lecture 2, ch. 4,5
TRANSCRIPT
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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