Download Biological Molecules Biological molecules consist primarily of

Outline: The Chemical Building Blocks of Life
1. Chemistry of Carbon
2. Polymers & Monomers
3. Biologically Important Compounds
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™
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Carbohydrates
Lipids
Proteins
Nucleic Acids
Biological Molecules
Biological molecules consist primarily of
-carbon bonded to carbon, or
-carbon bonded to other molecules.
Carbon can form up to 4 covalent bonds.
Carbon may be bonded to functional
groups with specific properties.
2
Carbon Chemistry
Protons
Neutrons
Electrons
Covalent Bonds in Carbon
Electron Pair
Covalent Bond
1. Carbon has 4 valence electrons
2. Each carbon atom Æ four covalent bonds
1
Carbon Chemistry
Carbon Chemistry
Molecular
Formula
C4H10
C4H10
CH4
C2H6
C4H8
C4H8
Carbon Chemistry
Carbon Chemistry
2
Structural
formula
Summary: Carbon Chemistry
H
4 Covalent Bonds
Space-filling
model
Ball-and-stick
model
H
H
C
H
H
Methane
H
H
C
C
H
H
H
H
H
H
H
C
C
C
H
H
H
Ethane
HYDROXYL
OH
H C C OH
H H
Carbonyl
C
O
H O
H C C H
H
H
Propane
Carboxyl
C
OH
H
Unbranched or Branched
H
H
H
C
C
H
H
H
H
C
C
H
H
H
H
H
H
H
C
C
H
H
C
Amino
H
Isobutane
H
H
H
H
C
C
C
C
H
H
Single or Double Bonds
H
H
H
H
H
H
C
C
C
C
H
H
Sulfhydryl
H
S H
H
1-Butene
2-Butene
Skeletons may have double bonds, which can vary in location.
O
Phosphate
H
H
Rings
N
Carboxyl
H
Skeletons may be unbranched or branched.
H
H
H
H
C
H
C
C
C
H
C
H
H
H
H
H
H
C
H
Cyclohexane
C
C
C
H
HC
C2H6O -114
O
C
H
Melting
Point (C)
OH
C2H5O2
17
H
C
Butane
H
O
Carbon skeletons vary in length.
H
H H
Hydroxyl
H
H
The 4 single bonds of carbon point to the corners of a tetrahedron.
H
Structural
Formula
Functional
Group
C
H
Variable Length
FUNCTIONAL
GROUPS
C
C
C
–
–
O P OH
O
H
H
H
C H
H
Methyl
H
Benzene
Skeletons may be arranged in rings.
O H
H
HO C C N
CH3 H
H H
HO C C S H
H H
OH OH H
O
Boiling
Point (C)
C2H6O
78
C2H5O2
118
C C C O P O–
H H H
O–
O O H
O– C C C H
H
Dehydration synthesis is
Polymer Building
Importance of Functional Groups
Unlinked monomer
H
A
B
C
D
OH
H
Short polymer
A
B
C
D
OH
H2O
Dehydration
reaction
H
E
E
OH
Longer polymer
3
Classes of Biologically Important Compounds
Hydrolysis is Polymer Breaking
™Carbohydrates
™Lipids
™Proteins
™Nucleic Acids
H2O
OH
H
Hydrolysis
H
OH
H
OH
Structure of Monosaccharides
Carbohydrates
O
H
C6H12O6
C
Molecules
• 1:2:1 ratio of carbon, hydrogen, oxygen
empirical formula: (CH2O)n
• examples: sugars, starch, glucose
• C – H covalent bonds hold much energy
• good energy storage molecules
C
OH
HO
C
H
H
C
OH
H
C
OH
H
C
OH
H
C
OH
C
O
HO
C
H
H
C
OH
H
C
OH
H
C
OH
H
H
Glucose
H
Carbonyl
Group
Hydroxyl
Groups
H
Fructose
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4
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Carbohydrates
Monosaccharide Structure
C6H12O6
H
3-carbon C
1
sugar
5-carbon sugars
O
5 CH2OH
5 CH2OH
O
H C OH
2
H C OH
3
H
O
OH
1
H
H
2
OH H
Deoxyribose
OH
1
4 H
H H
H
3
2
OH OH
Ribose
Glyceraldehyde
4
H
H3
6-carbon sugars
H5 H
4 OH
HO3
17
6 CH2OH
5
OH
OH
1
4 H
OH H
H
H
2
3
H OH
Galactose
6 CH2OH
6 CH2OH
O H
1
H OH
2
OH
H
Glucose
O
H
5
H HO 2
CH2OH
HO
3 1
4
OH H
Fructose
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Polysaccharides – Complex Carbohydrates
Carbohydrates - Disaccharides
CH2OH
O H
H
H
1
4
OH H
OH
HO
H
OH
CH2OH
CH2OH
CH2OH
CH2OH
O H H
O H H
O H H
O H
H H
H
H
14 H
OH H O OH H O OH H O OH H
α form of glucose
-2 monosaccharides linked together by
dehydration synthesis
-used for sugar transport or energy
storage
-examples: sucrose, lactose, maltose
H
OH
H
OH
H
OH
H
Cellulose
Plant
cell wall
CH2OH
H H O OH
1
4 OH
H
HO
H
H OH
19
β form of glucose
OH
Starch: chain of α-glucose subunits
Starch
O
OH H O
H H
OH O
CH2OH
H
O
H OH H
O
CH2OH
H
H
H H H CH2OH
H
O
H
OH
O
H
O
OH
O
OH H 14
H
H
CH2OH
H OH
Glycogen
Cellulose: chain of β- glucose subunits
5
Carbohydrates
Lipids
Polysaccharides
-long chains of sugars
-used for energy storage
-plants use starch; animals use glycogen
-used for structural support
-plants use cellulose; animals use chitin
™Properties
