THE CHEMISTRY OF ORGANIC MOLECULES
I. MACROMOLECULES-large molecules that are composed of smaller molecules and atoms
that are bonded together. These are among the largest of all chemical molecules.
A. Polymers-the largest of the macromolecules. These are composed of numerous, small
identical subunits known as Monomers. There are 4 major polymers that are important for
living organisms. These polymers are; carbohydrates, lipids, proteins and nucleic acids.
B. Polymers are referred to as being organic compounds. Organic compounds are compounds
that contain the elements carbon and hydrogen.
1. Chemical Properties of Carbon
a. Carbon has 6 electrons. What is the structure of a carbon atom?
b. Carbon can form 4 single covalent bonds with other atoms. It also has the
ability to form double bonds with some atoms. Overall, the 4 bonds that
carbon forms with other atoms makes the carbon stable. This stability is what
makes carbon an important component of macromolecules.
C. Functional Groups-groups of covalently bonded atoms that have definite chemical properties.
1. These always react in the same way, regardless of what molecule they are a part of.
2. Some polymers have several functional groups.
3. The exact arrangement of a functional group in a molecule greatly influences and
determines the chemical properties of the particular molecule.
4. Important Functional Groups:
a. Hydroxyl
b. Carbonyl
c. Carboxyl
d. Amino
e. Sulfhydryl
f. Phosphate
II. Types of Reactions associated with Polymers:
A. Dehydration (Condensation) Reactions-reactions in which monomers bond together to
produce polymers.
1. Water is lost from the monomers in these reactions.
B. Hydrolysis Reactions-reactions in which polymers are broken down into monomers.
1. These reactions require an input of water to occur.
III. 4 MAJOR POLYMERS IN LIVING ORGANISMS
A. Carbohydrates
B. Lipids
C. Proteins
D. Nucleic Acids
IV. CARBOHYDRATES-includes sugars and related compounds.
A. Carbohydrates are composed of three major elements:
B. Carbohydrates tend to be very strong compounds due to the presence of carbon-hydrogen
covalent bonds.
C. Carbohydrates serve as a major source of energy for living cells. Some carbohydrates also
serve as structural compounds in living cells.
D. 3 Classes of Carbohydrates
1. Monosaccharides-simple sugars
a. These serve as monomers for many of the larger carbohydrates.
b. Structurally, these serve as rings or chains.
c. Types of Monosaccharides
1. Glucose-C6H12O6
a. Serves as a major energy source for living cells.
2. Fructose
a. Isomers-compounds with the same atoms and the same
number of atoms but, that have different structures. Glucose
and fructose are isomers of each other.
2. Dissacharides-sugars that are composed of 2 monosaccharides that are covalently
bonded together. These are formed by dehydration reactions.
a. Types of Disaccharides
1. Sucrose
2. Lactose
3. Maltose
3. Polysaccharides-sugars that are composed of more than 2 monosaccharides that are
covalently bonded together. These are often very large molecules.
a. What types of reactions are these formed by?
b. Types of Polysaccharides
1. Starch-a stored form of glucose in plant cells. Plants can use starch for
energy under times of need or stress. Amylose is a common starch.
2. Cellulose-makes up the cell wall of plant cells. This is a thick,
protective polysaccharide. Many animals do not contain the needed
enzymes to break this compound down. Deer, cows and a few other
animals have special bacteria in their stomachs that help digest and
breakdown cellulose.
3. Glycogen-the storage form of glucose in animal cells. Many animals
can convert glycogen into glucose under times of need or stress. This
glucose can then be used as an energy source. Glycogen is stored in
the liver and in some muscle fibers.
4. Chitin-a structural polysaccharide found in fungi and insects. This is
also a thick, protective compound.
V. LIPIDS-includes fats, oils and waxes.
A. All lipids are insoluble in water.
1. What does this mean?
B. Functions of Lipids in Living Organisms:
C. Structure of a Typical Lipid
1. Lipids are composed of 2 major components:
a. Glycerol-a 3 carbon alcohol.
1) Hydroxyl groups bond to each of the carbon atoms in glycerol.
2) Glycerol serves as the major backbone unit for most lipids.
b. Fatty Acids
1) Three fatty acid molecules attach to glycerol to form a lipid. Each
fatty acid replaces the hydrogen atom on the hydroxyl groups of the
glycerol molecule. Due to this, there is one fatty acid bonded to each
carbon atom of the glycerol molecule.
a) Due to this arrangement, lipids are often referred to as
triglycerides.
