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Lesson Plan
To engage the students in learning about Villin we have designed an activity whereby the
students need to compute the molar mass of Villin.
There is a teacher’s version of the activity and there is a student’s version.
In summary, the activity requests that the students compute the molar mass of villin.
Students will have to add the molar mass of each amino acid forming the villin polymer
and subtract for the water molecules that leave the polymer as a result of peptide bonds
being formed.
This activity will be introduced after the students have built the snack model, so as to be
more familiar with the various amino acids and the villin protein.
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Claudia Winkler
Molar Mass of Villin: Teacher’s edition
Subject: High School Chemistry
California State Standard addressed as part of this activity
Conservation of Matter and Stoichiometry
3. The conservation of atoms in chemical reactions leads to the principle of conservation
of matter and the ability to calculate the mass of products and reactants. As a basis for
understanding this concept:
d. Students know how to determine the molar mass of a molecule from its chemical
formula and a table of atomic masses and how to convert the mass of a molecular
substance to moles, number of particles, or volume of gas at standard temperature and
pressure.
Organic Chemistry and Biochemistry
10. The bonding characteristics of carbon allow the formation of many different organic
molecules of varied sizes, shapes, and chemical properties and provide the biochemical
basis of life. As a basis for understanding this concept:
a. Students know large molecules (polymers), such as proteins, nucleic acids, and starch,
are formed by repetitive combinations of simple subunits.
b. Students know the bonding characteristics of carbon that result in the formation of a
large variety of structures ranging from simple hydrocarbons to complex polymers and
biological molecules.
c. Students know amino acids are the building blocks of proteins.
f.* Students know the R-group structure of amino acids and know how they combine to
form the polypeptide backbone structure of proteins.
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Claudia Winkler
Introduction
In this activity students will be asked to compute the molar mass of Villin. To complete
the activity student will have to know how to compute the molar mass of a chemical
compound and to compute percentage by mass and by number of the various amino acids
that make up villin. Students will also have to know how to account for the condensation
bonds that occur between contiguous amino acids and to subtract the molar mass of the
molecules of water that are formed in the peptide bonds.
Required time to complete activity: 2 hours
Planning time: 1 hour to make copies of students’ worksheet and a couple of overhead
transparencies
Material needed: paper, pen, calculator, periodic table
Objective:
• Knowing that villin is made of the following sequence of amino acids
DEDFKAVFGMTRSAFANLPLWKQQNLKKEKGLFMLS
1. Compute the molar mass of villin.
2. Compute the percentage by number of each atom component.
3. Compute the percentage by mass of each atom component.
Step 1:
Identify the components of each amino-acid and the number of times that each amino
acid appears in the Villin protein
D * 2 = 2 * (4*O + 4*C + 6*H+N) = 8O + 8C + 12H + 2N
E * 2 = 2* (5*C+8*H+4*O+N) = 10C + 16 H +8O + 2N
F * 4 = 4 * (9*C+11*H+N+2*O) = 36C + 44H +4N + 8O
K * 5= 5 * (6*C+14*H +2*N +2*O) = 30C + 70H +10N + 10O
A * 3 = 3 * (3 *C + 7*H+ N+ 2*O) = 9C + 21H +3N + 6O
V * 1 = 1* (5*C + 11*H + N+ 2*O) = 5C + 11H + N +2O
G * 2 = 2* (5*C + 11*H + N + 2*O) = 10C + 22H + 2N + 4O
M * 2 = 2 * (5*C+ 11*H+ N+ 2*O + S) = 10C + 22H +2N +4O + 2S
T * 1 = 1* (4 *C+ 9*H + N+ 3*O) = 4C + 9H + N + 3O
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Claudia Winkler
R * 1 = 1 * (6*C+ 14* H + 4*N + 2*O) = 6C + 14H + 4N + 2O
S * 2 = 2 * (3*C + 7*H + N + 3 *O) = 6C + 14H + 2N + 6O
N * 2 = 2 * (4*C + 8*H + 2*N + 3* O) =8C + 16H + 4N + 6O
L * 5 = 5 * (6 * C + 3 * H + N + 2 * O) = 30C + 15H + 5N +10O
P * 1 = 1 * ( 5 *C + 9 * H + N + 2 * O) = 5C + 9H + N + 2O
W * 1 = 1 * ( 11 * C + 12 * H + 2 * N + 2 * O ) = 11C + 12H + 2N + 2O
Q * 2 = 2 * ( 5 * C + 10 * H + 2 * N + 3 * O) = 10C + 20H + 4N +6 O
Step 2:
Add all carbon, oxygen, hydrogen, nitrogen, sulfur atoms.
