BIOMOLECULES
Carbohydrates
Carbohydrates (cont.)
• Can be divided into 3
groups based on their
size:
– Monosaccharides: simple
sugars like glucose,
galactose and fructose
– Disaccharides: double
sugars like sucrose, lactose
and maltose
– Polysaccharides: chains
of sugars like starch,
glycogen, cellulose and
chitin
Monosaccharides
• Glucose - "Blood sugar" is the immediate
source of energy for cellular respiration. It
is a moderately sweet sugar found in
vegetables and fruit.
• Galactose - Galactose is not normally
found in nature, but is mostly hydrolyzed
from the disaccharide lactose, which is
found in milk.
• Fructose - Fructose is also called the fruit
sugar. Fructose is found in fruits, honey,
and the sole sugar in bull and human
semen.
Disaccharides
• Lactose is the second most common double
sugar and is found in milk. It is a combination of
glucose and another small sugar called
galactose.
• Maltose is the third most common double sugar.
It is not found in the foods that we eat. Instead,
the body makes it when a person eats foods that
contain starches such as potatoes and bread.
• Sucrose is the most common double sugar that
people eat in common foods. It is found in fruits,
potatoes, pasta, breads, cereals and other
common foods.
Polysaccharides
• Starch: a storage polysaccharide in plants
• Glycogen: a highly branched storage
polysaccharide in animals.
• Cellulose: a structural polysaccharide in
plants. Cellulose is a major component of
plant cell walls.
• Chitin: a structural polysaccharide in fungi
and animals. Chitin stiffens the cell walls
of fungi and some algae and is an
important component of the exoskeletons
of insects and crustaceans.