2) Saturated fats-occur when the fatty acid groups contain single covalent
bonds between their carbon atoms. There are no carbon to carbon
double bonds in these.
a) In other words, the carbon atoms are saturated with as many
hydrogen atoms as possible.
b) These are known as animal fats are solids at room temperature.
c) Are these bad for us?
3) Unsaturated fats-occur when fatty acids contain double bonds between
their carbon atoms. These are often referred to as vegetable oils.
a) Polyunsaturated fatsb) These types of fats are liquids at room temperature.
D. Types of Lipids
1. Phospholipids-contain only 2 fatty acid tails. These are found in cell membranes. They
have hydrophilic heads and hydrophobic tails.
2. Waxes-serve as protective coverings over surfaces.
3. Hormones-chemicals that regulate the growth and functioning of living organisms.
4. Steroids-there are several different types of steroids:
a. Cholesterol-common steroid.
1) Humans do need a small amount of cholesterol for:
a) The formation of Vitamin D
b) The production of estrogen and testosterone
2) Cholesterol is carried through the human body by 2 proteins that are
found in the human bloodstream:
a) Low-density Lipoprotein (LDL)-this protein is responsible for
delivering cholesterol to body cells and tissues where it is
needed. This is often referred to as the “bad cholesterol.”
b) High Density Lipoprotein (HDL)-this protein removes
cholesterol from cells and tissues and transports it to the liver
where it is secreted into bile. This is usually known as “good
cholesterol.”
1) Bile-compound that is secreted by the liver that aids in
digestion. Bile is also a waste product that is excreted
from the body. It contains fatty wastes and it is excreted
via feces.
3) Cholesterol in the human diet comes only from animal products.
4) Normal Cholesterol Readings in young individuals should be around
180mg/dl. This rises to 230-250 mg/dl as humans age.
5) An important issue relating to cholesterol is the LDL/HDL Ratio.
a) A high HDL values ensures that cholesterol is removed from
body tissues in an adequate fashion.
b) A low HDL values indicates that cholesterol removal is not
occurring as it should.
c) If cholesterol is not removed from the body, it can form
plaques or deposits in the arteries of the body. This is a major
cause of heart disease and heart attack.
6) How can an individual increase their HDL levels?
b. Anabolic Steroids
1) These steroids are thought to increase muscle mass.
2) Side Effects of Steroid Use Include:
c. Not all steroids are bad. Some are used to treat allergies and other human
illnesses. These steroids do not cause the side-effects mentioned above.
VI. PROTEINS
A. Functions of Proteins in Living Organisms
1. Make up cell membranes
2. Make up enzymes-
3. In collagen-protein that provides strength and support to structures in the body.
4. In keratin-a thick, protective protein.
5. Transport-some protein carry various materials through the body. An example would
be hemoglobin.
6. Defense-proteins are in antibodies.
7. Proteins make up the contractile portion of human muscle. The major contractile
proteins are actin and myosin.
B. Proteins are found in and are essential for both plants and animals.
C. Protein Structure
1. Proteins are composed of many amino acids that are bonded together.
2. Peptide Bonds-
3. Chains of bonded amino acids are often referred to as polypeptides.
4. What attaches amino acids together?
5. Amino Acids-there are 20 naturally occurring amino acids. They can bond in a variety
of sequences to produce proteins.
a. General Structure of an Amino Acid:
b. Some common amino acids include: phenylalanine, tryptophan, asparagine
6. Proteins can occur as simple chains or they can exhibit complex structures.
7. Denaturation-
a. What can cause denaturation to occur?
VII. NUCLEIC ACIDS
A. These are composed of nucleotides that are covalently bonded together. What forms these
bonds?
B. Individual Nucleotides Contain:
1. A 5 Carbon Sugar
2. A Phosphate group
3. A Nitrogen-containing base
C. Types of Nucleic Acids:
1. Deoxyribonucleic Acid (DNA)-
2. Ribonucleic Acid (RNA)-
3. Adenosine Triphosphate (ATP)-
4. Coenzymes-
VIII. MACROMOLECULES AND THEIR MONOMERS