ƒNon-polar molecules
ƒNot Water soluble
ƒDissolve in nonpolar solvents
21
Types of Lipids
1. Fatty acids
2. Triglycerides or neutral fats
3. Phospholipids
4. Steroids, prostaglandins and waxes
Lipids
Fatty acids are long hydrocarbon chains
which may be
-saturated
-unsaturated
-polyunsaturated
Triglycerides (fats)
-composed of 1 glycerol + 3 fatty acids
24
6
Saturated & Unsaturated Fatty Acids
Fatty Acid Structure
Hydrocarbon chain
Carboxyl
Group
Cis & Trans Unsaturated Fatty Acids
Structure of a Triglyceride
Glycerol
H
H
H C
OH
H C
Fatty acid
H C
OH
H C
Fatty acid
H C
OH
H C
Fatty acid
H
H
7
Triglycerides or Neutral Fats
Lipids
Triglycerides
excellent molecule for energy storage
twice as much energy as carbohydrates
animal fats
usually saturated
solid at room temperature
plant fats (oils)
usually unsaturated
liquid at room temperature
30
Phospholipid Structure
Membrane Structure
Hydrophilic
Polar Head
Hydrophobic
Nonpolar Tails
Phospholipid bilayer
Water
8
Steroids
Cholesterol
Steroids
Digitoxin
Hydrocortisone
Lipid Functions
Other Lipids
1. Long term energy storage
Triglycerides
Waxes
1. Protection
Terpenes
Citronellol
Taxol
Prostaglandins
Fat deposits around kidneys
Prostaglandin (thromboxane) induces clotting &
inflammation response
Waxes on leaf surface
2. Synthesis: hormones
Cholesterol
9
Proteins
Classes of Biologically Important Compounds
Enzyme
catalysts
Support
Motion
Defense
Proteins
Regulation insulin
Transport
Calcium
storage
38
Amino Acid Structure
Proteins
Carboxyl Group
Proteins are polymers of amino acids.
Amino acids
-20 different amino acids
-joined by dehydration synthesis
-peptide bonds connect amino acids
Amino Group
39
10
Amino Acid Structure
Nonpolar Amino Acids
Amino Acid Structure
Polar Charged
Amino Acid Structure
Polar Uncharged
Amino Acid Structure
Aromatic
11
Protein Synthesis
Proteins Have Four Levels of Organization
• Primary
• Secondary
• Tertiary
• Quaternary
..\
Secondary Protein Structure
Primary Protein Structure
Chain of amino acids
1
R
H H O
R
H H O
R
H H
C C N C C N C C N C C N C C N C
H O
H H O
H H O
R
R
R
Tensile strength e.g. silk
Flexible e.g. wool
12
Tertiary Protein Structure
1.
2.
3.
4.
Tertiary Structure:
Domains
structural regions within a larger protein
folds into stable areas
Modular units of 100 to 250 amino acids
Domains are functional regions of a protein
Bonds Stabilize Protein Structure
1. Hydrogen Bond
2. Disulfide bridge
3. Ionic bond
4. Van der Waals attraction
Proteins
Denaturation is a change in the shape of a
protein, usually causing loss of function.
-may involve complete unfolding
-caused by changes in the protein’s
environment
-pH
-temperature
-salt concentration
5. Hydrophobic Exclusion
52
13
Normal Protein Folding is Critical to Function
Normal (Good) PrPC
43% α-helix
Mistake in tertiary protein structure
Prion (Bad) PrPSc
30% α-helix
43% β-sheet
Creutzfeldt Jacob Disease
Chronic Wasting Disease
Bovine Spongiform encephalopathy
(Mad Cow Disease)
Fig. 3.8h(TE Art)
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Quaternary Protein
Structure
Protein Structure
Primary
Secondary
Secondary
Tertiary
Quaternary
56
14
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Fig. 3.14(TE Art)
Nucleic Acids
¾ Nucleic Acid = polymer of nucleotides
¾ Types of Nucleic Acids
¾ Deoxyribonucleic Acid = DNA
ƒ Genetic material
A Nucleotide is a
monomer of a
nucleic acid
Nitrogenous base
NH2
N
N
Phosphate group
O
P O CH2
O–
O
¾ Ribonucleic Acid = RNA
ƒ Protein synthesis
OH in RNA
OH
R
Sugar
Nitrogen Bases of Nucleic Acids
N
N
O
–
H in DNA
Nucleic Acid Structure
15
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Fig. 3.16(TE Art)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
DNA Structure
Double Helix
RNA Structure
P
C
G
O
C
P
Paired Nitrogen
P
Bases
C
P
U
P
OH
3’ end
A
P
A
Nitrogenous
Bases
P
G
Phosphate
P
Nucleotide
T
P
G
U
P
A
T
Ribose (sugar)
C
A
P
G
P
P
Hydrogen bonds
P
P
P
Sugar-phosphate
"backbone"
P
G
5’ end
Adenosine Triphosphate Nitrogenous base
(adenine)
ATP
NH2
N
Triphosphate group
O
–
O P
O
–
O
P
O
–
N
O
O
O
P
O
N
O CH2
N
–
O
OH OH
5-carbon sugar
16