Biology 211
Anatomy & Physiology I
Dr. Thompson
Macromolecules of Importance
to Human Anatomy & Physiology
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:
Proteins
Carbohydrates
Lipids
Nucleic Acids
All of these macromolecules
are polymers which consist
of repeating smaller subunits
called monomers
Polymer:
Monomers
Protein
Carbohydrate
Lipid
Nucleic Acid
Amino acids
Monosaccharides
Fatty acids & Glycerol
Nucleotides
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: Fatty Acid
Example: Phospholipid
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
Amino acids
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 its
primary structure
Thus, the proteins
Glycine - Alanine - Glutamine - Alanine - Serine
and
Alanine - Alanine - Glycine - Serine - Glutamine
have different primary structures even though they
contain the same amino acids
(Scientists are lazy: Amino acids are
often shown as circles instead of
drawing out all the atoms)
The chain of amino acids in a protein will fold into
specific patterns, called its secondary structure
Different parts of each chain fold in different ways;
Thus, they have different secondary structures
This folded protein folds even further to form its
tertiary structure
Since proteins with different primary structures will
fold into different secondary structures, they will also
fold into different tertiary structures
These folded proteins may group together, providing the
protein with its quaternary structure.
Obviously, proteins with different primary structures
will have different secondary structures
and thus different tertiary structures
which will group into different quaternary structures
Hemoglobin
Immunoglobulin (antibody)
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
Monosaccharides
Lipid
Fatty acids & Glycerol
Nucleic Acid
Nucleotides
Different monosaccharides have different structures,
but all share the same basic formula: Cn H2n On
Most common monosaccharides:
Also found:
C6 H12 O6
C3 H6 O3
C4 H8 O4
C5 H10 O5
2 monosaccharides = disaccharide
2 monosaccharides = disaccharide
3 monosaccharides = trisaccharide
Many monosaccharides = polysaccharide
(too many to count)
Fuzzy terminology: Monosaccharides
= sugars
Disaccharides
Sometimes: All monosaccharides
disaccharides
polysaccharides
called "sugars"
Sometimes: All monosaccharides
disaccharides
polysaccharides
called "carbohydrates"
Two Important Functions of Carbohydrates:
1) Storage of fuel for energy:
Amylose (starch) in plants; Glycogen in animals
Human cells can digest starch but not synthesize it.
They can both synthesize & digest glycogen
Two Important Functions of Carbohydrates:
Digestion of starch or glycogen in
the digestive system produces Glucose
(Scientists are lazy: Glucose & other
monosaccharides are often shown as
hexagons instead of drawing out all
the atoms)
which is further broken down within
cells to release lots of energy.
Waste products: Carbon dioxide
Water
Two Important Functions of Carbohydrates:
(1. Storage of fuel for energy)
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)
We will discuss the use of carbohydrates for producing
energy and for use as structural molecules a various
times throughout this course and BIOL 212
Polymer:
Monomers:
Protein
Amino acids
Carbohydrate
Monosaccharides
Lipid
Fatty acids & Glycerol
Nucleic Acid
Nucleotides
Lipids: Molecules which are hydrophobic and do not mix
with water
Two major types: Fats (& Oils)
Steroids
Fats & Oils:
Monomer (basic repeating units) are fatty acids bound
to a 3-carbon molecule called glycerol
If it’s solid at room temperature it’s a fat
If it’s liquid at room temperature it’s an oil
Fatty acids
Glycerol
(Scientists are lazy: Fatty acids are often shown as wavy lines
instead of drawing out all the atoms)
Fatty acids are long carbon chains (up to 20 or more
carbons) with a carboxyl group at one end.
If they have no double
Bonds between carbons,
they are called
saturated fatty acids
If they have one or more
double bonds between
carbons, they are called
unsaturated fatty acids
Glycerol is a 3-carbon molecule to which fatty acids
bond by dehydration synthesis
Most common:
Diglycerides
(2 fatty acids
bound to
glycerol)
Triglycerides
(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 from
triglycerides and diglycerides and and broken down to
release energy
(we’ll discuss the details in BIOL 212)
Related to triglycerides are phospholipids, in which one
fatty acid is replaced by a phosphate-containing group.
Phospholipids are major components of cellular membranes
because the phosphate-containing group is highly
hydrophilic while the fatty acids are highly hydrophobic
(Scientists are lazy:
Instead of drawing out all
the atoms, phospholipids
are often shown as a
circle for the phosphate
group with wavy lines for
the two fatty acids)
Phospholipids are also the surfactant molecules which allow
the small air sacs (alveoli) of the lungs to stay open
Fats and oils are one type of “lipid”
Another type of lipid: Steroids
Do not contain glycerol or fatty acids
Hormones from adrenal gland
testes
ovaries
Cholesterol
Vitamin D
Bile Salts (help absorb fat)
(other places)
Polymer:
Monomers:
Protein
Amino acids
Carbohydrate
Monosaccharides
Lipid
Fatty acids & Glycerol
Nucleic Acid
Nucleotides
Each nucleotide has three parts:
Ribonucleic acid
(single chain)
Deoxyribonucleic acid
(double chain)
There are five different base
groups in nucleic acids
Both DNA & RNA
Adenine
DNA
Cytosine Guanine
RNA
Thymine
Uracil