Biology 211
Anatomy & Physiology I
Macromolecules
Many molecules in the human body are very large,
consisting of hundreds or even thousands of atoms.
These are called macromolecules.
Four types of macromolecules are particularly
important in the human body:
P
C
L
N
All of these macromolecules are polymers which
consist of repeating smaller subunits called monomers
Polymer:
Protein
Carbohydrate
Lipid
Nucleic Acid
Monomers
All of these monomers and polymers consist of chains or
rings of covalently bonded carbon atoms, with other
atoms (primarily hydrogen, oxygen, nitrogen, and
phosphorus) attached.
Therefore, these are defined as organic molecules.
Example: Phospholipid
Example: Fatty Acid
Rather than draw out these large organic molecules, we
typically use a set of shorthand figures for them
Amino acids are usually
shown as circles
Monsaccharides are
usually shown as
polygons showing the
number of carbons
Fatty acids are usually
shown as wavy lines
Nucleotides are usually
shown with three parts
Polymer:
Monomers:
Protein
Carbohydrate
Monosaccharides
Lipid
Fatty acids & Glycerol
Nucleic Acid
Nucleotides
Proteins form parts of cell membranes
enzymes
antibodies
some hormones
molecules which produce movement in
muscle
fibers in the extracellular matrix
... many other molecules
Some proteins exist alone, but many are combined
with carbohydrates to form glycoproteins
Proteins are composed of unbranching chains of amino acids
arranged in different sequences. There are 21-22 different
amino acids, all of which have the same basic structure:
Where "R" is different for
each amino acid
Amino
Group
Carboxyl
Group
The sequence of amino acids in a protein is called
Thus, the proteins
Glycine - Alanine - Glutamine - Alanine - Serine
and
Alanine - Alanine - Glycine - Serine - Glutamine
have different
structures even though they
contain the same amino acids
The chain of amino acids in a protein will fold into
specific patterns, called
Different parts of each chain fold in different ways;
Thus, they have different
structures
This folded protein folds even further to form
Since proteins with different primary structures will
fold into different secondary structures, they will also
fold into different
structures
These folded proteins may group together, providing the
protein with
Obviously, proteins with different primary structures
will have different secondary structures
and thus different tertiary structures
which will group into different quaternary structures
The specific function of any protein depends on its
three-dimensional shape (secondary, tertiary, and
quaternary structures)
If the shape of the protein is changed, it will no longer
function as it should.
This is called denaturing the protein
Polymer:
Monomers:
Protein
Amino acids
Carbohydrate
Lipid
Fatty acids & Glycerol
Nucleic Acid
Nucleotides
Different monosaccharides have different structures,
but all share the same basic formula:
Most common monosaccharides:
C6 H12 O6
Also found:
C3 H6 O3
C4 H8 O4
C5 H10 O5
2 monosaccharides =
2 monosaccharides =
3 monosaccharides =
Many monosaccharides =
Fuzzy terminology: Monosaccharides
= sugars
Disaccharides
Sometimes: All monosaccharides
disaccharides
polysaccharides
called "sugars"
Sometimes: All monosaccharides
disaccharides
polysaccharides
called "carbohydrates"
Functions of carbohydrates:
1) Storage of fuel for energy
Amylose (starch) in plants
Glycogen in animals
Human cells can digest amylose but not synthesize it.
They can both synthesize & digest glycogen
Functions of carbohydrates:
2) Structural carbohydrates
Cell walls in plants / bacteria = cellulose & others
Exoskeletons of invertebrates = chiton
Many in extracellular matrix of all tissues
Receptors on cell surfaces
(usually bound to proteins or lipids)
Polymer:
Monomers:
Protein
Amino acids
Carbohydrate
Monosaccharides
Lipid
Nucleic Acid
Nucleotides
Lipids: Molecules which are hydrophobic and do not mix
with water
Two major types:
Fats & Oils:
Monomer (basic repeating units) are
to a 3-carbon molecule called
bound
Fatty acids are long carbon chains (up to 20 or more)
with a carboxyl group at one end.
If they have no double bonds between carbons, they are
called
fatty acids
If they have one or more double bonds between
carbons, they are called
fatty acids
Glycerol is a 3-carbon molecule:
to which fatty acids bond by
dehydration synthesis
Most common:
(2 fatty acids
bound to
glycerol)
(3 fatty acids
bound to
glycerol)
Diglycerides and triglycerides are energy-storage molecules.
They can be found in most type of cells, but are primarily
found in adipocytes, in which they form large fat droplets in
the center.
When needed for energy, fatty acids can be released and
broken down to release energy to form ATP
Related to triglycerides are the
, in which
one fatty acid is replaced by a phosphate-containing group.
Phospholipids are the major component of all cellular
membranes
Phospholipids are also the surfactant molecules which allow
the small air sacs (alveoli) of the lungs to stay open
Other type of lipid: Steroids
Do not contain glycerol or fatty acids
Basic unit
= sterol
Cholesterol
Other steroids include Vitamin D
Bile Salts (help absorb fat)
Hormones from adrenal gland
testes
ovaries
Polymer:
Monomers:
Protein
Amino acids
Carbohydrate
Monosaccharides
Lipid
Fatty acids & Glycerol
Nucleic Acid
Each nucleotide has three parts:
Rribonucleic acid
(single chain)
Deoxyribonucleic acid
(double chain)
There are five different base
groups in nucleic acids
Both DNA & RNA
A
DNA
C
G
RNA
T
U