off phase


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The 2 mole of ATP are used in preparativephase in step 1st $ 3rd .

There are 4 mole of ATP are formed during

glycolysis in pay off phase in step 7th $10th.

Total no. of ATP = 4 ATP

Net gain ATP-2 ATP


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Step 1st -Phosphorylation

Step 2nd Isomerisation

Step 3rd Phosphorylation

Step 4th Cleavage

Step 5th Phosphorylation $Dehydrogenation

Step 6

th

ATP generation Step 7th Isomerisation

Step 8th Dehydration

Step 9th ATP generation


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Kreb cycle was proposed by Hans aldofkreb in 1937.

Kreb cycle is the most important metabolic

pathway for the energy supply to the body.About 65-70% of the ATP is synthesized in

kreb cycle.

Kreb cycle essential involved the oxidation

of acetyl coA to CO $ H O.2 2


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The synthesis of glucose from non-carbohydrate compounds is known asgluconeogenesis.

Occur mainly in the cytosol.The major substrate/precursors for

gluconeogenesis are lactate, pyruvate,glucogenic amino acids, propionate $

glycerol.Mostly takes place in liver, kidney matrix.

Gluconeogenesis occurs in 3 steps-


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1. Irreversible

2. Reversible

3. Dephosphorylation


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Also called hexose mono phosphate or HMPshunt.

This is an alternative pathway of glycolysis.

However HMP is more anabolic in nature,since it concerned with the biosynthesis ofNADPH $ pentoses.

The pathway starts with glucose 6

phosphate.No ATP is directly utilized or produce in

HMP pathway.

It is a unique multifunctional pathway.


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The enzymes of HMP are locate in the

cytosol.The tissues such as liver, adipose tissue,

adrenal gland, testes,$ lactating mammarygland are highly active in HMP

Most of these tissues are involved in thebiosynthesis of fatty acids $ steriods whichare dependent on the supply of NADPH.

HMP is divided in to two phases-

1. Oxidative phase2. Non oxidative phase


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Carbohydrate $ Its Metabolism

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