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Chemical Basis of Life
Outline: The Chemical Basis of Life
1. Chemistry of Carbon
2. Polymers & Monomers
3. Biologically Important Compounds Carbohydrates Lipids Proteins Nucleic Acids
ProtonsNeutronsElectrons
1. Carbon has 4 valence electrons
2. Each carbon atom four covalent bonds
Carbon Chemistry
Electron PairCovalent Bond
Covalent Bonds in Carbon
Carbon ChemistryMolecular Formula
CH4
C2H6
Carbon Chemistry
C4H10C4H10
C4H8 C4H8
Carbon Chemistry
Structuralformula
Methane
H H
H
H H H
H
H
Ball-and-stickmodel
Space-fillingmodel
C
C
The 4 single bonds of carbon point to the corners of a tetrahedron.
H H
HH
H H
Ethane Propane
HH
H H
H
H
H
H
H
H
Carbon skeletons vary in length.
H
H
H
H
H H
H H
H H
H H
H H
H H
H
H
H
H
H
H H H H
H
H
C
HH H
H H
H H
H
H
H
H H
H
H
HH
H
H
H H
H
H
Butane Isobutane
Skeletons may be unbranched or branched.
1-Butene 2-Butene
Skeletons may have double bonds, which can vary in location.
CC C
C
CC
H
CC
C
CC
C
Cyclohexane Benzene
Skeletons may be arranged in rings.
C C C C C
C C C C
C
C CC
CCC C CCCH H
Summary: Carbon Chemistry
4 Covalent Bonds
Variable Length
Unbranched or Branched
Single or Double Bonds
Rings
Functional Group
StructuralFormula
HS
P
O–
O
O
HC
H
H
OH
O
OHC
H
HN
CO
C
H
H
CH
H
H
OH
CH
H
HC
O
OH
H
CH3
OH
CCHO NH
CH
H
HHC
O
CHOH
H HS HC
H
CH
OH
HC
OH
H HOC
H
P
O
C
O
C
O
HHC
H
O–
O–
O–
O–
FUNCTIONAL GROUPS Hydroxyl
Carbonyl
Carboxyl
Amino
Sulfhydryl
Phosphate
Methyl
HYDROXYL
Carboxyl
Melting Point (C)
C2H6O -114
C2H5O2 17
C2H6O 78
Boiling Point (C)
C2H5O2 118
Figure 3. Functional groups of male and female sex hormones
Male lion
Female lion
Estradiol
HO
OH
OH
OTestosterone
H
OH HOH
H OH
Unlinked monomer
Dehydration reaction
Longer polymer
Short polymer
H2O
Dehydration synthesis isPolymer Building
H
H2O
OH
H OHOH H
Hydrolysis
Hydrolysis is Polymer Breaking
Classes of Biologically Important Compounds
CarbohydratesLipidsProteinsNucleic Acids
Carbohydrates
Monosaccharides
Disaccharides
Polysaccharides
Figure 3.4B Structure of Monosaccharides
C
C
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H H
H
H
H
HO
H
H
H
C
O
HO
OH
OH
OH
OH OH
OH
OH
C O
OH
Glucose Fructose
C6H12O6
CarbonylGroup
CarboxylGroups
Three representations of glucose
H
H
H
H
H
H H
H
H HO
C
C
C C
O
OHOH HO OH
OH
CH2OHCH2OH
C
OH
OH
O
OH
Structural formula
Abbreviated structure
Simplified structure
6
5
4
3 2
1
6
5
4
3 2
1
Figure 3.5 Disaccharide formation
H
HH
H
H HO
H
H
H
H
H
H
H
H
H HH
H
H
H
OH OH
OHOHOH
HO
O O
O
OH
OH
OH
CH2OH CH2OH
CH2OH CH2OH
H2O
OH
HO
O
OH
H
Glucose Glucose
Maltose
O
OH
Lactose – A Disaccharide
OH
OH
H
H
H
HH
OH
OH
OH
O
H
H
O
H
H
H
OH
O
Galactose
Glucose
CH2OH
CH2OH
Starch
Glycogen
Cellulose
Starch in potato cells
Glycogen in muscle tissue
plant cell wall
Glucose monomer
Cellulose molecules
STARCH
GLYCOGEN
CELLULOSE
O O
OOOOOO
O O O
O
OO
OO
OO
OOOO
OO
OOO
OO
OOOO O
OOOOOO
OOOOOO
O
OH
OH
Figure 3.7
Polysaccharides – Complex Carbohydrates
