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1
Molecules of Life
Chapter 22
Great Idea:A cell’s major parts are constructed from a few simple molecular building
blocks
2
Chapter Outline
• Organic Molecules• Organic Chemistry• Proteins: The Workhorses of Life• Carbohydrates• Lipids• Minerals and Vitamins
3
Organic Molecules
4
Four Basic Characteristics
• Most molecules based on chemistry of carbon– Organic molecules
• Life’s molecules form from few elements– H, O, C, N 97.5% of body weight
• Molecules composed of simple building blocks– Arranged differently
• Shape determines behavior– Determines ability for bonding
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Chemical Shorthand
• No H atoms or bonds to H are shown• C atoms are not shown explicitly
Shorthand
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iClicker Question
• Most molecules in living systems are based on the chemistry of:
– A nitrogen– B carbon– C phosphorus– D sodium
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iClicker Question
• Which four elements comprise 97.5% of our bodies’ weight?
– A P, S, Ca and Mg– B Fe, H, O, Na– C H, O, C, N
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9
Remember Abundance of Elements in Solar System
Relative Abundance of Elements in the Sun
0
2
4
6
8
10
12
0 5 10 15 20 25 30 35 40 45
Atomic Number
Log
of R
elat
ive
Abu
ndan
ce
H
He
Li
Be B
C
C
N
O
Fe
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
K
Ca
Fe
10
• C is a special case
• Valence electrons for C are four (one in each orbit of the 2nd shell)
• C – C: single covalent bond (one orbit; two atoms)
• C – C – C: two covalent bonds; two orbits; three atoms
Recall Covalent Bonds and Carbon
C - CC
C – C – C
C
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Principles of Carbon Chemistry: Functional Groups
• Features of C macromolecules–Carbon skeleton (chains, branches, rings)–Groups of atoms attached to carbon
skeleton - functional groups• Hydroxyl (OH)• Amino (NH2)• Phosphate (P)
C
C – C – OH
C
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Principle of Polymers
• Small molecules joined together to form large molecules up to 1,000’s of carbon atoms (macromolecules)
• Array of combinations, each with its own unique chemistry
• Principle of hierarchy theory and emergent properties
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Simple to Complex Polymers of Carbon
Methane - 1 C atom Ethane – 2 C atoms
Fullerene – 60 + C atoms (Buckyballs)
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Complex Carbon Polymers
aspirin
caffeinenicotene
Taxol – chemotherapy drug
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Hierarchy Theory and Emergent Properties
Number of macromolecules, each with its own chemistry
Carbon Skeletons
(e.g., branch, chains, etc.
Functional Groups (e.g., OH, NH2, etc.)
Carbon Atoms
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Principle of Polymers
• In living systems, polymers of carbon result in four major classes of macromolecules –Carbohydrates–Proteins–Nucleic acids–Lipids
• Potential diversity of carbon polymers
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Hydrocarbons
• Carbon compounds with only two elements (carbon and hydrogen)
• Most simple compound: methane (CH4)
H|
H – C – H|H
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Hydrocarbons: C to C Bonding
• C to C bond can be single bond (C-C)
Ethane
• C to C bond can be double bond (C = C)
Ethene or ethylene
• C to C bond can be triple bond (C = C)
Ethyne
• Saturated/unsaturated
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Hydrocarbons• Alkanes (C – C bonds only)
– Methane (C1H4) Natural gas– Ethane (C2H6)– Propane (C3H8) Propane gas– Butane (C4H10)– Pentane (C5H12)– Octane (C8H18) Gasoline– Decane (C10H22)– Pattern: CnH2n + 2)
• Triple bond (C = C)• Double bond (C = C)• Aromatics (cyclic C atoms/aromatics)
– C6H6
21
Aromatic Hydrocarbons
22
Question
There are millions of organic compounds but only a few thousand inorganic compounds because ____?
