Summary OCR A/AS-Level Biology 2.2.3 Carbohydrates

Carbohydrates
Monosaccharides
 Single molecules (monomers)  Examples:
 Soluble o Glucose
 Single ring or straight chain o Fructose
 Roles: o Galactose
o Energy release o Ribose
o Transported in blood o Deoxyribose
o Monomers for other carbohydrates

Disaccharides
 Two monosaccharides covalently bonded  Examples:
 Soluble o Maltose (glucose +
 Two joined rings glucose)
 Roles: o Sucrose (glucose +
o Energy release fructose)
o Energy storage o Lactose (glucose +
o Transport in plants galactose)

Polysaccharides
 Many monosaccharides covalently bonded  Examples:
 Insoluble o Starch (alpha glucose)
 Long chains (may be branched or straight) o Glycogen (alpha
 Roles: glucose)
o Energy storage o Cellulose (beta
o Structural components glucose)

Glycosidic Bonds
 Formed from a condensation reaction between the hydroxyl groups on carbons 1 and 4,
called a 1-4 bond
 Two hydrogen and one oxygen atoms separate to form a water molecule, leaving a
glycosidic bond on the remaining oxygen atom