1. CHAPTER 4 : CHEMICAL COMPOSITION OF THE CELL

3. CARBOHYDRATES
 Contain the element carbon, hydrogen &
oxygen
 3 main groups : monosaccharides,
disaccharides & polysaccharides

4. Monosaccharides
 Basic building blocks
 Simple sugar as glucose, fructose &
galactose
 Consist of single chemical group made up
of a ring of carbon, hydrogen & oxygen
atoms
 Reducing sugars
 Can be detected by using Benedict’s test.

5. Disaccharides
 Complex sugars
 Consist of two monosaccharides
combined chemically through
condensation.
 Mono + mono  disaccharides + water
 Eg.: maltose (malt sugar), sucrose (cane
sugar), lactose (milk sugar)

6. Disaccharides (continue...)
 Glucose + glucose  maltose + water
 Glucose + fructose  sucrose + water
 Glucose + galactose  lactose + water
 Can be broken down into
monosaccharides through hydrolysis
 All are reducing sugar except sucrose

7. Polysaccharides
 Large complex sugar
 Many monosaccharides are joined
together to form long chain of simple
sugar called polymers.
 Eg. : starch, glycogen & cellulose