A. Organic compounds are formed by living critters
B. There is more C on the Earth’s surface than most other elements
C. Atoms of elements other than C never combine with themselves
D. C atoms combine with up to four other atoms, including other C atoms
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Functionality of Hydrocarbons
• Carbon skeleton
• Functional groups (e.g., OH)
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Organic and Biochemistry
• Keys:– Structure of basic unit (monomer)– Polymer structure (macromolecule)– Functional group (e.g., OH, PO3 or NH2)
• Types of carbon polymers in living systems– Carbohydrates– Lipids– Proteins– Nucleic acids
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Biochemistry
• Carbohydrates– Monomer: monosaccharide (glucose or C6H12O6)– Polymer: polysaccharide– Functional unit: hydroxyl or OH-
• Proteins– Monomer: amino acid (peptide)– Polymer: polypeptide and protein– Functional unit: amine or NH2
• Nucleic Acids– Monomer: nucleotide – Polymer: polynucleotide - DNA (deoxyribonucleic acid) and RNA
(ribonucleic acid)– Functional units: organic N base, carbohydrate, and phosphate
• Lipids– Monomer: fatty acid + glycerol unit– Polymer: fats, phospholipids and steroids– Functional unit: glycerol (3 OH- groups)
26
iClicker Question
Fatty acids and glycerols are part of • A Carbohydrates• B Proteins• C Nucleic Acids• D Lipids
27
iClicker Question
• The monomer “monosaccharide” is what type of molecular polymer?
• A Carbohydrate• B Protein• C Nucleic Acid• D Lipid
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iClicker Question
Amino acids are portions of• A Carbohydrates• B Proteins• C Nucleic Acids• D Lipids
29
iClicker Question
Nucleotides are portions of• A Carbohydrate• B Protein• C Nucleic Acid• D Lipid
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Carbohydrates
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Carbohydrates
• Structure– C, H, O
• Simplest– Sugars – CnH2nOn
• Monosaccharides• Polysaccharide• Starches• Cellulose
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CarbohydratesKeysKeys
Monosaccharide or Glucose (CMonosaccharide or Glucose (C66HH1212OO66))Functional unit: hydroxyl or OHFunctional unit: hydroxyl or OH--
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Monosaccharides
35
Polysaccharide: Glycogen
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iClicker Question
• True or False: Starch and cellulose are both polymers of glucose.
– A True– B False
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iClicker Question
• Individual sugar molecules are called:
– A glucoses– B starches– C monosaccharides
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iClicker Question
• The general chemical formula for sugar is:
– A NaCl– B CnH2nOn
– C CnH2n+2
– D C20H38S2N4
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Proteins: The Workhorses of Life
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Amino Acids: The Building Blocks of Proteins
• Amino Acid–Carboxyl group–Amino group–Carbon atom–Side group
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Amino Acids: The Building Blocks of Proteins
• Side Group–Makes amino acid unique
42
Amino Acids cont.
• Bonding– Two amino acids
• H bonds with OH • Forms H2O • Forms peptide bond
– Polypeptide• chain
• Protein– Large molecule– Chain of amino acids
• Only 20 amino acids in living organisms
43
The Structure of Proteins
44
Enzymes (protein catalysts)
• Enzymes–Specific shape & structure–Facilitates bonding
45
Enzymes
46
How Most Drugs Work
• Blocking enzymes–Block active site–Molecules cannot bond–Reaction does not take
place• Shape of molecules
–Block membrane transport
–Block neurotransmitters
47
Proteins
KeysAmino acid (monomer)Polypeptide (polymer)Functional unit: amine
or NH2
Polypeptide bond
serine – lysine – arginine – tryptophan – glutamic acid – etc.
48
Proteins: Linear Structure
49
Proteins: Linear Structure
50
Protein Conformation (1 and 2nd)
51
Protein Conformation (3rd & 4rd)
52
53
54
iClicker Question
• Proteins are made up of strings of basic building blocks called:
– A amino acids– B monosaccharides– C nucleotides
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iClicker Question
• How many different amino acids appear in the proteins of living systems on Earth?
– A 10– B 20– C 50– D 200
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iClicker Question
• The exact sequence of amino acids that go into a protein is called its:
– A primary structure– B secondary structure– C tertiary structure– D quaternary structure
57
iClicker Question
• In general, meat and dairy products supply low-quality proteins, while plant product supply high-quality proteins.
– A True– B False
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iClicker Question
• Of the 20 amino acids, how many are “essential amino acids” for human adults?
