Class Activity_ Biomolecules of Life
Activity 1
1. What is the general formula for molecules of carbohydrate?
Contain C, H and O and have C=O and OH functional
groups.
Structural formula is typically (CH2O) n, where n is an
integer from 3-7.
2. Name three biologically important disaccharides and state
where they can be found.
i. Lactose (glucose + galactose) is present in milk.
ii. Sucrose (glucose + fructose) is a transport form of sugar used by plants and harvested by humans for
use in food.
iii. Maltose (two glucose units) is present in germinating seeds.
3. Starch and cellulose are high molecular weight polysaccharides.
Which hexose sugar forms their basic unit?
Starch - polymer of D-glucose units
Composed of β-glucose units
4. What is the essential structural difference between starch and cellulose?
Starch - are arranged as unbranched coiled chains, is easily hydrolysed to glucose units. Starch is a
polymer of alpha-glucose. Cellulose is a fibre like structural material - tough, insoluble, and is part of
plant cell walls. Cellulose is a polymer of Beta glucose.
In starch, the sugar molecules are linked together such that they are all in the same orientation. In
cellulose, they are linked together such that alternating molecules are rotated 180 degrees from each
other.
e) Name the storage polysaccharide found in mammals.
Glycogen
2. Give an account of the chemical nature and variety of lipids. Outline the role they play in the life of plants and
animals.
Lipids are greasy or oily compounds with little tendency to dissolve in water. Lipids play important roles as an
energy store, as structural molecules, as hormones and in other diverse roles.
Activity 1
1. What is the general formula for molecules of carbohydrate?
Contain C, H and O and have C=O and OH functional
groups.
Structural formula is typically (CH2O) n, where n is an
integer from 3-7.
2. Name three biologically important disaccharides and state
where they can be found.
i. Lactose (glucose + galactose) is present in milk.
ii. Sucrose (glucose + fructose) is a transport form of sugar used by plants and harvested by humans for
use in food.
iii. Maltose (two glucose units) is present in germinating seeds.
3. Starch and cellulose are high molecular weight polysaccharides.
Which hexose sugar forms their basic unit?
Starch - polymer of D-glucose units
Composed of β-glucose units
4. What is the essential structural difference between starch and cellulose?
Starch - are arranged as unbranched coiled chains, is easily hydrolysed to glucose units. Starch is a
polymer of alpha-glucose. Cellulose is a fibre like structural material - tough, insoluble, and is part of
plant cell walls. Cellulose is a polymer of Beta glucose.
In starch, the sugar molecules are linked together such that they are all in the same orientation. In
cellulose, they are linked together such that alternating molecules are rotated 180 degrees from each
other.
e) Name the storage polysaccharide found in mammals.
Glycogen
2. Give an account of the chemical nature and variety of lipids. Outline the role they play in the life of plants and
animals.
Lipids are greasy or oily compounds with little tendency to dissolve in water. Lipids play important roles as an
energy store, as structural molecules, as hormones and in other diverse roles.
