Carbohydrates
All carbohydrates contain carbon, hydrogen and oxygen and are divided into 3
groups:
Monosaccharides
Disaccharides
Polysaccharides
These al refer to a sugar or sweet substance and all carbohydrates have the
formula Cx(H2O)y
Monosaccharides
These have the general formula (CH2O)n and consist of one sugar molecule. The
main types of monosaccharides are trioses (3 carbons), pentoses (5 carbons)
and hexoses (6 carbons).
Common hexoses: glucose, fructose and galactose
Common pentoses: ribose and deoxyribose
Ribose is one of the molecules used to make RNA and ATP.
Deoxyribose is one of the molecules used to make DNA.
Hexoses have the molecular formula C6H12O6
Structural formula of glucose
Roles of monosaccharides in living organisms
1. Used as a source of energy in respiration due to the large number of
carbon-hydrogen bonds. These bonds can be broken to release a lot of
energy, which is transferred to make ATP from ADP and phosphate.
Glucose is the most important monosaccharide in energy metabolism.
2. Building blocks for larger molecules. Glucose is used to make
polysaccharides such as starch, glycogen and cellulose.
All carbohydrates contain carbon, hydrogen and oxygen and are divided into 3
groups:
Monosaccharides
Disaccharides
Polysaccharides
These al refer to a sugar or sweet substance and all carbohydrates have the
formula Cx(H2O)y
Monosaccharides
These have the general formula (CH2O)n and consist of one sugar molecule. The
main types of monosaccharides are trioses (3 carbons), pentoses (5 carbons)
and hexoses (6 carbons).
Common hexoses: glucose, fructose and galactose
Common pentoses: ribose and deoxyribose
Ribose is one of the molecules used to make RNA and ATP.
Deoxyribose is one of the molecules used to make DNA.
Hexoses have the molecular formula C6H12O6
Structural formula of glucose
Roles of monosaccharides in living organisms
1. Used as a source of energy in respiration due to the large number of
carbon-hydrogen bonds. These bonds can be broken to release a lot of
energy, which is transferred to make ATP from ADP and phosphate.
Glucose is the most important monosaccharide in energy metabolism.
2. Building blocks for larger molecules. Glucose is used to make
polysaccharides such as starch, glycogen and cellulose.
