Download Chemistry of Proteins Model Making

Name ________________
Date _____________
CHEMISTRY OF PROTEINS
Proteins are the main structural and growth components of cells in tissues such
as skin, hair, muscle and blood. Other proteins serve in regulatory capacity as
enzymes and hormones. Proteins always contain nitrogen in addition to carbon,
hydrogen and oxygen. Phosphorus and sulfur are also found in many proteins.
The amino acid is the basic structural unit of all proteins. There are only about
20 different amino acids known to exist in proteins; all of them have a similar
basic structure. The general structure of an amino acid is shown below:
H
H
O
N
C
C
H
R
OH
Procedure
Students will work in groups of 4. Each student will be responsible for filling out
his/her own worksheet.
1. Examine the structural formula for an amino acid drawn above.
Construct a model using your parts leaving the R portion open.
2. Note that the amino acid has an amino group (NH2) at one end
and a carboxyl acid group (COOH) at the other end. R stands
for radical (an atom or group of atoms). The uniqueness of
each amino acid is determined by the atoms in the R position.
3. The structural formulas of 3 amino acids are shown below.
Glycine is the simplest amino acid, with only a single hydrogen
atom in the R position.
4. What is the molecular formula of glycine (add correct subscripts)
C H O N
5.
What is the molecular formula of alanine?
C H O N
6.
Are the molecular formulas for all amino acids the same?
7.
Construct two different amino acids. The models constructed represent
the three dimensional shapes of the molecules.
A protein is formed by the chemical bonding of many amino acid
molecules. Proteins may contain as few as 50 or as many as 5000 or
more amino acids. The chemical combination of two amino acids is called
a DIPEPTIDE. The amino group of one amino acid molecule combines
with the acid group of another in what is called a peptide bond. In this
reaction one molecule of water is formed by the removal of a hydrogen
atom from the amino group of one amino acid molecule and an OH group
from the acid group of the other. This type of reaction is known as a
dehydration synthesis reaction.
8. Combine the two amino acid molecules you built by removing the proper –OH
group and –H group as needed to form a protein. Rejoin the –OH and –H. What
molecule do they form?
Hydrolysis is the reverse of the dehydration synthesis reaction. Water is added
and a molecule is broken into two parts.
INTERPRETATION
1.
What type of reaction is required to build carbohydrates, proteins and
fats? Explain the reaction (what needs to happen in order to put
molecules together to build bigger molecules).
2.
What type of reaction is required to break down bigger molecules into
smaller ones? Explain the reaction.
3.
What is the difference between a molecular formula and a structural
formula? Provide an example that compares the two.
4.
What are isomers? (in your own words)
5.
What two types of molecules are necessary to build a fat molecule?
6.
What type of molecule is necessary to form protein molecules? What
is a bond between two of these molecules called?