'' Biomolecules Class 12th chemistry notes|NCERT Based|Exam revision''

CLASS 12TH – BIOMOLECULES NOTES
INCLUDING PYQ OF 2026
HIGH SCORING AND EASY TO UNDERSTAND
 These are complex lifeless chemical substance.
 Not only build up living system.
 But also responsible for growth , maintainence , and their ability to
reproduce
Ex. Carbohydrate , protein, vitamin , nucleic acid , etc.


CARBOHYDRATE
 These are natural occurring organic compound.
 It is saccharide i.e. sugar forming.
 In plants , these are produce by photosynthesis.


 New definition
These are optically polyhydroxy aldehyde or ketone i.e. contain
more no. of OH group which are optical compound .
Compounds which produce such units are also known as
carbohydrates.
Classification of carbohydrates
I. On the basis of size
a. Monosaccharide - Simplest carbohydrate which can not be
hydrolysed into smaller parts

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, Ex. Glucose , Fructose , Ribose, etc.
b. Oligosaccharide - On hydrolysis produce 2 – 10 molecules of
monosaccharide .
Ex. Sucrose , Maltose , Lactose , etc.
C. Polysaccharide – On hydrolysis produce large number of
monosaccharide .
Ex . Starch , Cellulose , Glycogen , etc .
II. On the basis of taste
i. Sugar carbohydrate - Have sweet taste .
Ex. Monosaccharide , Oligosaccharide.
ii. Non sugar carbohydrate – Note have sweet taste.
Ex. Polysaccharide.
III. On the basis of nature
1) Reducing sugar
 They reduce tollens reagent and fehling solution.
 Their reducing centre are free.
 All monosaccharide and oligosaccharide are reducing sugar
except sucrose.
2) Non reducing sugar
 They not reduce toolens reagent reagent and fehling solution.
 Their reducing centre are not free.
 All polysaccharide and one disaccharide sucrose are non
reducing sugar.


MONOSACCHARIDE


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, GLUCOSE C6H12O6
 It is most abudent natural occurring organic compound.
 It is present in sweet fruits and honey.
 It is present in free state as well as in combine state.

 PREPRATION
From sucrose- C12H22O11  H2O H C6H12O6  C6H12O6
Sucrose Glucose Fructose
Glucose and fructose have same formula but they have
different structure .
From starch - C6H10O5n H nC6H12O6
Starch Glucose
 STRUCTURE
 Aldehexoses  one aldehyde and six carbon  .
 As aldehyde is monovalent . So, present at the end of the
chain.
 It is dextrorotary .


 OPEN CHAIN STRUCTURE - CHO
CHOH4
CH 2OH

 EVIDENCE OF OPEN CHAIN STRUCTURE


CHO
CHOH4 HI/Red P CH3 CH24 CH3


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