T.Y.B.Sc Semester VI Botany Paper III Unit I : Plant Physiology Biomolecule: Carbohydrates By Mrs. Mandakini R Ingle Department of Botany Satish Pradhan Dnyanasadhana College, Thane (w)

Classification of carbohydrates Tetrasaccharides stachyose Octoses nososes

MONOSACCHARIDES

DISACCHARIDES

MALTOSE Constructed by a condensation reaction Composed of two glucose molecules Possesses an alpha bond Commonly produced by fermentation reactions called malting Most maltose digested is the result of starch digestion

SUCROSE Constructed by a condensation reaction Composed of one glucose and one fructose Possesses an alpha bond Commonly called table sugar and is found in plants such as sugar cane and maple syrup Purified to form brown, white, and powdered sugars

LACTOSE Constructed by a condensation reaction Composed of one glucose and one galactose Possesses a beta bond Beta bonds are difficult to digest Primary sugar in milk and milk products

Polysaccharides: 1.Pentosans: Araban and xylan 2. Hexosans: i. Glucosans- starch, cellulose, glycogen ii. Fructosans- Inulin iii. Mannans- Mannane iv. Galctans-Galactane 3. Pectic compounds- pectic acid, pectin 4. Gums 5.Amino-hexosans- chitin 6. mucilages

POLYSACCHARIDES Digestible polysaccharides: Starch Amylose Amylopectin Glycogen Non-digestible polysaccharides: fibers Soluble fiber Insoluble fiber

STARCHES 3000 monosaccharides Contain alpha bonds Amylose is straight chain Amylopectin is branched chain High Glycemic Index

GLYCOGEN Storage form of glucose in animals and humans Structure is similar to amylopectin but with more complex branching Numerous alpha bonds Found in liver (400 kcal) and muscles (1400 kcal)

Chemical Composition of Fibers Contain beta bonds Insoluble: not fermented Cellulose Hemicellulose Lignin* Soluble: 1.5-2.5 kcal/g Gum Pectin Mucilage

Monosaccharides Isomerism ( 2 compounds with same mol. Formula) 2. Ring structure (same molecule with diff. ring forms) Isomerism: i. structural ii.stereoisomerism

Structural Isomerism: They have mol. Formula but diff. strut. formulae

Stereoisomerism Same structural and mol. Formula but differ in spatial arrangement of atoms or groups in the molecule D-glucose and D-mannose hav e change in spatial arrangement of Hydrogen and hydroxyl grps

D- molecule is one in which : i. Asymmetric carbon atom is far from aldehyde or ketone grp

Mirror images in L- glucose and L-mannose: optical isomerism

Monosaccharides (D-aldoses) CH2OH C=O

The Fischer convention, the basis for the D- configuration in sugars comes from D-glyceraldhyde’s configuration around its asymmetric carbon. Epimers differ in configuration around one carbon atom i.e. D-glucose and D-mannose but D-glactose and D-glucose are not epimers because they very around two carbon atoms. There are 2n-2 stereoisomers

Carbohydrates are classified as to the nature of the carbonyl group : ketone = ketose aldehyde = aldose Triose Tetrose Pentose Hexose 2(n-3) stereoisomers of ketoses

Monosaccharides can form ring structures

Ring structure: Pyranose ring- stable , C-1 and C-5 are linked by O atom, exhibited by pentoses and hexoses This may be written as straight carbon chain- carbon rings

Furanose ring: less stable, C-1 and C-4 are linked by O atom, exhibited by pentoses and hexoses. This may be written as closed carbon rings or as chain- carbon rings

a-amylose

Cellulose (polyglucose)

Thank you……….