Functions of Carbohydrates
1. Energy Source e.g. blood sugar
2. Energy Storage e.g. starch
3. Structural Material e.g. cellulose
End Carbohydrates
Start Fri 9/15/06
Classes of Biologically Important Compounds
CarbohydratesLipidsProteinsNucleic Acids
Lipids
Properties
Non-polar molecules
Not Water soluble
Dissolve in nonpolar solvents
1. Fatty acids
2. Triglycerides or neutral fats
3. Phospholipids
4. Steroids, prostaglandins and waxes
Types of Lipids
Fatty Acid Structure
Hydrocarbon chain CarboxylGroup
Saturated & Unsaturated Fatty Acids
Cis & Trans Unsaturated Fatty Acids
Increase LDL levels (bad cholesterol)
Decrease HDL levels (good cholesterol)
Increase heart attack risk
Trans Fatty Acids
Omega Numbering System for Fatty Acids
Linoleic Acid
An omega-6 fatty acid
Unsaturated Fatty Acids
1. Monounsaturated and Polyunsaturated fatty acidsMONO ONE double bondPOLY more than one double bond
2. Essential fatty acids – All unsaturatedA. linoleic acid… Omega-6 fatty acid
sources: canola, soybean, corn, flaxseed1. heart protective
B. alpha linolenic acid … Omega-3 fatty acidsources: canola, olive oil, flax seed oil1. heart protective2. Reduce triglycerides
Beneficial Fatty Acids
1. Saturated
2. UnsaturatedA. monounsaturatedB. polyunsaturated
Types of polyunsaturated fatty acids1. omega-3 alpha linolenic acid2. omega-6 linoleic acid
3. Trans fatty acids...products of food processing
Fatty Acids - Summary
Triglyceride Synthesis
Triglyceride or Neutral Fat
Structure of a Triglyceride
C
C
C
Fatty acid
Fatty acid
Fatty acid
H
H
H
H
H
Hydrophilic Polar Head
HydrophobicNonpolar Tails
Phospholipid Structure
Phospholipid bilayer Water
Membrane Structure
Steroids
HydrocortisoneCholesterol
Digitoxin
Steroids
Other Lipids
Waxes
Citronellol Taxol
Terpenes
Prostaglandins
Waxes, Sperm Whales & Jojoba oil
Examples of Waxes, Terpenes and Prostaglandins
WaxesJojoba oilBeeswaxCarnauba wax
TerpenesCitronellolTaxolMentholCamphor oil
ProstaglandinsThromboxane – stimulates blood clottingPGE2 – stimulates uterine contractions/laborInflammation/painControl of blood pressure
Lipid Functions
1. Long term energy storageTriglycerides
1. ProtectionFat deposits around kidneysProstaglandin thromboxane induces clottingWaxes on leaf surface
2. Synthesis: hormonesCholesterol
Classes of Biologically Important Compounds
CarbohydratesLipidsProteinsNucleic Acids
Fig. 3.4
H
N
C
O
OH
Aminogroup
Carboxyl group
Protein Structure
CR
H H
Protein = chain of amino acids
Amino acid
H
H N C OH
H
H
H2O
H C OH
O
C
Amino acidAmino acid
H
H N C
H
H
C OH
O
C
Polypeptide chain
R R
R
O
C N
H
O
C N
H
R
Peptide Bond
Nonpolar Amino Acids
Amino Acid Structure
Amino Acid Structure
Polar Charged
Amino Acid Structure
Amino Acid Structure
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Proline(Pro)
CH C
NH2+ O
Methionine(Met)
CH2
C C O–
H O
CH2
S
CH3
Cysteine(Cys)
H3N+ C C O–
H O
SH
Special Function Amino Acids
CH2
CH2CH2
CH2
H3N+
O–
