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Lecture #2Lecture #2 Date ______Date ______

Chapter 4~Carbon &

The Molecular

Diversity of Life

Chapter 5~The Structure &

Function of

Macromolecules

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Organic chemistryOrganic chemistry

Biological thought: Vitalism(life force outside physical &

chemical laws)Berzelius

Mechanism(all natural phenomenaare governed by physical & chemicallaws)Miller

Carbontetravalencetetrahedronshape determines function

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HydrocarbonsHydrocarbons

Only carbon & hydrogen(petroleum; lipid tails)

Covalent bonding; nonpolar

High energy storage Isomers(same molecular formula,

but different structure & properties)

structural~differing covalentbonding arrangement

geometric~differing spatialarrangement

enantiomers~mirror imagespharmacological industry(thalidomide)

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Functional Groups, IFunctional Groups, I

Attachments thatreplace one or more ofthe hydrogens bondedto the carbon skeletonof the hydrocarbon

Each has a uniqueproperty from oneorganic to another

Hydroxyl GroupH bonded to O;

alcohols;

polar (oxygen);solubility in water

Carbonyl Group Cdouble bond to O;

At end of HC: aldehydeOtherwise: ketone

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Functional Groups, IIFunctional Groups, II

Carboxyl Group O double bonded to C to hydroxyl;

carboxylic acids;

covalent bond betweenO and H;

polar; dissociation, H ion

Amino GroupN to 2 H atoms;

amines;

acts as a base (+1)

Sulfhydral Groupsulfur bonded to H;

thiols

Phosphate Groupphosphate ion;

covalently attached by 1 ofits O to the C skeleton;

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PolymersPolymers

Covalent monomers Condensation reaction

(dehydration reaction):

One monomer provides ahydroxyl group while the otherprovides a hydrogen to form awater molecule

Hydrolysis:bonds between monomers

are broken by adding water(digestion)

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Carbohydrates, ICarbohydrates, I

Monosaccharides CH2O formula; multiple hydroxyl (-OH)

groups and 1 carbonyl(C=O) group:aldehyde (aldoses) sugarketone sugar

cellular respiration; raw material for amino acids

and fatty acids

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Carbohydrates, IICarbohydrates, II

Disaccharides glycosidic linkage (covalent

bond) between 2

monosaccharides; covalent bond by dehydrationreaction

Sucrose (table sugar) most common disaccharide

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DisaccharidesDisaccharides

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Carbohydrates, IIICarbohydrates, III

PolysaccharidesStorage: Starch~ glucose monomers

Plants: plastids Animals:glycogen

PolysaccharidesStructural:

Cellulose~ most abundantorganic compound;

Chitin~ exoskeletons; cellwalls of fungi; surgical thread

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PolysaccharidesPolysaccharides

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LipidsLipids

No polymers; glycerol and fatty acid Fats, phospholipids, steroids Hydrophobic; H bonds in water exclude fats Carboxyl group = fatty acid

Non-polar C-H bonds in fatty acid tails Ester linkage: 3 fatty acids to 1 glycerol(dehydration formation)

Triacyglycerol (triglyceride) Saturated vs. unsaturated fats; single vs. double bonds

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Lipids, IILipids, II

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SteroidsSteroids

Lipids with 4 fused carbon rings

Ex: cholesterol:cell membranes;

precursor for othersteroids (sex hormones);

atherosclerosis

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ProteinsProteins

Importance:instrumental in nearly everything organisms do; 50% dry weight of cells; moststructurally sophisticated molecules known

Monomer: amino acids (there are 20) ~ carboxyl (-COOH) group, amino group (NH2), H atom, variable group (R).

Variable group characteristics:polar (hydrophilic), nonpolar (hydrophobic), acid or base

Three-dimensional shape (conformation)

Polypeptides (dehydration reaction):peptide bonds~ covalent bond; carboxyl group to amino group (polar)

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Primary StructurePrimary Structure

Conformation:Linear structure

Molecular Biology:each type of protein has a unique primarystructure of amino acids

Ex: lysozyme Amino acid substitution:

hemoglobin; sickle-cell anemia

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Secondary StructureSecondary Structure

Conformation:coils & folds (hydrogen bonds)

Alpha Helix:

coiling; keratin Pleated Sheet:

parallel;silk

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Tertiary StructureTertiary Structure

Conformation:irregular contortions fromR group bondinghydrophobicdisulfide bridgeshydrogen bonds

ionic bonds

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Quaternary StructureQuaternary Structure

Conformation:2 or more polypeptidechains aggregated into 1

macromoleculecollagen (connectivetissue)

hemoglobin

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Nucleic Acids, INucleic Acids, I

Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) DNA->RNA->protein

Polymers of nucleotides(polynucleotide):

nitrogenous basepentose sugarphosphate group

Nitrogenous bases:pyrimidines~cytosine, thymine, uracilpurines~adenine, guanine

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Nucleic Acids, IINucleic Acids, II

Pentoses:ribose (RNA)deoxyribose (DNA)

nucleoside(base + sugar) Polynucleotide:

phosphodiester linkages(covalent); phosphate + sugar

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Nucleic Acids, IIINucleic Acids, III

Inheritance based on DNAreplication

Double helix (Watson & Crick

- 1953) H bonds~ between paired basesvan der Waals~ between stacked

bases

A to T; C to G pairing Complementary