CARBOHYDRATES

By: Dr. MohammedAzim Bagban MI 201 Assistant Professor, Unit-1 C. U. SHAH Institute of Science LECTURE OUTLINE

 The Importance of carbohydrates.

 The Definition of Carbohydrates.

 The Classification of Carbohydrates.

 The Difference between various Isomers..

CARBOHYDRATE: IMPORTANCE

 Most Abundant Class of Biomolecules.

 An Important Macronutrient.

 Performs important physiological functions in the body.

 Associated with Pathological Conditions (Diabetes Mellitus, Lactose Intolerance).

DEFINING CARBOHYDRATES

Carbohydrates or Saccharides (Greek Sakcharon meaning "Sugar")

 Organic compounds composed of Carbon, Hydrogen and oxygen.

 Many Carbohydrates also contain Nitrogen and other elements. Carbohydrates derive their name from a Misleading Concept 'Hydrates of Carbon’  Hydrogen and Oxygen in Carbohydrates were found to be present in the same proportion as in water. (2:1).(E.g. Glucose C6H12O6 or C6 (H2O)6).

 It is due to this fact that compounds derived their name “Carbon Hydrate”.

GLUCOSE

H-C=O  H-C-OH  OH-C-H  H-C-OH  H-C-OH 

CH2OH This term is not a perfect derivation as many carbohydrates do not have the same proportion as water.

Example: DEOXYRIBOSE (C5H10O4) H-C=O  H-C-H  H-C-OH  H-C-OH 

CH2OH

CHEMICAL DEFINITION OF CARBOHYDRATES

 Polyhydroxyl: Having more than one hydroxyl group. (-OH)

 Functional Group: It is a specific group of atoms or bonds which are part of a larger hydrocarbon chain.(Provide a specific chemical behaviour).

 For carbohydrates, the functional group is the carbonyl group which may be either

Aldehyde Group (C-H-O) Or Keto Group (C=O) WHAT IS SIMILAR & DIFFERENT IN THESE TWO STRUCTURES? CHO CH2OH   H-C-OH C=O More than  one hydroxyl  group in both OH - C-H OH-C-H   H-C-OH H-C-OH   CH2OH CH2OH WHAT IS COMMON & DIFFERENT IN THESE TWO STRUCTURES? H-C=O CH2OH   H-C-OH C=O Carbonyl  Group in  both But? OH - C-H OH-C-H   H-C-OH H-C-OH   CH2OH CH2OH WHAT IS COMMON & DIFFERENT IN THESE TWO STRUCTURES? H-C=O CH2OH   H-C-OH C=O Aldehyde  in 1 and Ketone  in 2 OH - C-H OH-C-H   H-C-OH H-C-OH   CH2OH CH2OH

Carbohydrates are Polyhydroxy Alcohols with Carbonyl groups Which May Either Be Aldehyde (H-C=O) or Keto (C=O) Groups.

H - C CH2 OH CAN YOU  O  VISUALIZE H- C -OH C EITHER   ALDEHYDE OH- C - H OH - C -H OR   KETONE H- C -OH H- C- OH GROUP IN   THIS H- C -OH H- C- OH POLYHYDROX   Y ALCOHOL? CH 2OH CH2 OH

H - C CH OH HOH 2  O  H- C -OH C NO! BUT   HYDROLYSIS OH- C - H OH - C -H OF THIS   COMPOUND YIELDS TWO H- C -OH H- C- OH COMPOUNDS   WITH H- C -OH H- C- OH ALDEHYDE   OR KETONE CH 2OH CH2 OH GROUPS H - C =O CH OH HOH 2  O  H- C -OH O= C NO! BUT   HYDROLYSIS OF THIS OH- C - H OH - C -H COMPOUND   YIELDS TWO H- C -OH H- C- OH COMPOUNDS   WITH H- C -OH H- C- OH ALDEHYDE   OR KETONE CH 2OH CH2 OH GROUPS MANY POLYHYDROXY ALCOHOLS MAY NOT HAVE AN ACTIVE ALDEHYDE OR KETONE GROUP BUT THEY MAY YIELD THEM ON HYDROLYSIS. THEY ARE ALSO DESIGNATED AS CARBOHYDRATES. THEREFORE, THE COMPLETE DEFINITION OF CARBOHDRATES IS:

CARBOHYDRATES ARE POLYHYDROXYL ALCOHOLS WITH POTENTIALLY ACTIVE CARBONY GROUPS WHICH MAY BE EITHER AN ALDEHYDE OR KETONE GROUP. THEY ALSO CONTAIN THOSE COMPOUNDS, WHICH YIELD THEM ON HYDROLYSIS.

