Exam 2007

Exam 2007 - LS4 Final Exam-Fall 2007 Name: University ID:...

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LS4 Final Exam—Fall 2007 Name: University ID: Instructions: There are 10 problems on this exam. Each is worth 15 points. 1. Make your answers clear and concise. 2. Use the back of each sheet to work out the problems. If you need more blank paper, raise your hand and we’ll bring it to you. Try to write only your final answer on the exam question itself. Circling answers helps too. 3. Do not write in the boxes. They are for grading purposes. 4. Be sure to write your name and ID on every page. 1 point will be deducted for each page without your name. Score: Problem 1 Problem 6 Problem 2 Problem 7 Problem 3 Problem 8 Problem 4 Problem 9 Problem 5 Problem 10 Total
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Name and ID: Problem 1 On a recent trip to outer space, astronauts isolated an alien bacterium that has a similar biology to life on earth. You have been asked to determine whether or not it uses the same type of genetic code that is found on earth. One of your first observations is that while the organism uses A, T, C and G as nucleotides, there are two additional nucleotides that pair with one another, R and S. You have also studied the organism’s proteins and have concluded that there are 32 amino acids. A) What is the minimum codon length (number of nucleotides that encode an amino acid) required by these alien bacteria? (3 points) B) You clone a gene from the alien bacteria that is required for survival without oxygen. Starting with a wild-type strain of bacteria (can live without oxygen) you use acridine orange to induce a single base pair insertion into the 5’ end of this gene. The resulting bacteria can still live without oxygen. Based on this result, do you think the bacteria have an overlapping or non-overlapping code? Explain your answer. (4 points) C) You decide to further study the nature of the code by inserting a single base into the middle portion of the gene. Surprisingly, this results in bacteria that are unable to live without oxygen. Propose an explanation for this result. (4 points) D) To test your preliminary conclusions you mutate a single S in the gene to an A. You then translate the gene in vitro and sequence the resulting protein. You find that two amino acids are different in the mutant protein compared to the wild type. Does this indicate an overlapping or non-overlapping code, and how many nucleotides are used to specify an amino acid? (4 points)
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Name and ID: Problem 2 Whether the earlobe is free or attached is inherited in a simple Mendelian manner. Hanging earlobes are dominant to attached earlobes. A group of scientists is trying to identify the gene responsible for this trait by positional cloning with microsatellites. They have located a family where the mother has attached earlobes, the father has hanging earlobes, and of 12 children, 6 have attached earlobes. The results of the microsatellite analysis of the mom, dad, and 12 children are shown below. Microsatellites A and B come in two forms, A1 and A2, B1 and B2. Ee designates people with hanging
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Exam 2007 - LS4 Final Exam-Fall 2007 Name: University ID:...

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