Download Chapter 4 - Organic Chemistry

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• Draw an atom of oxygen
• Draw two atoms of hydrogen bonded to
one atom of oxygen
• What type of bond do O and H form?
• What is a covalent bond?
• What is an ionic bond?
• What is an isotope?
Chapter 4
Organic Chemistry
4-1 Water
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75% of earth’s surface
Most abundant compound in living things
Liquid at room temperature
Expands when freezes
– Necessary for life
• Charged molecule – polar
• E- unevenly distributed
• “little magnet”
• Polarity allows water to stick to others
and go in between other molecules
Water Molecule
• Cohension – water sticking to water
• Adhesion – water sticking to other things
Hydrogen Bonding
Mixtures
• Substances are physically mixed but have
not formed new chemical bonds
• Different substances in a mixture retain
their usual properties
• Ex. Table salt and iron filings, sugar and
sand
• Homogeneous – spread evenly
throughout
Solutions
• Solutions - Mixtures that are liquid
• Solvent - the liquid substance that makes
up the bulk of the solution
• Water is the universal solvent.
• Solute – other substances that are
dissolved in the solvent
• Concentration – the measurement of the
amount of solute dissolved in a fixed
amount of solution
• Aqueous solutions – solutions in which
water is the solvent
Solutions
• When ionically bonded compounds dissolved in
water they dissociate or break apart into
individual ions
• NaCl  Na+ + Cl• HCl  H+ + Cl-
H+
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Most chemically reactive ion
Single proton – no eAttacks chemical bonds
Acids release H+
Bases
• NaOH  Na+
+
• Bases release OH
-
OH
-
• Strong acids and bases are highly
reactive – attack and break chemical
bonds – dangerous to living tissues
Neutralization Reaction
• Mixing an acid and a base OH- cancels
H+
• H+
+ OH-  H2O
Acids and Bases
• pH – a measure of the relative amounts of
hydronium (H3O or H+) and hydroxide
ions (OH )
• pH = power of hydrogen
• In water these ions form naturally
• Pure water contains equal numbers of H+
and OH- ions
• Neutral – OH = H+
pH Scale
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Ranges from 0 to 14
0 is very acidic – H+
7 is neutral OH = H+
14 is very basic (alkaline) OH
• A difference of 1 on
the pH scale is
actually a difference
of 10 times the
strength of acids or
bases
Acids
• Acid solution
– contains many more H+ ions
that OH ions
• Ex. HCl (hydrochloric acid) or H2SO4 (sulfuric
acid)
• Have a sour taste, produce a tingling or
burning sensation if they come in contact with
skin, highly corrosive when concentrated
• Ex. Citric acid – oranges, lemons and
grapefruits
Bases
• Base solution – a solution that contains
many more hydroxide ions (OH ) than
hydronium ions (H3O+)
• Ex. NaOH
• Alkaline refers to bases
• Have a bitter taste, feel slippery
Importance of pH
• certain pH’s are needed for different
reactions in the body
• Certain organisms need a certain pH to live
• Ex. Fish
Suspensions
• A mixture in which particles spread through
a liquid or gas but settle overtime
4-2 Chemical Compounds in
Living Things
• Elements
– 90 naturally occurring
– 11 common in organisms
– 20 trace
– 96.3% of the body – C, N, O, H
• In varying combinations the
elements C, H, N, O make up
practically all the chemical
compounds in living things
Inorganic Compounds
• No C
• Exception – CO2
• Ex. Water, minerals, salts
Organic Compounds
• Have C
• “organic chemistry”
• C makes about 2 million compounds
• Carbon is unique – remarkable ability to
form stable and strong covalent bonds
• Carbon can form 4 single covalent bonds
• Methane – CH4 – chemical formula
• Structural Formula
• Carbon can bond with O, N, P, S
• Carbon can form chains of C atoms – unlimited
length
• C atoms can bond either single, double or triple
• Carbon needs 4 bonds to be “happy”
Carbon Atoms Form
Covalent Bonds
Carbon Formations
• Chains
• Rings
• Mixes of single, double, triple bonds
Polymerization
• Taking smaller C compounds and joining
them to form larger compounds
Monomers
• Small compounds
• Ex. sugar
Polymers
• Many monomers joined together
Macromolecule
• A large polymer
• Macro = giant
• Polymerization allows us to join
monomers together to get complex
molecules
• Ex. Alphabet – 26 letters – many
