Download Organic Chemistry: Functional Groups and Nutrients Objectives

Organic Chemistry: Functional Groups and Nutrients
Objectives
Identify functional groups and what class of organic compound they are found in
Describe how proteins are made from amino acids and fats from fatty acids and glycerol
Describe what an ester is and what they are used for
So far in our study of organic chemistry, we have mentioned three classes of organic
compounds; alkanes, alkenes and alkynes. We have mentioned that compounds that share
similar features also share similar properties. There are many more. Many of these have
substituted groups that produce these properties. These substituted
groups are called functional groups. One of these functional groups is
the hydroxyl group (OH). When a hydroxyl group is attached to the
carbon chain, an alcohol is produced. You can also recognize an
alcohol by the name. Alcohol’s end in –ol. Methanol is shown. A
common name for methanol is wood alcohol and is used in industry
and is poisonous. Ethanol is from grain and can be consumed.
Another class of organic compounds is called organic acids. These contain the
functional group called carboxylic acid or the carboxyl group. The molecular formula for the
carboxyl group is COOH and the structural formula is shown
to the right. The “R” represents the carbon chain that the
carboxyl group attaches to. Notice the double bond to the
oxygen. Do not get organic acids confused with inorganic
acids such as HCl and H2SO4 (sulfuric acid). Organic acids do
not cause burns like inorganic acids can.
A third functional group is the amine group. The molecular formula for the amine group
is NH2. To the left is the structural formula. Nitrogen needs three
electrons to fill its outer level so it will form 3 bonds. The third bond (the
R) is to carbon.
Proteins are organic compounds that are made up of amino acids. Notice the name
amino acid. What are the functional groups that make up an amino acid? I hope you said an
amine group and a carboxyl group. Proteins are necessary for building and repairing of tissues
in the body especially muscle, making hormones and red blood cells. Each protein needed by
the body is composed of a different sequence of amino acids. The method the join together is
the same.
Notice the amino acid at the top. As we
previously stated is made up of two parts the
amine group and a carboxyl group. There are
approximately 20 different amino acids. What
makes the 20 different is what is in between
the two functional groups. The question is how
do we join two amino acids together. Look at
the amino acid carefully, is there any place to
attach another one. Everything has all the
electrons it needs. Now look at the “Peptide”.
It is actually a protein. The amino acid on the
left is missing the OH from the carboxyl group. The amino acid on the right is missing a
hydrogen from the amine group. To bond the 2 amino acids together, atoms are removed to
create places to bond the two together. The OH and H form water.
The formation of a fat molecule in some ways is similar to how a protein molecule
forms. Other names for fats are lipids or triglycerides. A fat molecule is made from 3 fatty
acids and one glycerol. As before, notice names- fatty acid and glycerol. Glycerol (notice –ol) is
an alcohol, notice the hydroxyl groups. Three fatty acids will join
the glycerol. Fatty acids contain a carboxyl group. Notice the shape of the 2 molecules. The
unsaturated molecule is bent at the double. This bent shape means the molecules will not be
able to be close together. Since they are not close together, they would be a liquid or at least
more liquid like. Unsaturated fats are liquid at room temperature (olive oil, corn oil, “vegetable
oil”) and saturated fats are solid at room temperature (lard, butter, bacon grease etc.). So how
would the glycerol molecule and 3 fatty acids join? Is there any atom that needs electrons to
bond the molecules together. As before with proteins something needs to be given off. The
glycerol will give of an H from the hydroxyl and from the fatty acid, OH will be released. In total
3 water molecules will form and one big lipid molecule will form. Lipids are necessary. The
provide energy. Your body stores extra fat in your body- again necessary. Some vitamins are
stored in fat and cells membrane is a lipid bi-layer.
Carbohydrates are another necessary organic molecule needed by your body.
Carbohydrates provide energy for your body- both short and long term. There are 3 categories
of carbohydrates, monosaccharaides, disaccharides
and polysaccharides. As the prefixes suggest,
monosaccharaides are made up of 1 saccharide or
sugar, disaccharides made from 2 and
polysaccharides from many. All monosaccharaides
(there are 3) have the same molecular formulaC6H12O6. But each has a different molecular
formula. Compounds like this are called isomers.
Like before, to join the monosaccharaides together,
something needs to be given off. Water is given off,
H from one and OH from another to be able to
bond monosaccharaides together.
Another category of organic compounds are called esters. Esters are made by reacting
an organic acid with an alcohol. Esters have a wide range of uses but are commonly used in
foods as artificial flavorings and they are used in both foods and cosmetics because they can
produce a pleasant odor. Both the food and cosmetic industries employee chemist to help
create the flavors and smells we enjoy.