UNIT 4: CHEMICALS OF LIFE
Carbohydrates (C, H, O)
Sugar Polysaccharides
Monosaccharide -simple Disaccharides - complex Not sweet, insoluble,
sugars sugars many joined simple
Sweet, soluble, small 2 joined simple sugars sugars
Glucose: together, sweet, Cellulose: build cell
transportation in soluble wall
animal Maltose Starch: storage in
Sucrose: plant
transportation in plant Glycogen: storage in
animal
Cellulose, starch,
glycogen are made
from glucose
Testing for carbohydrate:
Reducing sugar: Benedict’s solution Starch: Iodine solution
1. Cut, grind food into small pieces then dissolve Blue-black: there’s starch
with water Orange-brown: no starch
2. Add Benedict’s solution
3. Heat
Brick-red: there’s reducing sugar
Blue: no sugar
Fats – Lipids (C, H, O)
Made of 3 fatty acids molecules + 1 glycerol molecules
Release energy when carb is unavailable
Adipose tissue: layer of fat underneath the skin which insulates the body and
store energy
Testing for fat: Ethanol emulsion test
1. Chop or grind food to put in test tube
2. Add ethanol, shake thoroughly
3. Put water in another test tube
4. Pour only the liquid part in the first test tube into the second test tube
Milky appearance: emulsion of fat droplets
Protein (C, H, O, N): made of long chains of amino acids in order that make new
cells and repair damage
Different sequences of amino acids give different shapes to protein molecules
Protein Function
Haemoglobi Red pigment in red blood cell, contains iron
n Combine reversely with oxygen ( transport from lung to respiring
Carbohydrates (C, H, O)
Sugar Polysaccharides
Monosaccharide -simple Disaccharides - complex Not sweet, insoluble,
sugars sugars many joined simple
Sweet, soluble, small 2 joined simple sugars sugars
Glucose: together, sweet, Cellulose: build cell
transportation in soluble wall
animal Maltose Starch: storage in
Sucrose: plant
transportation in plant Glycogen: storage in
animal
Cellulose, starch,
glycogen are made
from glucose
Testing for carbohydrate:
Reducing sugar: Benedict’s solution Starch: Iodine solution
1. Cut, grind food into small pieces then dissolve Blue-black: there’s starch
with water Orange-brown: no starch
2. Add Benedict’s solution
3. Heat
Brick-red: there’s reducing sugar
Blue: no sugar
Fats – Lipids (C, H, O)
Made of 3 fatty acids molecules + 1 glycerol molecules
Release energy when carb is unavailable
Adipose tissue: layer of fat underneath the skin which insulates the body and
store energy
Testing for fat: Ethanol emulsion test
1. Chop or grind food to put in test tube
2. Add ethanol, shake thoroughly
3. Put water in another test tube
4. Pour only the liquid part in the first test tube into the second test tube
Milky appearance: emulsion of fat droplets
Protein (C, H, O, N): made of long chains of amino acids in order that make new
cells and repair damage
Different sequences of amino acids give different shapes to protein molecules
Protein Function
Haemoglobi Red pigment in red blood cell, contains iron
n Combine reversely with oxygen ( transport from lung to respiring