CLASSIFICATION OF CARBOHYDRATES

Carbohydrates are mainly classified into four different groups:

 Monosachharides

 Disaccharides

 Oligosaccharides

 Polysaccharides

MONOSACCHARIDES

are those carbohydrates which Cannot be Hydrolyzed further into more simple carbohydrates.

 Thus, they are the Simplest form of Carbohydrates.

 Familiar examples are: Glucose, Fructose, Ribose & Galactose.

MONOSACCHARIDES ARE FURTHER CLASSIFIED ON THE BASIS OF:  Aldehyde or Ketone Group:

Aldomonosaccharides (Aldoses).

Ketomonosaccharides (Ketoses).  Carbon Chain Length.

Trioses.

Tetroses.

Pentoses.

Hexoses.

Heptoses. CARBONYL GROUP

H-C=O CH2OH   H-C-OH C=O  

OH-C-H GLUCOSE OH-C-H   H-C-OH FRUCTOSE--> H-C-OH   H-C-OH H-C-OH  

CH2OH CH2OH CARBON CHAIN H-C=O  H-C=O H-C-OH   OH-C-H OH-C-H  GLUCOSE H-C-OH  H-C-OH ARABINOSE-->   H-C-OH H-C-OH   CH2OH

CH2OH EXAMPLES OF MONOSACCHARIDES

NO. OF CARBON ALDO KETO ATOMS

3C TRIOSE GLYCERALDEHY DIHYDROXYACET DE ONE

4C TETROSE ERYTHROSE ERYTHRULOSE

5C PENTOSE RIBOSE, XYLOSE RIBULOSE, XYLULLOSE

6C HEXOSE GLUCOSE, FRUCTOSE GALACTOSE, MANNOSE GLYCERALDEHYDE  GLYCERALDEHYDE IS THE SIMPLEST (PARTICULARLY ALDOSES)

 IT CANNOT BE HYDROLYZED FURTHER.

 IT IS THE SMALLEST POSSIBLE STRUCTURE THAT IS A CARBOHYDRATE CANNOT HAVE LESS THAN 3 CARBON ATOMS.

 GENERAL FORMULA OF MONOSACCHARIDE: (C•H2O)N (WHERE N IS ANY NUMBER OF THREE OR GREATER)

ISOMERISM

 Isomers are basically molecules that have the same chemical formula but they differ in their chemical structures.

 Asymmetric Carbon is an important determinant of Isomerism.

 Asymmetric Carbon is that Carbon which is attached with four different groups.

STRAIGHT CHAIN STRUCTURE OF TYPICAL MONOSACCHARIDE (GLUCOSE) Anomeric Carbon

Epimeric Carbons

Penultimate Carbon Terminal Alcohol Carbon THE ASSIGNMENT OF D OR L IS MADE ACCORDING TO THE ORIENTATION OF THE PENULTIMATE CARBON

If the Hydroxyl Group is on the right the molecule is a D sugar, Otherwise It is an L sugar.

OH H L-Sugar : D-Sugar D AND L ISOMERISM PRODUCE MIRROR IMAGES EPIMERISM

 Isomers which differ from each other only with regard to OH group on a single asymmetric carbon atom. OPTICAL ISOMERS

 When a beam of polarized light is passed through sugars, they will be rotated either towards right or left.

 Right Rotation (dextrorotatory) E.g. D- Glucose, D-Fructose

 Left Rotation (levorotatory) E.g. L- Glucose, L-Fructose MONOSACCHARIDE DERIVATIVES OF BIOLOGICAL IMPORTANCE

 Oxidation Products (Sugar Acids)

 Reduction Products (Sugar Alcohols).