This will lead to:
79 Oxygen atoms
198 Carbon atoms
327 Hydrogen atoms
49 Nitrogen atoms
2 Sulfur atoms
Step 3:
Account for peptide bonds that occur between amino-acids. These bonds cause
water molecules to be condensed away from the amino acid chain.
A peptide bond occurs between two adjacent pairs. There are 36 amino acids
linked by 35 peptide bonds. Each bond releases one molecule of water. A total of
35 * H2O molecules of water needs to be subtracted from the above numbers
Total number of Hydrogen atoms = 327 – 35*2 = 257 Hydrogen atoms
Total number of Oxygen atoms = 79 – 35 = 44 Oxygen atoms
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Claudia Winkler
Step 4:
Compute molar mass of Villin knowing that:
Molar mass of C = 12g/mol
Molar mass of O = 16g/mol
Molar mass of H = 1g/mol
Molar mass of Nitrogen = 14g/mol
Molar mass of Sulfur = 32 g/mol
Each molecule of Villin contains:
44 Oxygen atoms
198 Carbon atoms
257 Hydrogen atoms
49 Nitrogen atoms
2 Sulfur atoms
Each mole of Villin will contain the above number of moles of the respective
atoms. We can now compute the molar mass of one mole of Villin:
44 mol O* 16g/mol O + 198 mol C * 12 g/mol C + 257 mol H * 1g/mol H + 49
mol N * 14 g/ mol N + 2 mol S *32 g/mol = 4087 g/mol
Step 5
Compute the percentage by number of each atom component.
The total number of atoms that make up a Villin molecule can be easily obtained
adding the number of the respective Oxygen Hydrogen Carbon, Nitrogen and
Sulfur atoms:
44 + 198 + 257 + 49 + 2 = 550 atoms.
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Claudia Winkler
Percentage Hydrogen / Total atoms = 257/550 * 100 = 46.72%
Percentage Oxygen / Total atoms = 44/550 *100 = 8%
Percentage Carbon / Total atoms = 198/550 *100 = 36%
Percentage Nitrogen / Total atoms = 49/550 * 100 = 8.9 %
Percentage Sulfur / Total atoms = 2/550 *100 = .36%
Step 6
Compute the percentage by mass of each atom component.
The molar mass of a Villin mole was computed in Step 4 as 4087 g/mol
Percentage by mass of Hydrogen / Total mass = 257 mol H * 1 g/molH /4087
g/mol Villin * 100 = 6.29%
Percentage by mass of Oxygen / Total mass = 44 mol O* 16 g/molO /4087 g/mol
Villin *100 = 17.22%
Percentage by mass of Carbon / Total mass = 198 mol C * 12 g/mol C/4087 g/mol
Villin *100 = 58.14%
Percentage by mass of Nitrogen / Total mass = 49 mol N * 14 g/mol N/4087
g/mol Villin * 100 = 16.78 %
Percentage by mass of Sulfur / Total mass = 2 mol S * 32 g/mol S/4087 g/mol
Villin *100 = 1.13 %
Check for correctness by adding up all percentages:
% H = 6.29%
% O = 17.22%
% C = 58.14%
% N = 16.78%
% S = 1.13%
6.29 + 17.11+ 58.14 + 16.78 + 1.13 = 99.45 % (this is because of rounding, as
we rounded the molar masses of each element)
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Claudia Winkler
Molar Mass of Villin: Student’s activity
Objective:
• Knowing that villin is made of the following sequence of amino acids
DEDFKAVFGMTRSAFANLPLWKQQNLKKEKGLFMLS
Compute the molar mass of villin.
Compute the percentage by number of each atom component.
Compute the percentage by mass of each atom component.
Step 1:
Identify the components of each amino-acid and the number of times that each amino
acid appears in the Villin protein. The next few pages give the structure and composition
of each amino acid.
