Macromolecules
Introduction:
 All
compounds can be classified in 2
broad categories:
1.
2.
Organic compounds- Contain carbon
and hydrogen atoms
Inorganic compounds- Can have one or
the other, but do not contain both carbon
and hydrogen atoms
A. Most of your body’s molecules
are organic compounds.
a.
Macromolecules are built from small organic
compounds the same way a railroad train is built,
by linking a lot of smaller units together into long
chains.
i.
ii.
iii.
Large carbon compounds are built up from smaller
simpler molecules called monomers (mono = one )
Monomers can bind to one another to form complex
molecules known as polymers (poly = many)
A polymer consists of repeated, linked units, which can
also bind forming large polymers called Macromolecules.
(macro = large)
Monomers link to form polymers through a
chemical reaction called condensation
reaction or dehydration synthesis. During
the formation of polymers, Water (H2O), is
released or is the by-product of the
reaction.
c. The breakdown of some complex
molecules, such as polymers, occurs
through a process known as hydrolysis.
i.
Hydrolysis is the reverse of a
condensation reaction. The addition of
water, to some polymers can break the
bonds that hold them together.
b.
There are four main types of macromolecules
found in living organisms:
1.
Carbohydrates
2.
Lipids
3.
Proteins
4.
Nucleic Acids
I. Carbohydrates
Composed of carbon, hydrogen, and oxygen
atoms in the proportion of 1 : 2 : 1
i.
General formula: (CH2O)n where n is the
number of carbon atoms.
1.
a.
ii.
Example: The sugar glucose is a small carbohydrate;
its n equals 6. Therefore its chemical formula is
C6H12O6.
The building blocks (or monomers) of
carbohydrates are monosaccharides.
Monosaccharides are simple sugars (saccharide =
sugar). Examples:
iii.
Glucose: commonly found in blood of animals
Galactose: a simple sugar found in milk
Fructose: commonly found in fruit
1.
2.
3.
a.
Glucose and Fructose both have the formula C6H12O6,
Sometimes compounds may have the same formula,
however they have different structures/ arrangements.
In such cases, those compounds are called isomers.
Disaccharides contain 2 monosaccharides joined
by dehydration synthesis. Examples:
iv.
1.
2.
Lactose: commonly found in milk, made up of
Galactose + Glucose
Sucrose: “table sugar”, transported in plants, made up
of Fructose + Glucose
Polysaccharides are carbohydrates formed
from linking individual sugars into long chains.
Examples:
v.
1.
2.
3.
Starch: a common storage form of glucose in
plants (breads, pasta, potatoes)
Cellulose: a polysaccharide contained in the
cell walls of plants; gives strength and rigidity to
plant cells.
Glycogen: a common storage form of glucose
in animals (stored in the muscles and liver to be
used as quick energy)
II. Lipids (include fats, oils, waxes, etc.)
i.
ii.
Class of macromolecules that do not dissolve in
water
Lipids usually serve one of three functions:
1.
2.
3.
iii.
iv.
Energy storage
structural support in cell membranes (phospholipids)
serve as reactants (starting materials) for metabolic
reactions
Fatty acids are the building blocks (or
monomers) that make up most lipids.
A common lipid that contains fatty acids is a
triglyceride. Triglycerides (referred to as neutral
fats) are glycerol linked to three fatty acids (in
the shape of an “E”) by condensation reaction.
III. Proteins
Proteins are organic compounds composed
mainly of carbon, hydrogen, and nitrogen
atoms.
Proteins are the construction materials for body
parts such as hair, skin, nails, and blood.
Amino acids are the building blocks (or
monomers) that make up most proteins
i.
ii.
iii.
1.
iv.
There are 20 different kinds of amino acids that
humans use.
One important group of proteins - enzymes help control chemical reactions by acting
as catalysts. Catalysts speed up reactions by
lowering activation energy.
IV. Nucleic Acids
Nucleic Acids are complex organic molecules
that store genetic information in the cell.
Nucleotides are the building blocks (or
monomers) that make up most nucleic acids.
i.
ii.
Nucleotides consist of a sugar (pentose) + base
(nitrogenous) + phosphate.
i.
Example- DNA nucleotide:
Main types of nucleic acids
iii.
DNA = Deoxyribonucleic acid
1.
a.
Is the genetic information inside the nucleus of cells
RNA = Ribonucleic acid
2.
a.
Instructions which code for protein synthesis
Review Questions
sucrose
glucose starch
C6H12O6
cellulose
glycoge
n
C12H24O1
2
Monosaccharides
Polysaccharides
glucose
starch
C6H12O6
cellulose
fructose
glycogen
Disaccharides
sucrose
C12H24O12
fructose
Description
Commonly called fats and oils
Lipids Nucleic
Acids
Proteins Carbs
X
Contain carbon, hydrogen, and
nitrogen
X
Contain peptide bonds
X
DNA and RNA are examples
X
Follow the general formula (CH2O)n
X
Form skin, blood, hair, muscles
X
Lactose and cellulose are examples
X
Made up of amino acids
X
Made up of nucleotides
X
Most consist of 3 fatty acids bonded
to a glycerol
X
Used for long-term energy storage
X