Name _____________________________ Period ______ Date _________________
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Lab: Protein Folding
In humans, the hemoglobin protein is responsible for the transport of oxygen gas. One form of
hemoglobin, hemoglobin S, leads to sickle-cell anemia. The first reports of symptoms from disease date
back to the 1670s from stricken families in the West African country of Ghana. In 2010, it is estimated
that 29,000 people died of this disease. Three-quarters of these deaths occurred in Africa. This heritable
disease is a result of an amino acid substitution of glutamic acid to valine in the hemoglobin protein.
Amino acids differ in groups their R. These R groups are critical to the role proteins play in the body. In
this lab, you will investigate the impact of the amino acid substitution that leads to sickle-cell anemia.
Below is a diagram showing the effects of sickle-cell anemia on the structure of the red blood cells.
Directions and Activity Questions
1. Assign leader, materials manager, reader, and speaker roles in your group. While working in groups,
fold a toober into a 3-dimensinal globular shape (your teacher will demonstrate). Please be careful
with the toobers. Draw a general pattern of your folded toober in the normal hemoglobin box on
Page 2 (2 points).
2. To make a stable protein, use the information below to insert 12 push pin into the toober. Each
push pin represents an amino acid.
White = positive (+) R group – will be attracted to the negative (-) R groups
Black = negative (-) R group – will be attracted to the positive (+) R groups
Red = non-polar (NP) hydrophobic R groups – these will be buried on the inside of the protein,
where they are hidden from polar water molecules.
Blue = polar (P) hydrophilic R groups – will be on the outer surface where they can form
hydrogen bonds with water.
Name _____________________________ Period ______ Date _________________
3. Without removing the push pins, carefully follow the structure of your protein and list the amino
acids in order, left to right, using these simplified notations: + (for positive), - (for negative), NP (for
non-polar), P (for polar). Write that list in the top row of the chart below (1 point):
4. Using the chart of amino acids provided at each desk, match each +, -, NP and P listed above to the
name of an amino acid that it could be and use glutamic acid at least once. Using the abbreviations
for the amino acids, write the amino acids below each symbol (+, -, NP, or P) in the above chart.
You may use the same amino acid name more than once (1 point).
5. Normal hemoglobin is a globular protein similar to the structure you created. As their name implies,
they form globs, unlike linear proteins that form other structures . To make hemoglobin S, unfold
your protein and replace glutamic acid (a negatively charged amino acid) with valine (a nonpolar
amino acid). Then refold your protein into a stabile shape by following the rules above. Sketch a
drawing of sickle-cell hemoglobin below (2 points).
Normal Hemoglobin
Sickle-cell hemoglobin
7. How is a ball rolling downhill like a protein folding? Reference rules you followed to fold your
protein from 2 above (2 points).
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8. How did the shape of the protein change with the substitution (2 points)?
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9. Red blood cells are full of hemoglobin. How does the amino acid substitution change in hemoglobin
impact the structure and flow of red blood cells? What is the resulting impact on a sickle-cell anemia
patient’s health? Reflect on this activity and utilize outside resources to complete your answer. Cite
source used in MLA format. Refer to and underline amino acid side chains, energy, hydrophobic,
sickle-cell anemia, and stability in your response (6 points).
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Source: ______________________________________________________________________________