Types of Amino Acid Side Groups - Summary
1. Non-Polar
2. Polar – Uncharged
3. Polar – Charged
4. Aromatic
5. Special Function
Four Levels of Protein Structure
Primary
Secondary
Tertiary
Quaternary
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Protein StructureLevels of Protein Structure
Primary structureGly
ThrGly Glu
Ser Lys
Cys
ProLeu Met
Val
Lys
ValLeu Asp Ala Val Arg Gly Ser
Pro
Ala
Ile
Asn ValAla
ValHis Val
Secondary structureC
N
O C
C
N H
O C
C
HC
N HC
CO
N H
O C
C
N H
C
N
O C
C
N HO C
C
N H
CO
C
H
N H
CO
H C R
HN
Alpha helix
Amino acids
CN
H
C C
H HO
NR C C
ON
H
O
C C N
H
C C
O
N
H
O
C C NH
C
O
C N
H
O
C C N
H
C
O
O
CC
N
H
C C
O
N
H
C C
O
N
H
CC
O
N
H
CC
O
N
H
C C
O
N
H
CC
O
N
H
CC
O
H
N
C
Pleated sheet
Tertiary structure
Quaternary structure
PheArg
Animation07F1005ProteinPrimaryStructureCampbelletal.swf
Animation08F1005ProteinSecondaryStructureCampbelletal.swf
Animation09F1005ProteinTertiaryStructureCampbelletal.swf
Animation10F1005ProteinQuaternaryStructureCampbelletal.swf.swf
Domains
Two or morePolypeptides
What is it?
Humans: Creutzfeldt Jacob Disease
Cattle: Bovine Spongiform encephalopathy(Mad cow disease)
Deer: Chronic Wasting Disease
Normal (Good) PrPC43% -helix
Prion (Bad) PrPSc30% -helix43% -sheet
Normal Protein Folding is Critical to Function
Protein Functions
Function Class Examples Use
Enzyme catalysis
Enzymes ProteasesBreak down
protein
Defense Immunoglobulins AntibodiesMark foreign substances
TransportLong distance transporters
HemoglobinTransport O2
and CO2
TransportShort distance transporters
Proton pumpTransports
protons across membranes
Function Class Examples Use
Support Fibers CollagenForms
cartilage
Motion MuscleActin & Myosin
Muscle Contraction
Regulation
Hormones InsulinGlucose
Transport
Storage Ion BindingFerritin
Calmodulin
Stores IronBinds
Calcium
Protein Functions
Classes of Biologically Important Compounds
CarbohydratesLipidsProteinsNucleic Acids
Nucleic Acids
Deoxyribonucleic Acid = DNA
Genetic Material
Ribonucleic Acid = RNA
Protein Synthesis
Fig. 3.14(TE Art)
Phosphate group
Sugar
Nitrogenous base
N
N
O
P CH2
O
–O
O–
OH ROH in RNA
H in DNA
O
N
NH2
N
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
A Nucleotide is a monomer of a nucleic acid
Adenine
Guanine
CC
NN
N
C
HN
CCH
O
H
Cytosine(both DNAand RNA)
Thymine(DNA only)
Uracil(RNA only)
HCC
NC
HN
C
NH2
N
NCH
OCC
NC
HN
CH
H
OCC
NC
HN
C
O
HH3CH
OCC
NC
H
N
C
O
HHH
PURINES
PYRIMIDINES
NH2
NH2
Fig. 3.16(TE Art)
Sugar-phosphate "backbone"
Hydrogen bonds betweennitrogenous bases
Phosphodiesterbond
P
P
P
P
P
P
P
P
C
C
G
G
A
A
T
T
P
O
O
O
O
O
O
O
O
O
OO
C G
5’ end
3’ endOH
P
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
DNA Structure
Fig. 3.17b(TE Art)
RNA Structure
Ribose-phosphatebackbone
Bases
G
G
C
A
A
U
U
P
P
PP
P
P
P
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nucleic Acid Functions
DNA – Genetic material
RNA – Protein synthesis
END
Fig. 3.13
END
Carbohydrates
Lipids
Proteins
Nucleic Acids