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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
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