12 Feb 2019
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Carbohydrates
● Polymers made of monosaccharides (monomer)
● Serve as fuel for the human body
● Composed only of C, H, and O
● Classified by size into monosaccharides, oligosaccharides, and polysaccharides
Monosaccharides
● Also called simple sugars
● Glucose and fructose are examples
Oligosaccharides
● Chains of a few monosaccharides
● One type is a disaccharide, formed by joining two monosaccharides
● Sucrose and maltose are examples
Polysaccharides
● Chains of monosaccharides that store energy or provide structure
● The storage polysaccharide in animals is glycogen, which humans store mainly in liver
and muscle cells
● The storage polysaccharide in plants is starch
Cellulose
● A structural polysaccharide made of repeating units of glucose found in cell walls of
plants
● Humans lack the enzyme necessary to digest cellulose
● An important form of fiber in the human diet
Lipids
● Water-insoluble molecules made of C, H, and O
● Store long-term energy protect vital organs
● Form cell membranes
● Subdivided into triglycerides, phospholipids, and steroids
Triglycerides
● Polymers made of three fatty acids bonded to glycerol through dehydration synthesis
● Examples are fats and oils
● Classified as saturated or unsaturated
Phospholipid molecules have:
● A glycerol head that is polar and hydrophilic (hydro: greek for water, philia: to love) and
mixes with watery environments inside and outside the cell
● A fatty acid tail that is nonpolar and hydrophobic (hydro: water, Phobos: fear) that points
inward and helps hold the membrane together