CARBOHYDRATES

INTRODUCTION

• According to old theory carbohydrates are hydrates of carbon, which made up of carbon, hydrogen & oxygen.

• Formula of carbohydrates is CnH2nOn.

• There are some exceptions fatty acids & acetic acid have same formula like carbohydrates but they are not carbohydrates.

• According to new theory carbohydrates are poly-hydroxy aldehyde or ketone which produce them on hydrolysis.

Classification of carbohydrates:

Flowchart of carbohydrate classification: https://assets.zyrosite.com/AzG8ZkQ8NDU2ebR1/carbohydrate-flowchart-mePG1VWa4bueK9Mj.pdf

• Carbohydrates are classified in 4 classes-

1. Monosaccharide

2. Disaccharide

3. Oligosaccharide

4. Polysaccharide

Monosaccharide:

• Simple sugar

• Contain only one sugar unit

• Building block of carbohydrates

• Divide on the basis of –

  a. No. of carbon atom

  • Trioses (3c)

  • Tertaoses (4c)

  • Pentaoses (5c)

  • Hexoses (6c)

  b. Functional group

  • Aldehyde (CHO)

  • Ketone (C=O)

• Common monosaccharides include:

  • Glucose: Primary source of energy for cells.

  • Fructose: Found in fruits & honey

  • Galactose: Found in dairy products.

Disaccharide:

• It is composed with two sugar unit (monosaccharides), linked together by glycosidic bond.

• Common disaccharides include:

  • Sucrose: Glucose + Fructose

  • Lactose: Glucose + Galactose (found in milk)

  • Maltose: Glucose + Glucose (formed during the digestion of starch).

Oligosaccharide

• It consist of a small number 3 to 10 monosaccharide units.

• They are found in certain foods

• Important role in digestion and gut health.

• Common oligosaccharides include:

  • Starchose

  • Raffinose

Polysaccharide

• It contain long monosaccharide chain which linkage together by glycosidic linkage.

• They are either linear or branched structure

• It can be further hydrolysis on simple sugar

• Common polysaccharides include:

  • Starch: A storage form of energy in plants.

  • Glycogen: A storage form of energy in animals.

STRUCTURE OF CARBOHYDRATES

• Carbohydrates consist carbon, hydrogen & oxygen

• General formula is CnH2nOn

• They are organic compound organized in the form of aldehyde & ketone

• The building block of carbohydrates is monosaccharide

• Carbohydrate can be structurally represented in any of the three form

- Open chain structure

- Hemi acetal structure

- Haworth structure

FUNCTION OF CARBOHYDRATES

• Carbohydrates are the most abundant source of energy for the body, especially glucose.

• Excess glucose is stored as glycogen in the liver and muscles for later use.

• Essential for the oxidation of fat

• Carbohydrate add flavor to diet.

• Polysaccharides like cellulose provide structural support to cells and tissues.

• Provide carbon for synthesis of non-amino acids.

• Carbohydrates impact blood sugar levels, regulated by insulin.

• They are structural component for many organism

• Serve as the storage form of energy to meet the immediate demand of the body.

• Also help in modulation of immune system.

• In animal they are important constituent off connective tissue.

PROPERTIES OF CARBOHYDRATES

# PHYSICAL PROPERTIES –

1. Stereoisomerism: compound having the same structure formula but they differ in sptial configuration.

Example: D - glucose & L – glucose

2. Optical activity: It is the rotation of plane polarized light forming (+) glucose & (-) glucose.

3. Annomerism: It is the spatial configuration with respect to the first carbon atom in aldoses & the seconds carbon atom in ketoses.

# CHEMICAL PROPERTIES –

1. Osazone formation: Osazone are carbohydrate derivatives when sugar are reacted with an excess of phenylhydrazine.

2. Reduction of alcohols: The C=O groups in open chain form of carbohydrates can be reduced to alcohol.

3. Oxidations: Monosaccharide are reducing sugar if their carbomyl groups oxidize to give carboxylic acids.