carbohydrates-definition-nomenclature-classification-mono-oligo(di-tri-tetra)-poly saccharides general inforation by study everything

 

 

CARBOHYDRATES(basics)

 

“Carbohydrates is the optically active polyhydroxy aldehydes or polyhydroxy ketones.”

Or

“carbohydrates are the substance which reaction of hydrolysis or condensation reaction gives  polyhydroxy aldehyde or ketone” .

 

What do you mean of polyhydroxy aldehyde and ketone ?

 Poly means : several or many .

Hydroxy means : -OH group .

Aldehyde means : an organic compound which have [–CHO] group in their structure.

Ketone means : an organic compound which have a [–C=O-] group in their structure .

 

Carbohydrates mainly contains carbon(C) hydrogen (H) and oxygen (O) elements in their structure.

when we heat the sugars or carbohydrates for long time we get the black residue of carbon and droplets of water that is way carbohydrates are called hydrates of carbon .

generally the animals  body can not make a carbohydrates or animal are incapable for the synthesis of carbohydrates ,therefore they are dependent upon the plants .plants are vital source of carbohydrates ,commonly we can obtain carbohydrates from plants , carbohydrates plays important role in human they can provide our primary requirements like food , clothing , fuel , and shelter.

Earliest researches shows that the ratio of hydrogen (H) and oxygen (O) elements in carbohydrates is a 2:1 same as a water .(ratio of hydrogen and oxygen element in water (H₂O) is 2:1).

Fore example :

1)      Sucrose

Molecular formula : C₁₂H₂₂O₁₁ or C₁₂(H₂O)₁₁ .

number of elements in sucrose (note : here  we have include only hydrogen and oxygen for ours understanding )

hydrogen :22                                 oxygen : 11

ratio : 22:11  = 2:1

 

2)      Glucose :

Molecular formula : C₆H₁₂O₆  or C₆(H₂O)₆

Number of elements in glucose ; (note : here we have include only hydrogen and oxygen for ours understanding )

Hydrogen : 12                         oxygen : 6

Ratio : 12:6

             =2:1

 

3)      Starch

Molecular formula : [C₆H₁₀O₅]_n or [C₆(H₂O)₅]_n

number of element in starch   (note : here we have include only hydrogen and oxygen for ours understanding )

 

hydrogen : 10                 oxygen : 5

ratio : 10:5

          = 2:1

 

Common formula of carbohydrates is C_p(H_2­O)_Q (Note : these is not exact or real formula of carbohydrates .  “ How” ?   please take a look on next paragraph .)

Here , p will be number of carbon

And  , Q  will be number of water  (H_2­O) molecule .

Some of the carbohydrates not have a 2:1 ratio of hydrogen and oxygen element in their structure for example : rhamnose (C₆H₁₂O₅) and also some of the compounds are not carbohydrates but they have a 2:1 ratio of hydrogen and oxygen element in their structure .for example : acetic acid (C₂H₄O₂) or (C₂(H₂O)₂ and formaldehyde : (CH₂O) .so the 2:1 ratio of hydrogen and oxygen is not applicable for all carbohydrates that is way the common formula C_p(H_2­O)_Q is not exact or real for all carbohydrates .

Rhamnose (C₆H₁₂O₅): (carbohydrate but not contains 2:1 ratio of hydrogen and oxygen element.)

Number of element in rhamnose (note : here we have include only hydrogen and oxygen for ours understanding )

 

Hydrogen : 12                              oxygen : 5

ratio 12:5

ratios is ≠ 2:1 (not 2:1)

acetic acid (C₂H₄O₂) or C₂(H₂O)₂ : (it is not carbohydrate but contains 2:1 ratio of hydrogen and oxygen ).

Number of element in acetic acid (note : here we have include only hydrogen and oxygen for ours understanding )

Hydrogen :4                            oxygen : 2

Ratio is 4:2

Ratio is = 2:1

Formaldehyde (CH₂O) : (it is not carbohydrate but contains 2:1 ratio of hydrogen and oxygen ).

Number of element in formaldehyde (note : here we have include only hydrogen and oxygen for ours understanding )

Hydrogen :2                         oxygen : 1

Ratio is 2:1

Ratio is = 2:1

Carbohydrates are some times called saccharides because of the sweet taste of simple member of carbohydrates , such as sugar (sugar means : in latin sugar means seccharum and in greek sugar means seccharon) .

