MOLECULES OF LIFE: THERE ARE FOUR MAIN CLASSES OF ORGANIC COMPOUNDS ESSENTIAL TO LIFE

1. CARBOHYDRATES 2. LIPIDS 3. PROTEINS 4. NUCLEIC ACIDS

SEVERAL OF THESE MOLECULES ARE CONSIDERED TO BE MACROMOLECULES.

A. CARBOHYDRATES: 1.ARE ORGANIC COMPOUNDS MADE OF ELEMENTS – C,H,O

2. EXIST AS MONOSACCHARIDES, DISACCHARIDES AND POLYSACCHARIDES

3. MONOSACCHARIDES : HAVE CHEMICAL FORMULA C6H12O6

a.ARE SIMPLE SUGARS INCLUDING: (1)GLUCOSE – MAIN SOURCE OF ENERGY FOR CELLS

(2) FRUCTOSE – IN FRUIT 3) GALACTOSE – IN MILK

. SINCE MANY MONO- SACCHARIDES HAVE THE SAME CHEMICAL FORMULA, THEY ARE DIFFERENT STRUCTURALLY.

MOLECULES WITH THE SAME FORMULA BUT DIFFERENT STRUCTURAL ARE CALLED: ISOMERS

c. GENERAL CHEMICAL FORMULA FOR CARBOHYDRATES IS (CH2O) N

4. DISACCHARIDES a. DOUBLE- SUGAR

b. MADE OF TWO SIMPLE SUGARS JOINED THROUGH A CONDENSATION REACTION

c. INCLUDES: (1)LACTOSE: A COMBINATION OF GLUCOSE + GALACTOSE

(2) SUCROSE: A COMBINATION OF GLUCOSE + FRUCTOSE

(3) MALTOSE: A COMBINATION OF GLUCOSE +GLUCOSE

5. POLYSACCHARIDES: a.COMPLEX MOLECULES OF THREE OR MORE MONOSACCHARIDES

b. INCLUDES (1)GLYCOGEN – GLUCOSE STORAGE IN ANIMALS, FOUND IN THE LIVER AND IN MUSCLES – QUICK ENERGY

(2) CELLULOSE – FOUND IN PLANT CELL WALLS GIVES STRENGTH AND RIGIDITY, PEOPLE CANNOT DIGEST CELLULOSE, YET IT IS AN IMPORTANT PART OF A HEALTHY DIET. WHY?

(3) STARCH – PLANT STORAGE OF GLUCOSE

(4) CHITIN – MAKES UP EXOSKELETONS OF ARTHROPODS

6. Building and breaking down carbohydrates: both reactions involve enzymes and water a. Building – called condensation or dehydration synthesis:

b. Breaking a disaccharide into two monosaccharides is called hydrolysis