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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 PowerPointLectures forBiology: Concepts & Connections

CHAPTER 3The Molecules of Cells

Modules 3.13.3

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Lifes diversity results from the

variety of molecules in cells

A spiders web-building skilldepends on its DNA molecules

DNA also determines thestructure of silk proteins

These make a spiderwebstrong and resilient

Spider Silk: Stronger than Steel

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The capture strand contains a single coiled silkfiber coated with a sticky fluid

The coiledfiber

unwinds tocaptureprey andthen recoils

rapidly

Coiled fiber

of silk protein

Coating of

capture strand

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Lifes structural and functional diversity resultsfrom a great variety of molecules

A relatively small number of structural patternsunderlies lifes molecular diversity

INTRODUCTION TO ORGANIC COMPOUNDSAND THEIR POLYMERS

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A carbon atom forms four covalent bonds

It can join with other carbon atoms to makechains or rings

3.1 Lifes molecular diversity is based on theproperties of carbon

Figure 3.1, top part

Structural

formula

Ball-and-stick

model

Space-filling

model

Methane

The 4 single bonds of carbon point to the corners of a tetrahedron.

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Carbon skeletons vary in many ways

Ethane PropaneCarbon skeletons vary in length.

Butane Isobutane

Skeletons may be unbranched or branched.

1-Butene 2-Butene

Skeletons may have double bonds, which can vary in location.

Cyclohexane Benzene

Skeletons may be arranged in rings.Figure 3.1, bottom part

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Functional groups are the groups of atoms thatparticipate in chemical reactions

Hydroxyl groups are characteristic of alcohols

The carboxyl group acts as an acid

3.2 Functional groups help determine theproperties of organic compounds

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Table 3.2

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Most of the large molecules in living things aremacromolecules called polymers

Polymers are long chains of smaller molecular

units called monomers

A huge number of different polymers can bemade from a small number of monomers

3.3 Cells make a huge number of large moleculesfrom a small set of small molecules

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Cells link monomers to form polymers bydehydration synthesis

1 2 3

Unlinked monomer

Removal of

water molecule

1 2 3 4

Longer polymerFigure 3.3A

Short polymer

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Polymers are broken down to monomers by thereverse process, hydrolysis

Coating of

capture strand

1 2 3

Addition of

water molecule

1 2 3

Figure 3.3B

4