04 Lecture Presentation.ppt

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LECTURE PRESENTATIONS

For CAMPBELL BIOLOGY, NINTH EDITIONJane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson

2011 Pearson Education, Inc.

Lectures by

Erin Barley

Kathleen Fitzpatrick

Carbon and the Molecular

Diversity of Life

Chapter 4Overview: Carbon: The Backbone of Life

Cells are 70-95% water. The rest is mostly carbon-based compounds

Carbon is unparalleled in its ability to form large,complex, and diverse molecules

Proteins, DNA, carbohydrates, and othermolecules that distinguish living matter are all

composed of carbon compounds


Concept 4.1: Organic chemistry is the study

of carbon compounds

Organic chemistryis the study of compoundsthat contain carbon

Organic compounds range from simplemolecules to colossal ones

Most organic compounds contain hydrogenatoms in addition to carbon atoms


Concept 4.2: Carbon atoms can form diverse

molecules by bonding to four other atoms

Carbon has fourvalence electrons Four covalent bonds with a variety of atoms

Electron configuration is the key to an atomscharacteristics

Four single bonds form a tetrahedron shape single bonds allow rotation

A double bond results in all bonds in sameplane

double bonds cannot rotate 2011 Pearson Education, Inc.


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Figure 4.3

Name andComment

MolecularFormula

(a) Methane

(b) Ethane

CH4

Ball-and-Stick Model

Space-FillingModel

(c) Ethene(ethylene)

C2H6

C2H4

StructuralFormula The valences of carbon and its most frequent

partners (hydrogen, oxygen, and nitrogen) are

the building codethat governs the

architecture of living molecules memorize the valence of H, O, N, and C


Figure 4.4

Molecular Diversity Arising from Carbon

Skeleton Variation

Carbon chains form the skeletons of mostorganic molecules

Carbon chains vary in length and shape

2011 Pearson Education, Inc. Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Molecular Diversity Arising from Carbon SkeletonVariation

Carbon chains can vary in length and shape Each C always makes 4 bonds Hydrocarbonsare molecules that consist of only

carbon and hydrogen

Figure 4.5

Ethane Propane

Butane isobutane

1-Butene 2-Butene

Cyclohexane Benzene


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Figure 4.6

Nucleus

Fat droplets

(b) A fat molecule(a) Part of a human adipose cell

10 m

Hydrocarbons form part of many different organic molecules in

cells

Copyright 2005Pearson Education,Inc. publishingas BenjaminCummings

Isomers

Isomers Are molecules with the same molecular formula but

different structures and properties

Three types of isomers are Structural

Differ in covalent arrangement Geometric

Differ in spatial arrangement around a double bond because double bonds cannot rotate

Enantiomers Have four different groups bonded to an asymmetric carbon; are

mirror images

because bonds are fixed in their relative positions

Figure 4.7(a) Structural isomers

(b) Cis-trans isomers

(c) Enantiomers

cisisomer: The two Xsare on the same side.

transisomer: The two Xsare on opposite sides.

CO2HCO2H

CH3

H NH2

L isomer

NH2

CH3

H

D isomer

Enantiomers (stereoisomers) are important inthe pharmaceutical industry

Two enantiomers of a drug may have differenteffects

Usually only one isomer is biologically active Differing effects of enantiomers demonstrate

that organisms are sensitive to even subtle

variations in molecules


Animation: L-Dopa


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Figure 4.8

Drug

Ibuprofen

Albuterol

ConditionEffective

EnantiomerIneffective

Enantiomer

Pain;inflammation

Asthma

S-Ibuprofen R-Ibuprofen

R-Albuterol S-Albuterol

Concept 4.3: A few chemical groups are key

to the functioning of biological molecules

Functional groupsare the components oforganic molecules that are most commonly

involved in chemical reactions

The number and arrangement of functionalgroups give each molecule its uniqueproperties


Estradiol

Testosterone

Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 4.9 Functional groups

Seven functional groupsare important in thechemistry of life (you need to memorize these sevennames and structures)

Hydroxyl Carbonyl Carboxyl Amino Sulfhydryl Phosphate Plus the methyl group, CH3, which is unreactive but

contributes to the shape of organic molecules and is

important in regulation of activity

Figure 4.9a

STRUCTURE

EXAMPLE

Alcohols(Their specific

names usuallyend in -ol.)

NAME OFCOMPOUND

FUNCTIONALPROPERTIES

(may be writtenHO)

Ethanol

Is polar as a result

of the electronsspending moretime near theelectronegative

oxygen atom.

Can form hydrogenbonds with watermolecules, helpingdissolve organic

compounds such

as sugars.

Hydroxyl


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Figure 4.9b

Carbonyl

STRUCTURE

EXAMPLE

Ketones if the carbonylgroup is within acarbon skeleton

NAME OFCOMPOUND


Aldehydes if the carbonylgroup is at the end of thecarbon skeleton

A ketone and analdehyde may bestructural isomers

with different properties,as is the case for

acetone and propanal.

Acetone

Propanal

Ketone and aldehydegroups are also foundin sugars, giving riseto two major groupsof sugars: ketoses

(containing ketone

groups) and aldoses(containing aldehydegroups).

Carboxyl

STRUCTURE

EXAMPLE

Carboxylic acids, or organic

acids

NAME OFCOMPOUND


Acetic acid

Acts as an acid; candonate an H+because the

covalent bond between

oxygen and hydrogen is so

polar:

Found in cells in the ionizedform with a charge of 1 and

called a carboxylate ion.

Nonionized Ionized

Figure 4.9c

Amino

Amines

Glycine

STRUCTURE

EXAMPLE Acts as a base; canpick up an H+from the

surrounding solution(water, in livingorganisms):

NAME OFCOMPOUND


Found in cells in theionized form with acharge of 1.

Nonionized Ionized

Figure 4.9d

Sulfhydryl

Thiols

(may bewritten HS)

STRUCTURE

EXAMPLE Two sulfhydryl groups canreact, forming a covalentbond. This cross-linkinghelps stabilize proteinstructure.

NAME OFCOMPOUND


Cross-linking of cysteinesin hair proteins maintainsthe curliness or straightnessof hair.

Cysteine

Figure 4.9e


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Figure 4.9f

Phosphate

STRUCTURE

EXAMPLE

NAME OFCOMPOUND


Organic phosphates

Glycerol phosphate

Contributes negativecharge to the moleculeof which it is a part(2 when at the end ofa molecule, as at left;1 when locatedinternally in a chain ofphosphates).

Molecules containingphosphate groups havethe potential to reactwith water, releasingenergy.

Figure 4.9g

Methyl

STRUCTURE

EXAMPLE

NAME OFCOMPOUND


Methylated compounds

5-Methyl cytidine

Addition of a methyl groupto DNA, or to moleculesbound to DNA, affects theexpression of genes.

Arrangement of methylgroups in male and femalesex hormones affects theirshape and function.

Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings

The Chemical Elements of Life:A Review

The versatility of carbon valence of four single and double bonds (even triple bonds) can bond with C, H, O, N, S can form long chains of atoms and produce

huge molecules (DNA, proteins)

Makes possible the great diversity of organicmolecules

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