D – Aspartic Acid
Name
Aspartic acid,
Letter: D
Abbreviation:
Asp
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Info
Looks
4 oxygen
4 carbon
6 hydrogen
1 nitrogen
Claudia Winkler
E – Glutamic Acid
Name
Info
Glutamic acid
Letter: E
Abbreviation:
Glu
5 carbon
8 hydrogen
4 oxygen
1 nitrogen
Looks
F – Phenylalanine
Name
Info
Phenylalanine
Letter: F
Abbreviation:
Phe
9 carbon
11 hydrogen
1 nitrogen
2 oxygen
Looks
K – Lysine
Name
Info
Lysine
Letter: K
Abbreviation:
Lys
6 carbon
14 hydrogen
2 nitrogen
2 oxygen
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Looks
Claudia Winkler
A – Alanine
Name
Info
Alanine
Letter: A
Abbreviation:
Ala
3 carbon
7 hydrogen
1 nitrogen
2 oxygen
Looks
V – Valine
Name
Info
Valine
Letter: V
Abbreviation:
Val
5 carbon
11 hydrogen
1 nitrogen
2 oxygen
Looks
G – Glycine
Name
Info
Glycine
Letter: G
Abbreviation:
Gly
5 carbon
11 hydrogen
1 nitrogen
2 oxygen
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Looks
Claudia Winkler
M – Methionine
Name
Info
Methionine
Letter: M
Abbreviation:
Met
5 carbon
11 hydrogen
1 nitrogen
2 oxygen
1 suphur
Looks
T – Threonine
Name
Info
Threonine
Letter: T
Abbreviation:
Thr
4 carbon
9 hydrogen
1 nitrogen
3 oxygen
Looks
S – Serine
Name
Info
Serine
Letter: S
Abbreviation:
Ser
3 carbon
7 hydrogen
1 nitrogen
3 oxygen
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Looks
Claudia Winkler
W – Tryptophan
Name
Info
Tryptophan
Letter: W
Abbreviation:
Trp
11 carbon
12 hydrogen
2 nitrogen
2 oxygen
Looks
Q – Glutamine
Name
Info
Glutamine
Letter: Q
Abbreviation:
Gln
5 carbon
10 hydrogen
2 nitrogen
3 oxygen
Looks
Count all the atoms that make up villin, by element. To make this task easier, count the
individual amino-acids that make up villin and figure out how many times each of them
appears.
Knowing that villins’s sequence of amino acids is:
DEDFKAVFGMTRSAFANLPLWKQQNLKKEKGLFMLS
Identify all common amino acids and count all atoms. Show your work in a separate sheet
of paper.
Here is a hint:
D * 2 = 2 * (4*O + 4*C + 6*H+N) = 8O + 8C + 12H + 2N
E * 2 = 2* (5*C+8*H+4*O+N) = 10C + 16 H +8O + 2N.
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Claudia Winkler
Step 2:
Add all carbon, oxygen, hydrogen, nitrogen, sulfur atoms.
This will lead to:
____ Oxygen atoms
____ Carbon atoms
____ Hydrogen atoms
____ Nitrogen atoms
____ Sulfur atoms
Step 3:
Account for peptide bonds that occur between amino-acids. These bonds cause
water molecules to be condensed away from the amino acid chain.
A peptide bond occurs between two adjacent pairs. There are 36 amino acids
linked by 35 peptide bonds. Each bond releases one molecule of water. A total of
____ * H2O molecules of water needs to be subtracted from the above numbers
Total number of Hydrogen atoms = ____
Total number of Oxygen atoms = ____
Step 4:
Compute molar mass of Villin knowing that:
Molar mass of C = ____
Molar mass of O = ____
Molar mass of H = ____
Molar mass of Nitrogen = ____
Molar mass of Sulfur = ____
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Claudia Winkler
Each molecule of Villin contains:
____ Oxygen atoms
____ Carbon atoms
____ Hydrogen atoms
____ Nitrogen atoms
____ Sulfur atoms
Each mole of Villin will contain the above number of moles of the respective
atoms. We can now compute the molar mass of one mole of Villin:
____________________________
Step 5
Compute the percentage by number of each atom component.
The total number of atoms that make up a Villin molecule can be easily obtained
adding the number of the respective Oxygen Hydrogen Carbon, Nitrogen and
Sulfur atoms:
____
Percentage Hydrogen / Total atoms = ____
Percentage Oxygen / Total atoms = ____
Percentage Carbon / Total atoms = ____
Percentage Nitrogen / Total atoms = ____
Percentage Sulfur / Total atoms = ____
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Claudia Winkler
Step 6
Compute the percentage by mass of each atom component.
The molar mass of a Villin mole was computed in Step 4 ____
Percentage by mass of Hydrogen / Total mass = ____
Percentage by mass of Oxygen / Total mass = ____
Percentage by mass of Carbon / Total mass = ____
Percentage by mass of Nitrogen / Total mass = ________
Percentage by mass of Sulfur / Total mass = ____
Check for correctness by adding up all percentages:
% H = ____
% O = ____
% C = ____
% N = ____
% S = ____
Is your total equal 100%? Discuss reasons possible sources of error if your total
sum differs from 100 by more than 2%.
What did you learn in this lab?
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Claudia Winkler