The Chemistry of Proteins
Name ________________________
Period _____ Date ______________
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:
The general structure of an α-amino acid, with the amino group on the left and the carboxyl
group on the right.
Procedure:
Students will work in groups no larger than 2.
Each student will be responsible for filling out his/her own worksheet.
Each group needs:
9 (carbon – C) = black pieces
7 (oxygen – O) = red pieces
20 (hydrogen – H) = yellow pieces
3 (nitrogen – N) = blue pieces
35 wood bonds (used for single bonds)
6 spring bonds (used for double bonds)
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.
Gly = Glycine
H2N-CH2COOH
Ala =Alanine
Thr = Threonine
CH3CH(NH2)COOH
CH3CH(OH)CH(NH2)COOH
4. What is the molecular formula of (add the correct subscripts below):
Glycine
Alanine
C
H
O
N
C
H
O
N
C
Threonine
H
O
N
5. Are the molecular formulas for all three amino acids the same? _________________
6. 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 -H 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.
●
7. 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. Why is the process of making proteins known as a dehydration synthesis reaction?
2. What type of molecule is necessary to form protein molecules?
The Chemistry of Proteins
Name ANSWER KEY
Period _____ Date ______________
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:
The general structure of an α-amino acid, with the amino group on the left and the carboxyl
group on the right.
Procedure:
Students will work in groups no larger than 2.
Each student will be responsible for filling out his/her own worksheet.
Each group needs:
9 (carbon – C) = black pieces
7 (oxygen – O) = red pieces
20 (hydrogen – H) = yellow pieces
3 (nitrogen – N) = blue pieces
35 wood bonds (used for single bonds)
6 spring bonds (used for double bonds)
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.
Gly = Glycine
H2N-CH2COOH
Ala =Alanine
Thr = Threonine
CH3CH(NH2)COOH
CH3CH(OH)CH(NH2)COOH
4. What is the molecular formula of (add the correct subscripts below):
Glycine
Alanine
C 2 H 5 O 2 N
C 3 H 7 O 2 N
Threonine
C 4 H 9 O 3 N
5. Are the molecular formulas for all three amino acids the same? No
6. 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 -H 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.
●
7. 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?
Water
Hydrolysis is the reverse of the dehydration synthesis reaction. Water is added and a
molecule is broken into two parts.
Interpretation
1. Why is the process of making proteins known as a dehydration synthesis reaction?
Water is removed when the amino acids are joined to make a protein.
2. What type of molecule is necessary to form protein molecules?
Amino acids