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• Chapter 4~Carbon & The Molecular Diversity of Life
• Chapter 5~ The Structure & Function of
Macromolecules
Organic chemistryOrganic chemistry
• Biological thought:
• Vitalism (life force outside physical & chemical laws) – organic compounds can only arise in living organisms - Berzelius
• Mechanism (all natural phenomena are governed by physical & chemical laws) – organic compounds may be produced in lab - Miller
• Carbon
– Ability to branch in 4 directions allows large molecules possible
– Tetravalence, tetrahedron
– Shape determines function
HydrocarbonsHydrocarbons
• Only carbon & hydrogen (petroleum; lipid ‘tails’)
• Covalent bonding; nonpolar
• High energy storage
• Isomers (same molecular formula, but different structure & properties)
– 1. Structural~differing covalent bonding arrangement
– 2. Geometric~differing spatial arrangement
– 3. Enantiomers~mirror images pharmacological industry (thalidomide)
Functional Groups, IFunctional Groups, I
• Attachments that replace one or more of the hydrogens bonded to the carbon skeleton of the hydrocarbon
• Each has a unique property from one organic to another
• 1. Hydroxyl Group– H bonded to O (-OH);
alcohols; polar (oxygen);solubility in water
• 2. Carbonyl Group– C double bond to O– At end of C skeleton -
aldehyde - ex. proponal– Within C skeleton – ketone –
ex. acetone
Functional Groups, IIFunctional Groups, II
• 3. Carboxyl Group– O double bonded to C to hydroxyl– carboxylic acids, organic acids– covalent bond between
O and H is very polar leads to dissociation,
H ion
• 4. Amino Group – N to 2 H atoms (-NH2)– Amines– acts as a base
• 5. Sulfhydral Group– sulfur bonded to H
– thiols
• 6. Phosphate Group– phosphate ion covalently
attached by 1 of its O to the C skeleton
– transfer energy
PolymersPolymers
• Macromolecules – may have thousands of linked molecules
• Poly = many; mers = parts• Covalent monomers link to form
polymers• Condensation reaction (dehydration
reaction):– One monomer provides a
hydroxyl group while the other provides a hydrogen to form a water molecule
– Forms polymers• Hydrolysis: bonds between
monomers are broken by adding water (digestion) – aided by enzymes
Carbohydrates, ICarbohydrates, I
• Monosaccharides – CH2O (1:2:1) formula – Multiple hydroxyl (-OH) groups
and 1 carbonyl (C=O) group– Location determines if aldehyde
(aldose) sugar or ketone (ketose) sugar
– Cellular respiration breaks them down
– Raw material for amino acids and fatty acids
– Ex. Glucose, fructose
Carbohydrates, IICarbohydrates, II
• Disaccharides
– Glycosidic linkage (covalent bond) between 2 monosaccharides
– No longer have 1:2:1 multiples – water is pulled out (condensation/ dehydration reaction)
– Sucrose (table sugar) -most common disaccharide
Carbohydrates, IIICarbohydrates, III
• Polysaccharides Storage: Starch~ glucose monomers Plants: plastids Animals: glycogen
• Polysaccharides Structural: Cellulose~ most abundant
organic compound; Chitin~ exoskeletons; cell walls of fungi; surgical thread
Lipids, ILipids, I• Fats, phospholipids, steroids
• No polymers; glycerol and fatty acid
• Glycerol – alcohol w/ 3C each w/ hydroxyl group
• Fatty acid – long C chain w/ carboxyl group
• Non-polar C-H bonds in fatty acid ‘tails’
• Cause to be hydrophobic
• Ester linkage: 3 fatty acids to 1 glycerol (dehydration formation)
• Triacyglycerol (triglyceride)
• Saturated (solid) vs. unsaturated (liquid) fats; single vs. double bonds
Lipids, IILipids, II
• Phospholipids – 2 fatty acids instead of
3 – replaced by a phosphate group
– ‘Tails’ hydrophobic; ‘heads’ hydrophilic
– Micelle (phospholipid droplet in water)
– Form a bilayer (double layer) - cell membranes
Lipids, IIILipids, III
• Steroids
– Lipids with 4 fused carbon rings
– Ex: cholesterol:
• Cell membranes
• Precursor for other steroids (sex hormones – estrogen, testosterone)
• Too mcuh = atherosclerosis – narrowing of vessel walls
Proteins, IProteins, I
• Importance - instrumental in nearly everything organisms do; 50% dry weight of cells; most structurally sophisticated molecules known – enzymes, insulin, antibodies
• Monomer: amino acids (there are 20) – Contain a carboxyl (-COOH) group, amino group (NH2), H atom, variable
group (R – aka side chain – gives each its identity and properties)• Variable group characteristics: polar
(hydrophilic), nonpolar (hydrophobic), acid or base• Three-dimensional shape – conformation – determines function• Polypeptides (dehydration reaction)
– Joined by peptide bonds (covalent bond); carboxyl group to amino group (polar)
Proteins, IIProteins, II
• Primary Structure
– Conformation: Linear structure
– Molecular Biology: each type of protein has a unique primary structure of amino acids
– Ex: lysozyme
– Amino acid substitution: hemoglobin; sickle-cell anemia
Proteins, IIIProteins, III
• Secondary Structure– Conformation: coils &
folds (hydrogen bonds)– Alpha Helix: coiling;
keratin– Beta Pleated Sheet:
parallel; silk
Proteins, IVProteins, IV
• Tertiary Structure
– Conformation: irregular contortions from R group bonding
• hydrophobic
• disulfide bridges
• hydrogen bond
• ionic bonds
Proteins, VProteins, V
• Quaternary Structure
– Conformation: 2 or more polypeptide chains aggregated into 1 macromolecule
• collagen (connective tissue)
• hemoglobin
– Heat, pH, other body disturbances may denature protein (becomes inactive) – loses conformation
Nucleic Acids, INucleic Acids, I
• Deoxyribonucleic acid (DNA)
• Ribonucleic acid (RNA)
• DNA>RNA>protein
• Polymers of nucleotides (polynucleotide):
– nitrogenous base
– pentose – 5 carbon sugar
– phosphate group
• Nitrogenous bases:
– Pyrimidines – single ring ~cytosine, thymine (DNA), uracil (RNA)
– Purines – double ring~adenine, guanine
Nucleic Acids, IINucleic Acids, II
• Pentoses:– ribose (RNA)
– deoxyribose (DNA)
– nucleoside (base + sugar)
• Polynucleotide:– phosphodiester linkages (covalent) –
btw phosphate + sugar
Nucleic Acids, IIINucleic Acids, III
• Inheritance based on DNA replication
• Double helix (Watson & Crick - 1953)
– H bonds~ between paired bases
– van der Waals~ between stacked bases
• A to T; C to G pairing
• Complementary
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