combinations make many words
4.3 Compounds of Life
• 4 groups of organic compounds
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Carbohydrates – pasta, bread
Lipids – fats, oils, waxes
Proteins – meat
Nucleic acids – DNA and RNA
Carbohydrates
• Ex. Sugars and starches made of C, H, O
• O to H ratio 1:2 like water, C varies
• 1C:2H:1O
Monosaccharides
• Simplest carbohydrate
• One sugar
• Ex. Glucose – sugar – green plants make
Fructose – in fruits
Galactose – in milk
• All three – C6H12O6
• The 3 differ on how the atoms are
arranged
• Isomer - have the same number of atoms
but they are arranged differently
Importance of Sugars
• Contain a lot of energy
• Energy stored in the bonds
• Break bonds  release energy
Dehydration Synthesis
• Complex carbohydrates made by the
process of polymerization
• Chemical bonds linked
• Bond formed between OH-’s
• Dehydration synthesis – removes a water,
two monomers join
• Fig. 4-12
Dissacharide
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Made of 2 monomers
Ex. Sucrose – table sugar
Maltose – malt sugar
Lactose – milk sugar
Polysaccharides
• “many sugars”
• Forms that living things
use to store extra sugar
• Ex. Starch, Glycogen,
Cellulose
Starch
• How plants store extra sugar – potatoes
• 100’s of glucose molecules
Glycogen
• How animals store extra sugar – liver and
muscles
• 100’s and 1000’s of glucose molecules
• “animal starch”
Cellulose
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In plants
Support to plants
Strength and rigidity
Major component of wood
Hydrolysis
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Splits apart polysaccharides
Reverse of dehydration synthesis
Water breaks the bonds
Fig 4-14
Lipids
• Waxes – solid at RT
• Oils – liquid
• Fats – solid
Three Roles in Organisms
1. Store energy
2. Form biological membranes (cell
membranes)
3. Chemical messengers
• Lipids – fatty acids (3) + glycerol
• Fatty acid – long chain of C’s with a
carboxyl group (COOH)
• -OH = hydroxyl group
Glycerol
• Organic alcohol
Saturated and Unsaturated
Lipids
• Saturated – all C’s connected by single
bonds
• Unsatuarated – all C’s connected by
single and double bonds
• Polyunsaturated – many double bonds
• Fig – 4-18
• Lipids from saturated fatty acids 
saturated fats
• Found in meats and most dairy products
• Lipids from polyunsaturated fatty acids 
polyunsaturated fats
• Liquid at room temperature
• Cooking oils
• Unsaturated fats can reduce heart
disease
• Plants and animals use lipids to store
energy
• Produce more energy than carbs gram for
gram
Sterols and Phospholipids
• Sterol - ex. Cholesterol
• Important for building cells and
carrying messages
• Phospholipids – ½ dissolves in
water ½ doesn’t
• When mixed in water they form small
balloon like structures = liposomes
• Liposome – double layer – bilayer
• Form spontaneously
• Form cell membranes
Proteins
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Contain C, H, N, O
Polymers of amino acids (AA’s)
AA’s – amino group on one end – NH2
Carboxyl group on the other end - COOH
• NH2 and COOH can form covalent bonds
• AA’s can link together
• All AA’s have a similar chemical structure
and differ only in R group
• 20 AA’s
Peptides
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Peptide bond – covalent bond joins AA’s
H2O is lost when formed
Dehydration synthesis
Dipeptide – 2 AA’s
Tripeptide – 3 AA’s
Polypeptide – many AA’s - protein
Protein Structure
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One or more polypeptide chains
Roles:
1. Help to carry out chemical
reactions
2. Pump molecules in and out of cells
3. Help cells move
Enzymes are Proteins
• Chemical reaction makes life possible
• Speed up chemical reaction
Catalyst
• substance that speeds up the rate of a
chemical reaction
• Are not changed by the reaction
• Lower the start up energy
• Enzymes are catalysts – most are proteins
• Enzymes speed up a reaction by binding
to the reactants
• Substrate – reactants that are affected by an
enzyme
• Active site – place on an enzyme where the
substrate binds
• Enzymes are very specific.
Nucleic Acids
• C, O, H, N, P
• Polymers of individual monomers known
as nucleotides
• Nucleotide made of: phosphate group, 5
carbon sugar, nitrogenous base
• Two – DNA and RNA
• Store and transmit genetic information
The End