Organic Molecules
Molecules
that contain carbon and hydrogen
4 major classes: carbohydrates, lipids,
proteins and nucleic acids
Inorganic versus Organic Molecules
Inorganic
organic

Usually contain +,- ions
always contain carbon and
hydrogen

Usually ionic bonding
always covalent bonding

Always contain a small # of atoms
Often quite large, many atoms

Often associated with nonliving
matter
usually associated with living
organisms
Carbon atom

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

Needs 4 electrons to complete its outer shell
Can share with as many as four other
elements
Often shares electrons with another carbon
atom
Hydrocarbons – carbon atoms bonded
exclusively with hydrogen atoms
Functional Groups

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

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Specific combination of bonded atoms that always
reacts in the same way
Connected to the carbon backbone of the organic
molecule
Figure 3.2
Hydrophobic – not soluble in water
Hydrophilic – soluble in water
Determines the polarity of an organic molecule and
the types of reactions that will occur
isomers


Organic molecules that have identical
molecular formulas but a different
arrangement of atoms.
Ex. Glyceraldehyde and dihydroxyacetone


C3H6O3
Glucose, fructose, galactose
Macromolecules

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Polymers – largest macromolecules, made
up of monomers
Monomers – linked together, make up
polymers
Amino acids = proteins
Nucleotides = nucleic acids
Sugars = carbohydrates
Fats = glycerol and fatty acids (not a
polymer)
Synthesis and degradation of polymers

Dehydration reaction – the equivalent of a water
molecule (-OH hydroxyl group) and (-H hydrogen
atom) is removed as the reaction occurs to
synthesize a macromolecule.

Hydrolysis reaction – used to degrade a
macromolecule, -OH group from water attaches to
one subunit and an –H from water attaches to the
other subunit. Water is used to break the bond
holding the subunits together.
Carbohydrates

Energy source and structural component
1:2:1 ratio of carbon to hydrogen to oxygen

Monosaccharides – single sugar


Glucose, 6 carbon sugar


Major source of cellular fuel
Ribose, deoxyribose, 5 carbon sugars, DNA, RNA
Disaccharides

2 monosaccharides




Dehydration reaction
Glucose + glucose = maltose
Glucose + fructose = sucrose (table sugar)
Glucose + galactose = lactose (milk sugar)
Polysaccharides
Short term energy storage

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

Much larger than sugars
Helical in shape
Not as soluble in water
Cannot easily pass through the cell
membrane
Plants


Store glucose as starch
Animals

Store glucose as glycogen in the liver
Polysaccharides: structural molecules

Plants

Cellulose


Animals and fungus


Most abundant organic molecule on earth!
Chitin
Bacteria

peptidoglycan
Lipids – long term energy storage



Insoluble in water
Used for insulation and long term energy
Includes fats, oils, phospholipids, steroids
and waxes
Triglycerides: fats and oils

Glycerol – contains 3 –OH groups, polar



3 fatty acids (hence triglyceride)
Fatty acids prevent fats and oils from mixing with
water
Fatty Acids

Saturated – no double bonds between carbons


Solid at room temp, animal origin
Unsaturated – double bonds, liquid at room temp,
usually of plant origin
Phospholipids, steroids, waxes

phospholipids



Glycerol and phosphate group = polar head
2 fatty acid chains = nonpolar tails
Steroids

Skeletons of four fused carbon rings (different lipid
structure)
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Cholesterol – animal plasma membrane
Estrogen, progesterone, testosterone
Waxes


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Long chain of fatty acid and alcohol
Hydrophobic, waterproof
Skin and fur maintenance, repels insects, protection
Proteins

Functions

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Support – keratin, collagen
Enzymes – speed chemical rxns
Transport – channel and carrier, hemoglobin
Defense - antibodies
Hormones – insulin, growth
Motion – actin and myosin
Proteins

Amino acids  dehydration reaction 
protein



Bonded by covalent bond called peptide bond
Peptide – 2 or more amino acids bonded
Polypeptide – chain of many amino acids
Protein shape determines its function

Primary – polypeptide

Secondary – polypeptide coils or folds,
hydrogen bonds



Alpha - helix
Beta – pleated sheet
Fibrous proteins and keratin
Protein shapes

Tertiary – globular, three dimensional
 Various bonding results in rounded shape
 Enzymes, can be denatured by temp, pH

Quaternary – consist of
more than one polypeptide
Ex. Hemoglobin
Diseases can be caused because
proteins do not fold the right way
Ex. Prions, mad cow disease

Nucleic Acids: DNA, RNA, ATP


Nucleotides: nitrogen base, phosphate, 5 carbon
sugar
DNA




Double stranded
Deoxyribose
A,T,C,G
RNA



Single stranded
Ribose sugar
A,U, C, G
Adenosine Triphosphate - ATP


High energy molecule
Composed of adenine and ribose


3 phosphate groups attached to ribose
Phosphate bond is hydrolyzed to ADP + P,
releasing energy