– A 8– B 12– C 17– D 20
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iClicker Question
• Shapes taken by the string of amino acids of a protein, such as a long helix or a sphere, are called its:
– A primary structure– B secondary structure– C tertiary structure– D quaternary structure
60
iClicker Question
• Silk, hair, and fingernails are made of:
– A proteins– B lipids– C carbohydrates
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Nucleic AcidsKeys
Nucleotides Functional units: organic N base, carbohydrate, and
phosphate
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Nucleic Acids as Polymers:DNA Double Helix
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64
Lipids
65
Lipids
• Lipids– Insoluble in
water
• Role of lipids– Cell membranes– Store energy
• Phospholipids– Make up cell
membrane
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Saturated and Unsaturated Fats
• Saturated–C is fully bonded–Basis of
cholesterol
• Unsaturated–Monounsaturated–Polyunsaturated
• hydrogenation
67
Cell Membranes
• Cell membrane–Hydrophilic–Hydrophobic
68
Biochemistry: Lipids
KeysFatty acids C16-18
Functional unit: glycerol (3 OH- groups)
69
Saturated Fats
70
Unsaturated Fats
71
iClicker Question
Fatty acids and glycerols are part of • A Carbohydrates• B Proteins• C Nucleic Acids• D Lipids
72
iClicker Question
• Saturated fats have no double bonds.
– A True– B False
73
iClicker Question
• The monomer “monosaccharide” is what type of molecular polymer?
• A Carbohydrate• B Protein• C Nucleic Acid• D Lipid
74
iClicker Question
Amino acids are portions of• A Carbohydrates• B Proteins• C Nucleic Acids• D Lipids
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iClicker Question
Nucleotides are portions of• A Carbohydrate• B Protein• C Nucleic Acid• D Lipid
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Biochemistry Summary
• Carbohydrates– Monomer: monosaccharide (glucose or C6H12O6)– Polymer: polysaccharide– Functional unit: hydroxyl or OH-
• Proteins– Monomer: amino acid (peptide)– Polymer: polypeptide and protein– Functional unit: amine or NH2
• Nucleic Acids– Monomer: nucleotide – Polymer: polynucleotide - DNA (deoxyribonucleic acid) and RNA
(ribonucleic acid)– Functional units: organic N base, carbohydrate, and phosphate
• Lipids– Monomer: fatty acid + glycerol unit– Polymer: fats, phospholipids and steroids– Functional unit: glycerol (3 OH- groups)
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Carbon Metabolism
Biosynthesis (Anabolism)
CO2 + H2O + Energy CH2O + O2(light) (C - C Bonds)
Catabolism
CH2O + O2 CO2 + H2O + Energy(C - C Bonds) (heat + chemical
energy – ATP)
Key is the C-C covalent bonding, which in turn is determined by electrons in the valence state, which in turn is underpinned by energy of electrons in their respective shells (storage and processing of energy via the making and breaking of C-C bonds)
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Granola Bar and the Carbon Atom
The energy of a “granola bar” is a function of multiple excited electrons being kicked to a higher quantum level in a chlorophyll molecule; subsequently, that “potential energy” is snatched and stored chemically in acarbohydrate molecule. When you digest thecarbohydrate polymer and break the covalent bonds, the potential energy of the electron in an elevated state is released as heat/chemical energy in metabolism.
80
iClicker Question
The chemical reactivity of organic carbon compounds is a function of the reactivity of the ____.
A Carbon to carbon double bond (C = C)B Carbon to carbon triple bond (C = C)C Carbon to carbon single bond (C – C)D Functional groups bond to the carbon atomE Reactivity of the covalent bonds between
carbon atoms
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Hierarchy in Biochemistry
Protein
Polypeptide
Amino Acid
Carbon Skeleton +Amine group (NH2)
82
Minerals and Vitamins
83
Minerals
• Minerals–All chemical elements except C, H, N, O
• Example–Calcium
• 2% of weight
84
Vitamins
• Vitamins– Organic molecules– Must be taken in with food
• Except vitamin D
• Water soluble– Vitamins B & C
• Fat soluble– Vitamins A, D, E, & K
• Function– Assist enzymes
85
SUMMARY
• Carbon is unique in its chemistry• Unusual behavior of carbon results in an
huge array of simple to complex molecules• Life as we know it is hard to imagine without
carbon behaving as a polymer• The chemistry of carbon is a case study of
the principle of hierarchy theory and emergent properties
• Carbon metabolism is the “currency” by which energy is processed, stored and used
• Weak chemical bonds (covalent carbon bonds) play a critical role in the chemistry of life
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iClicker Question
• Which vitamins are water soluble?– A B and C– B A, D, E, and K– C F, G, and H
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iClicker Question
• The information in this chapter influences me in terms of eating a healthier diet.
– A True– B False