DISACCHARIDES, POLYSACCHARIDE, ETC...

Disaccharides

- A disaccharide is a double sugar

- They’re made by joining two monosaccharides

- Involves removing a water molecule 

(condensation)

- Bond called a GLYCOSIDIC bond

Disaccharides

Common disaccharides include:

Sucrose (table sugar)

Lactose (Milk Sugar)

Maltose (Grain sugar)

Disaccharides

Sucrose is composed of glucose +  fructose

Maltose is composed of 2 glucose molecules

Lactose is made of galactose + glucose

Polysaccharides

- Complex carbohydrates

- Composed of many sugar monomers linked together

- Polymers of monosaccharide chains

Starch

- Starch is an example of a polysaccharide in plants

- Plant cells store starch for energy

- Potatoes and grains are major sources of starch in the human diet

Glycogen

- Glycogen is an example of a polysaccharide in animals

- Animals store excess sugar in 

the form of glycogen

- Glycogen is similar in structure to starch because BOTH are made of glucose monomers

Cellulose

- Cellulose is the most abundant organic compound on Earth

- It forms cable-like fibrils in the tough walls 

that enclose plants

- It is a major component of wood

It is also known as dietary fiber

Dietary Cellulose

- Most animals cannot derive nutrition from fiber

- They have bacteria in their digestive 

tracts that can break down cellulose

Sugars in water

- Simple sugars and double sugars dissolve readily in water

- They are hydrophilic, or “water-loving”

- OH groups make them water soluble

Lipids

- Lipids are hydrophobic –”water fearing”

- Do NOT mix with water

- Includes fats, waxes, steroids, & oils

Function of Lipids

- Fats store energy, help to insulate the body, and cushion and protect organs 

Types of Fatty Acids

- Saturated fatty acids have the maximum number of hydrogens bonded to the carbons (all single bonds between carbons)

- Unsaturated fatty acids have less than the maximum number of hydrogens bonded to the carbons (a double bond between 

carbons)

Triglyceride

- Monomer of lipids

- Composed of Glycerol & 3 fatty acid chains

- Glycerol forms the “backbone” of the fat

Fats in Organisms

- Most animal fats have a high proportion of saturated fatty acids & exist as solids at room temperature (butter, margarine, shortening)

Fats in Organisms

- Most plant oils tend to be low in saturated fatty acids & exist as liquids at room temperature (oils)

Fats

- Dietary fat consists largely of the molecule triglyceride composed of glycerol and three fatty acid chains

- Condensation links the fatty acids to Glycerol

Lipids & Cell Membranes

- Cell membranes are made of lipids called 

phospholipids

- Phospholipids have a head that is polar & 

attract water (hydrophilic)

- Phospholipids also have 2 tails that are 

nonpolar and do not attract water 

(hydrophobic)

Steroids

- The carbon skeleton of steroids is bent to form 4 fused rings

- Cholesterol is the “base steroid” from 

which your body produces other steroids

- Estrogen & testosterone are also steroids

Synthetic Anabolic Steroids

- They are variants of testosterone

- Some athletes use them to 

build up their muscles quickly. They can pose serious health risks