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BIOLOGYCONCEPTS & CONNECTIONS

Fourth Edition

Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Neil A. Campbell Jane B. Reece Lawrence G. Mitchell Martha R. Taylor

From PowerPoint Lectures forBiology: Concepts & Connections

CHAPTER 3The Molecules of Cells

Modules 3.43.10

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Carbohydrates are a class of molecules They range from small sugars to large

polysaccharides

Polysaccharides are long polymers of monomers

CARBOHYDRATES

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Monosaccharides are single-unit sugars

These molecules typically have a formula that isa multiple of CH2O

Each molecule contains hydroxyl groupsand a carbonyl group

Monosaccharidesare the fuels forcellular work

3.4 Monosaccharides are the simplestcarbohydrates

Figure 3.4A

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The monosaccharides glucose and fructose areisomers

They contain the same atoms but in differentarrangements

Glucose FructoseFigure 3.4B

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Many monosaccharides form rings, as shown here

for glucose

Abbreviated

structure

Figure 3.4C

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Monosaccharides can join to formdisaccharides, such as sucrose (table sugar) andmaltose (brewing sugar)

3.5 Cells link single sugars to form disaccharides

Glucose Glucose

MaltoseFigure 3.5

Sucrose

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Various types of molecules, including non-

sugars, taste sweet because they bind to sweetreceptors on the tongue

3.6 Connection: How sweet is sweet?

Table 3.6

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These large molecules are polymers of

hundreds or thousands of monosaccharideslinked by dehydration synthesis

3.7 Polysaccharides are long chains of sugar units

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Starch and glycogen are polysaccharides thatstore sugar for later use

Cellulose is a polysaccharide in plant cell walls

Figure 3.7

Starch granules in

potato tuber cells

Glucose

monomer

STARCH

GLYCOGEN

CELLULOSE

Glycogen granules

in muscle tissue

Cellulose fibrils ina plant cell wall

Cellulose

molecules

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These compounds are composed largely ofcarbon and hydrogen

They are not true polymers

They are grouped togetherbecause they do not mixwith water

3.8 Lipids include fats, which are mostly energy-storage molecules

Figure 3.8A

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Fats are lipids whose main function is energystorage

They are also called triglycerides

A triglyceride molecule consists of one glycerolmolecule linked to three fatty acids

Figure 3.8B

Fatty acid

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The fatty acids of unsaturated fats (plant oils)contain double bonds

These prevent them from solidifying at roomtemperature

Saturated fats (lard) lack double bonds

They are solid at room temperature

Figure 3.8C

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Phospholipids are a major component of cellmembranes

Waxes form waterproof coatings

Steroidsare oftenhormones

3.9 Phospholipids, waxes, and steroids are lipidswith a variety of functions

Figure 3.9

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Anabolic steroids are usually synthetic variantsof testosterone

Use of these substances

can cause serious healthproblems

3.10 Connection: Anabolic steroids and relatedsubstances pose health risks

Figure 3.10