Choose one of the three amino acids you selected that would not cause hemoglobin to form fibers if substituted for glutamic acid. Select three amino acids that could substitute for glutamic acid and would not cause hemoglobin to form fibers.ħ. Select two amino acids that could substitute for glutamic acid and, like valine, cause hemoglobin to form fibers.Ħ. Glutamic acid is negative and valine is hydrophobic.ĥ. What properties differ between these amino acids? Use the amino acid menu and color key, shown on the right. The single amino acid substitution in sickle cell anemia replaces glutamic acid with valine. They are hydrophillic because they are positive and when something is positively charged, then they attract to water.Ĥ. Which pair of amino acids in the picture above is more likely to have opposite charges: A and B, or C and D? Why?Ĭ and D because opposites attract and the two are closer together than A and B.ģ. In the picture above, where would you expect to find a water-fearing, hydrophobic amino acid: at location A, B, C, D, E or F? Why?į because it is the furthest away from all of the other molecules.Ģ. Use what you know about the structure of Hb and HbS, the properties of glutamic acid and valine, and how hydrophobicity causes molecules to behave in water.Ī Single amnio acid must be polar to attract, just like water.ġ.
Describe how a single amino acid substitution causes hemoglobin molecules to stick together. Imagine a third one randomly bouncing up to them. You've seen two Hbs molecules stuck to each other. How many amino acids in a sickle cell hemoglobin molecule are affected by the mutation?ġ. How many amino acids total make up one hemoglobin molecule?Ģ. Make many molecular changes with charge to create the shape to change.ġ. Describe a rule for making a substitution that causes a change in the shape of a protein. I made one of the molecules negative, which caused it to lean towards the left instead of the right.ģ. How did you choose a substitution that caused only a small change in the protein's shape? THe cluster did not clump nicely, infact it was more oval and spread out. How did your single substitution cause a change in the shape of the protein? Describe the substitution you made, including the properties of the amino acid you started with and the one you changed it into. Snapshot caption : The negative molecule changed the shape by having it lean towards the left instead of the upper right like model A.ġ. Snapshot caption : The hydrophilic molecule was pushed to the outside of the clump while the other molecules continued to cluster. Snapshot caption : The molecules clumped together in a cluster. At first in the oil I clustered, then in the water I spread out creating a straight chain. Describe your interactions with the solvent molecules in oil and then in water. Imagine you are one of the amino acids in the hydrophilic chain, first in oil and then in water. Describe your interactions with other amino acids and with water molecules.Īs a hydrophilic amino acid I, along with my fellow buddies, spread out so that we didn't cluster. Imagine you are one of the hydrophilic amino acids. Click on "Hydrophilic amino acids" above, and run the model. What do you experience as the chain folds in water? Describe your interactions with other amino acids and with water molecules.Īs an hydrophobic amino acid I gathered together with the fellow hydrophobic amino acids in a large cluster.Ģ. Run the model, and imagine you are one of the hydrophobic amino acids. THe blue molecules whent they were nonpolar moved around more, causing the purple molecules to not clump together easily.ġ. Once you have gotten the purple hydrophobic molecules to form clumps, set the slider to make the blue molecules non-polar. When the blue molecules were polar they made the purple molecules move around more.Ģ. What happens to the purple hydrophobic molecules? Why? Set the slider so that the blue molecules act like water molecules, then run the model. The positive and negative molecules coiled around each other due to their charge.ġ. The shape created was a circular cluster. What shape did the protein fold into when the amino acids were half positive and half negative? Explain why it folded that way, describing the interactions of amino acids with each other. THe amino acid came together in a large circular cluster as before, but took a longer time to do so.ġ. Snapshot caption : The majority of the neutral molecules are on the outside of the large cluster. Snapshot caption : The positive and negative molecules wrapped around one another to create a large coiled amino acid. My report on "Protein Folding" My report on "Protein Folding"
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