The carbohydrates which have low molecular weight are known as sugars or saccharides eg. Sucrose , glucose , fructose.

And other carbohydrates which have a high molecular weight are known as non-sugars eg. Starch , cellulose .

Nomenclature of carbohydrates :

1.       Generally “ose” suffix is used for giving name of carbohydrates or sugars for example , glucose , fructose , maltose , lactose , sucrose , rhamnose , raffinose etc.

 

2.       The another portion of name will given on the bases of origin and history of particular substance .for example lactose (lactose means milk - in latin word lactis means milk).

 

3.       Carbohydrates which contains aldehyde group in their structure known as aldose, for example glucose is aldose sugar.

 

4.       Carbohydrates which contains keto group in their structure known as ketose , for example fructose is ketose sugar.

 

5.       Tri ,Tetra , penta , hexa……… [(greek words ) (in English word three , four , five , six……)  is the term used in front of the Ose suffix to denote the number of carbon atoms in carbohydrate compounds.

Eg. Four carbon + aldehyde group = aldotetrose.

       Four carbon + keto group     = ketotetrose.

In detail we can take example of glucose , so the glucose is the aldohexose sugar.

 

Structure of glucose :

 

6.       As we know the carbohydrates have a cyclic structure so name of cyclic carbohydrates is given below .

The cyclic compound with five members(four carbon +one oxygen) is represented by the word furan.

Structure of furan ring :

 

Eg. Fructose (fructofuranose).

 

The cyclic compound with six members(five carbon + one oxygen) is represented by the word pyran.

Structure of pyran ring :

 

Eg. Glucose (glucopyranose) .

Classification of carbohydrates :

 

 

On the basis of hydrolysis carbohydrates are classified in to three types 1. Mono-saccharides , 2. Oligo-saccharides , and poly-saccharides .

1 . mono-saccharides :

“that types of carbohydrates which is further not divided  into more smaller unit , known as mono-saccharides”.These is the simplest carbohydrates , it includes three , four , five, six……..ten , members carbohydrates , common formula of mono-saccharides is C_sH_2sO_s .

Here, s =number of carbon atom.

 

Example :  glucose(C₆H₁₂O₆) , fructose(C₆H₁₂O₆).

 

2 . oligo-saccharides : (greek word oligo means few)

“that types of carbohydrates which hydrolyzed into tow or more mono-saccharides known as oligo-saccharides”.

Oligo-saccharides are contains two to four mono-saccharide units .oligo-saccharides are divided into more three groups , di-saccharides ,tri-saccharides , tetra-saccharides .

[a] di-saccharides :

the hydrolysis of carbohydrates give two mono-saccharide which is known as disaccharides . common formula of disaccharides is C_sH_2s-2O_{s-1. .} Generally soluble in water and sweet in taste .

Here , s = number of carbon atom .

 

Eg. Maltose [C₁₂H₂₂O₁₁] _, sucrose [C₁₂H₂₂O₁₁] , lactose [C₁₂H₂₂O₁₁] , cellobiose[ C₁₂H₂₂O₁₁].

 

[b] tri-saccharides :

the hydrolysis of carbohydrates give three mono-saccharide which is known as tri-saccharides . common formula of tri-saccharides is C_sH_2s-4O_{s-2. .} Generally soluble in water and sweet in taste .

Here , s = number of carbon atom .

 

Eg. Maliose or raffinose [C₁₈H₃₂O₁₆]

[c] tetra-saccharides :

the hydrolysis of carbohydrates will give four mono-saccharide which is known as tetra-saccharides . common formula of tetra-saccharides is C_sH_2s-6O_s-3. Generally soluble in water and sweet in taste .

Here , s = number of carbon atom .

 

Eg. Stachyose [C₂₄H₄₂O₂₁]

 

3 . poly-saccharides (non-sugars):

the hydrolysis of carbohydrates will give many molecules of mono-saccharide which is known as poly-saccharides . poly-saccharides is non sugary or not sweet in taste that is way it’s also known as non-sugars .poly-saccharides are insoluble in water because of their higher molecular weight.

 

eg. Cellulose or starch (C₆H₁₀O₅)_{n ,} glycogen , etc.                   

 

 

 

 

 

 

 

 

 

 

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