CARBOHYDRATES

CARBOHYDRATES 

-          Carbohydrates are organic compounds that have a molecular formula Cx(H2O)y.

-          These perform vital roles in living organisms.

-          A monosaccharide is the simplest carbohydrates.

-          Carbohydrates can be classified into 4 groups based upon the no. of they have.

o   Monosaccharide

o   Disaccharide

o   Oligosaccharide

o   Polysaccharide.

-          Carbohydrates are of great importance in organisms.

-          Starch (a polysaccharide) serves as an energy store in plants.

-          Cellulose and lignin (polysaccharide) make the plant cell wall.

-          Glucose (monosaccharide) is used for the production of energy in our body.

-          Sucrose (a disaccharide) is called the cane sugar.

MONOSACCHARIDE

-          Monosaccharides are defined as polyhydroxy aldehydes or ketones.

-          Monosaccharides can be further divided into groups upon the number of carbon atoms they have.

o   Triose (3 carbon atoms) eg: - glycerose.

o   Tetrose (4 carbon atoms) eg: - erythrose

.

o   Pentose (5 carbon atoms) eg: - ribulose.

o   Hexose (6 carbon atoms) eg: - glucose and fructose.

o   Heptose (7 carbon atoms) eg: - glucoheptose.

-          A carbon atom to which four different groups are attached is called a chiral carbon.

 

-          Because of this chiral carbon monosaccharides show isomerism.

DISACCHARIDES

-          These are formed when two monomers are attached by glycosidic bond.

-          Glycosidic bond is formed by removal of a water molecule from two monosaccharides.

-          Example of disaccharides: -

o   Sucrose (glucose and fructose as its monomer unit).

o    Lactose (glucose and galactose as its monomer unit).

o   Maltose (glucose and glucose as its monomer unit).

REDUCING SUGARS

-          Carbohydrates that have a free aldehyde at the C1 or free ketone at C2 are called reducing sugars.

-          Eg: - glucose, fructose, lactose, maltose.

NON-REDUCING SUGARS

-          These don’t have free aldehyde or ketone groups.

-          Eg: - sucrose and glycogen.

POLYSACCHARIDES

-          Polysaccharides are forms when more than two monosaccharides are attached by glycosidic bond.

-           Polysaccharides are further classified on the types of monomer units they yield upon hydrolysis.

-           

o   Homopolysaccharides: - These yield same monomer units upon hydrolysis.

§   Amylose is a polysaccharide of glucose molecules.

§  Glycogen.

§  Cellulose is a polysaccharide of glucose molecules.

o   Heteropolysaccharides: - These yield different monomer units upon hydrolysis.

§  Mucopolysaccharide.

§  Heparin.

-          Cellulose is the most abundant polysaccharide.

-          Polysaccharides are usually used as food storage forms or main ingredients of cell walls.