Biochemistry of Cells

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Monosaccharides are the main fuel that cells use for cellular work

ATP

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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

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Disaccharides

Common disaccharides include:

Sucrose (table sugar)

Lactose (Milk Sugar)

Maltose (Grain sugar)

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Disaccharides

Sucrose is composed of glucose + fructose

Maltose is composed of 2 glucose molecules

Lactose is made of galactose + glucose

GLUCOSE

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Polysaccharides

Complex carbohydrates

Composed of many sugar monomers linked together

Polymers of monosaccharide chains

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Examples of Polysaccharides

Starch

Glycogen

Cellulose

Glucose Monomer

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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

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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

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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

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Cellulose

SUGARS

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Dietary Cellulose

Most animals cannot derive nutrition from fiber

They have bacteria in their digestive tracts that can break down cellulose

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Sugars in Water

Simple sugars and double sugars dissolve readily in water

They are hydrophilic, or “water-loving”

WATER MOLECULE

SUGAR MOLECULE

-OH groups make them water soluble

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Lipids