 Amino Sugars.

 Sugar Phosphates. OXIDATION PRODUCTS (SUGAR ACIDS)

 When oxidized under proper conditions, Aldoses may form three types of acids (Sugar Acids):

 Uronic Acids.

 Aldonic acids.

 Saccharic Acids.

 Type of sugar Acid produced depends on which carbon is oxidized. H-C=O  H-C-OH  OH-C-H Oxidation Of Aldose  At Primary Alcohol H-C-OH (Terminal Carbon)  H-C-OH  CH2OHCOOH H -COOHC=O  H-C-OH Oxidation Of Aldose  At OH-C-H Carbonyl Carbon  (Aldehyde Group) H-C-OH  H-C-OH 

CH2OH HCOOH-C=O  H-C-OH  Saccharic Acid OH-C-H Oxidation Of Aldose  At Both Aldehyde & H-C-OH  Terminal Carbons H-C-OH  CH2OHCOOH EXAMPLES OF ALDOSES WITH THEIR CORRESPONDING URONIC ACIDS ARE: Sugar Uronic Acids

Glucose , Iduronic acid ------Mannose Mannuronic acid ------Galactose Galacturonic acid ------EXAMPLES OF ALDOSES WITH THEIR CORRESPONDING ALDONIC ACIDS ARE: Sugar Aldonic Acids

Glucose Gluconic acid ------Mannose Mannonic acid ------Galactose Galactonic acid ------Amino Sugar: Substitution of Amino Group for a H-C=O  Hydroxyl Group of a H-C-OHNH2 Sugar Results in the  Formation of an OH-C-H  Amino Sugar. H-C-OH The Amino Group  is attached to H-C-OH  Carbon 2. CH2OH COMMON EXAMPLES OF AMINO SUGARS (AMINOSACCHARIDES)

Galactosamine

Glucosamine SUGAR ALCOHOLS; REDUCTION PRODUCTS

 Sugar Alcohols are obtained by reduction of Monosaccharides (Both Aldoses and Ketoses) and disaccharides.

 Sugar alcohols, also known as Polyols, Polyhydric Alcohols, or Polyalcohols. SUGAR ALCOHOLS ARE THE HYDROGENATED FORMS OF THE ALDOSES OR KETOSES H- C=O + H 2 CH2OH   H-C-OH H-C-OH   OH-C-H OH-C-H   H-C-OH H-C-OH   H-C-OH H-C-OH   CH OH 2 CH2OH Glucose Sorbitol Sugars with their Corresponding Alcohols Glyceraldehyde & Glycerol Dihydroxyacetone Glucose Sorbitol (Glucitol) Mannose Mannitol Fructose Sorbitol & Mannitol Galactose Dulcitol Ribose Ribitol Erythrose Erythritol Xylose Xylitol Lactose Lactitol Maltose Maltitol Sugar Phosphates Phosphate Esters formed by various Monosaccharides are of Great Importance in Metabolic Reactions. Sugar phosphates of biological importance. Ribose and Deoxyribose in Nucleic Acids are Phosphate Esters of these monosaccharides. Phosphates of Glucose, Fructose and Glyceraldehyde etc. are important intermediate compounds in carbohydrate metabolism of almost all the cells. DISACCHARIDES

Two Joined Monosaccharides.

Sucrose: Glucose + Fructose

Maltose: Glucose + Glucose

Lactose: Glucose + Galactose OLIGOSACCHARIDES

Composed Of:

 Three To Ten Monosaccharide Units.

 E.g. Fructooligosaccharides POLYSACCHARIDES

 Larger Than Ten Monosaccharide Units.

Can Reach Many Thousands Of Units.

 Homopolysaccharides.

 Heteropolysaccharides. HOMOPOLYSACCHARIDES

 Similar Types of Monosaccharide Units.

Starch

Glycogen

Cellulose HETEROPOLYSACCHARIDES

 Different Types of Monosaccharide Units.

Mucopolysaccharides (Glycosaminoglycans that contain galactose and amine sugars)

Agar (Contains various sugars like Glucose, Galactose) REFERENCES

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Thank You…..