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Unformatted text preview: Version 058 Exam04 Walker (53985) 1 This print-out should have 48 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. In all cases, select the BEST response among those listed. NOTE: Recall that, in class, we corrected the textbook and learned that soy IS a complete protein. Feel free to use the web link on Blackboard to confirm for yourself after the exam. 001 5.0 points The backbone of a DNA molecule is 1. a polymer of amino acids covalently bound to one another. 2. organic bases that are hydrogen-bonded to one another. 3. a polyamide. 4. a polysaccharide. 5. a polymer of sugar and inorganic phos- phate units covalently bound to one another. correct Explanation: Definition; the bases hang off the sugar units. 002 5.0 points The excerpt below is from the April 2004 issue of the magazine Scientific American. Because hemoglobin is so well studied, sci- entists know of several mutations in its gene that are silent (cause no disease) because they substitute similar amino acids for one another. But an error that replaces a hy- drophilic amino acid with a hydrophobic one can drastically alter the resulting proteins shape or function. In sickle cell disease, a single-nucleotide mutation in the gene for hemoglobins beta chain changes the mRNA codon GAG to GUG, replacing hydrophilic glutamate with the hydrophobic amino acid valine. The resulting hydrophobic spots on hemoglobins surface are drawn to one an- other, causing the molecules to clump to- gether, producing rigid fibers that deform red blood cells into a sickle shape. The authors describe the basis for sickle cell anemia. Generalize this basis. 1. Weak intermolecular forces between seg- ments of a protein can drastically alter shape and function. correct 2. People who have an excess of hydropho- bic nucleotides in their DNA have sickle cell disease. 3. Large molecules are attracted to one an- other due to the rigidity of their fibers. 4. Changing more than one nucleotide in a sequence has a larger impact than changing only one nucleotide in that sequence. 5. Changes to a gene sequence, called muta- tions, are well studied in hemoglobin. Explanation: Sickle cell anemia is caused by the deforma- tion of red blood cells into a sickle shape. This deformation is due to the presence of anoma- lous hydrophobic areas which weakly attract each other due to anomalous variations in the protein hemoglobin. 003 5.0 points As a lawyer for a person accused of murder, you need to make the jury believe that your client is not the murderer. The prosecuting attorney has DNA evidence linking your client to the scene (Analysis of 8 segments of blood based DNA found at the scene, and on a knife found in your clients automobile.) How do you save your client?...
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- Spring '08