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MACROMOLECULES
Carbohydrates - Lipids
Proteins - Nucleic Acids
1. Most Macromolecules are
Polymers
• From the greek polys for “many” and meris for
“part”
• A long molecule consisting of many similar
building blocks
• Building blocks are linked by covalent
bonds
• Macromolecule polymers include proteins,
carbohydrates and nucleic acids
• Repeating units that serve as building
blocks are called “monomers”
• Monomers are
connected by a
reaction in which two
molecules are
covalently bonded to
each other through a
loss of a water
molecule
• This is called a
dehydration reaction
• Polymers are disassembled into monomers
by hydrolysis
• Hydrolysis is a process where bonds
between monomers are broken by a water
molecule
2. Carbohydrates
• Include both sugars and their
polymers
• Serve as fuel and carbon sources
Monosaccharides
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Single sugar monomers
Known as simple sugars
Chemical formulas are multiple of CH2O
Classified based on number of carbons and
arrangement of atoms
• Sweet tasting, colorless, crystalline
Glucose – C6H12O6
Disaccharides
• Consists of two
monosaccharides
linked by a
covalent bond
formed by a
dehydration
reaction (water
molecule is
produced)
• Maltose is a disaccharide formed by
linking two monosaccharides of glucose
• Also known as malt sugar
• Used as an ingredient in brewing beer
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Sucrose is the most common disaccharide
Known as table sugar
Its two monomers are glucose and fructose
Plants carbohydrates from leaves to roots in
the form of sucrose
• Lactose is a disaccharide present in
milk
• Consists of glucose and galactose
monomers
Polysaccharides
• Polymers with a few hundred to a few
thousand monomers
• Some serve as storage molecules
• Some serve as building materials for
structures that protect the cell
Storage Polysaccharides
• Starch is a storage polysaccharide in
plants
• This stored starch represents stored
energy
• To use this energy plants break the bonds
between monomers by hydrolysis
• Humans can also use hydrolysis to get
energy from plant starch
• Wheat, corn and rice are sources of plant
starch in the human diet
• Glycogen is a storage polysaccharide in
animals
• Humans and other vertebrates store
glycogen mainly in liver and muscle
cells
• In humans the glycogen storage is depleted
in about one day unless replenished with
food
Structural Polysaccahrides
• Organisms build strong materials from
structural polysaccharides
• Cellulose is a major component of the
tough cell walls that enclose plant cells
• Grouped cellulose molecules are called
microfibrils
• Microfibrils are strong cables that are the
building materials for plants
• Wood that we use for lumber is rich in
cellulose
• Humans cannot digest cellulose, but it is an
important part of a healthy diet
• Cellulose, or fiber, abrades the wall of the
digestive tract, encouraging mucus
secretion
• This aids in the smooth passage of food
through the tract
• Chitin is another
structural
polysaccharide
• It is used by
arthropods
(insects, spiders,
crustaceans) to
build their
exoskeletons
3. Lipids
• Lipids are macromolecules that do not
include polymers
• Compounds called lipids are grouped
together because of their hydrophobic
behavior
• They consist mostly of hydrocarbons
• Lipids include
fats,
phospholipids and
steroids
• Other families of
lipids include
waxes and certain
pigments
butter
Skateboard wax
• The base unit for all lipids is a fatty acid
Hydrocarbon tail
Carboxyl head
Fats
3
Fatty
Acids
• A fat is constructed from two types of
smaller molecules; glycerol and fatty
acids
1
glycerol
• Fatty acids vary in length and in the
number and location of double bonds
• The term saturated and unsaturated fats
are commonly used in nutrition
Lard – a
saturated fat
• Fats separate from water because the
water molecules hydrogen bond with
each other and exclude the fats.
Saturated Fatty Acid
• Also known as saturated fat
• Contains no double bonds between
carbons in hydrocarbon tail
• This means as many hydrogen atoms
as possible are bonded to the carbon
skeleton
• Most animal fats
are saturated
• Solid at room
temperature
• Examples are
butter and lard
Unsaturated Fatty Acid
• Also known as unsaturated fat
• Contains one or more double bonds due to the
removal of a hydrogen atom
• A kink in the shape will occur wherever a
double bond occurs
• Fats of plants and fishes
are generally
unsaturated
• Referred to as oils,
liquid at room
temperature
• Examples are corn oil
and cod liver oil
Phospholipids
• Similar to fats but have
only two fatty acids
instead of three
• Also contain a
phosphate group with
the glycerol head which
has an affinity for water
• Hydrocarbon tails are
excluded from water
• When added to water,
phospholipids self
assemble into groupings
that shield the tails from
water
• At the surface of a cell
phospholipids are
arranged into a bilayer
(double layer)
• This forms a boundary
between the cell and its
external environment
Steroids
• Consist of a carbon skeleton with four fused
rings
• Cholesterol is a steroid that is a component of
animal cell membranes
• Many hormones, including sex hormones, are
steroids
4. Proteins
• Humans have tens of thousands of
proteins
• Each protein has a specific structure
and function
• They are the most structurally
sophisticated molecules known
• Amino acids are the sub unit of proteins
• All proteins are polymers constructed
from the same set of 20 amino acids
• Polymers of amino acids are called
polypeptides
Four levels of protein structure
• Primary structure - the unique sequence
of amino acids
• Secondary structure - the sequence of
amino acids in a polypeptide is coiled or
bent
• Tertiary structure folding and bonding
between side
chains of amino
acids
• Quaternary
structure - two or
more poly peptide
chains are joined
together
• Collagen is a
fibrous protein
• This super-coiled
protein has great
strength and is
found in tendons
and ligaments
• Hemoglobin is a protein in blood that
has a quaternary structure and is known
as a globular protein
• If ph, salt concentration or temperature
of a proteins environment change, the
protein may unravel
• This is called denaturation
• A denatured protein can no longer
perform its function
5. Nucleic Acids
• Nucleic acids are polymers of monomers
called nucleotides
• There are two types of Nucleic Acids
– Deoxyribonucleic acid (DNA)
– Ribonucleic acid (RNA)
DNA
• Nucleic acids forms genes which enable
living organism to reproduce from one
generation to the next
• Nucelotides are composed of three
parts
–A nitrogen base
–A pentose (5 carbon sugar)
–A phosphate group (PO4)
• Nucleotides form nucleic acids which come
together to form genes
• Genes determine the structure and shape of
proteins
• Genes (DNA) and their products (proteins)
document the heredity background of an
organism
The End
finally