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Biology 12
Molecules of Life – organic biochemistry
 To be considered organic, molecules must
contain
Carbon and Hydrogen atoms.
Practice; organic or not?
Yes
 CH4
No
 H2O
No
 CO3
 C6H12O6 Yes
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Molecules of life
•Dalton’s theory of the Atom states that all matter is
made of atoms. Hence, all organic life is made of atoms.
•The atoms that are most important to life are;
¤Carbon (C)
¤Chlorine (Cl)
¤Oxygen (O)
¤Phosphorous (P)
¤Hydrogen (H)
¤Potassium (K)
¤Nitrogen (N)
*There are many others need for life but
these are the major ones.
¤Sodium (Na)
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Carbon
 Carbon’s ability to form up to 4 covalent
bonds with other atoms allows for the
creation of a variety of geometric
structures.
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Isomers
 Molecules with the same chemical formula
but with a different arrangement of atoms.
 Isomers possess different shapes and
different physical and chemical properties.
 There are 2 types of isomers:
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1. Structural isomers
 Their atoms are linked together differently.
Example: Glucose and Fructose (Formula for
both is C6H12O6)
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2. Sterioisomers
 the bond structure is the same, but the
geometrical positioning of atoms and
functional groups in space differs. For
example glucose and galactose.
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Functional groups
 These groups are hydrophilic and typically
polar with the exception of the phosphate
group and therefore increase the solubility
of the organic molecule to which they are
attached. Ex: the hydroxyl (-OH) in ethanol
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Macromolecules
 Small molecules can join together to form
larger structures called macromolecules.
 They are formed of long chains called
polymers
 The molecular sub-units of a polymer chain
are called monomers
 Ex: carbohydrates, proteins, lipids and
nucleic acids
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Molecules of Life
 Two major reactions will build them up
(anabolism) or degrade them (catabolism)
•Condensation and Hydrolysis are used to break
down and form and other molecules of life.
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1. Condensation
• When two monosaccharides combine to form a
disaccharide one loses 1H and the other loses
1H and 1O.
• The 2H and 1O join to form 1 water molecule.
• This release of H2O is called condensation.
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Molecules of Life
A. Condensation Reaction create the
polymer chains.
Water
moleule
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Molecules of Life
B. Hydrolysis: the breaking down of molecules by adding
water
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Molecules of Life
Divided into 4 categories.
The four major molecules necessary for life
are lipids, carbohydrates, proteins and
nucleic acids.
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Carbohydrates
glucose
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Molecules of Life
Carbohydrates:
•composed of C,H, and O. (ratio of 2H to 1O)
•Primary source of molecular energy.
•Produced by plants in the form of simple sugars (glucose,
fructose, galactose) and polysaccharides (starch, cellulose).
•Simple sugars (ie. Glucose monomer) C6H12O6 are called
monosaccharides
•Two glucose molecules form a disaccharide.
•More than two sugar molecules joined make a
polysaccharide.
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Lipids
triglyceride
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Molecules of Life
LIPIDS:
•composed of C,H,and O (ie. C57H110O6)
•they are used in storing excess energy long term,
and building of the cellular membrane. They help
in the transmission of messages in the body as
well.
•Produced by both plants and animals as fats, oils, waxes
and steroids.
•Composed of fatty acid subunits attached to a glycerol
(triglyceride) or other organic compound
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Amino acid
Proteins
R group
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Molecules of Life
Proteins:
•composed of C, H, O and N (nitrogen is a necessary element for forming amino acids,
the building blocks of proteins)
•a single protein may be formed from 100’s of amino acid monomers
•two amino acids make a dipeptide
•more make up a polypeptide
•Enzymes and hormones are examples of polypeptides. Enzymes
are catalysts for chemical reactions.
•The type of polypeptide formed depends on the number and sequence of
the amino acids that make it.
(there are 20 different amino acid groups).
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Nucleic Acids
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Molecules of Life
Nucleic Acids: composed of subunits called
nucleotides.
DNA (deoxyribonucleic acid)
RNA (ribonucleic acid)
These acids form the code that controls an organisms
basic behavior and appearance.
ATP is a nucleotide used to drive virtually all the
energy in a cell.
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