BIOL 221 spring 2011 EXAM I

BIOL 221 spring 2011 EXAM I - Biol 221 Spring 2011...

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Biol 221 Spring 2011 NAME________________ KEY _______________________ Exam 1 [TEAR OFF THE FIRST PAGE OF THE EXAM AND HAND IT IN WITH THE SCANTRON.] Short Answer. 25 points (5 points each). 1. How do each of the following contribute to the resistance of endospores to harsh environments? On the diagram of a spore, label where you would find each of them . Peptidoglycan Spongy – soaks up water from the core to dry it out – protects against heat damage Spore Coat Dense potein – protects against UV and chemical damage – keeps from drying out too much Small Acid-Soluble Proteins (in core) DNA wrapped around these is inactive – no replication and no metabolism (+0.5 for each label and for each answer) What are the first two unique steps in endospore formation (i.e. they happen during sporulation, but nowhere else among bacteria)? asymmetric division mother cell engulfs (endocytoses) the forespore (+1 each) 2. Give a specific example of how protein primary structure influences the shape and therefore the function of a protein. (The amino acid structures are on the back page of the exam.) Then give a specific example of how protein function depends on the protein being flexible and able to move. There are many examples. The basic idea is that if an amino acid's R-group has properties that make it important for structure (-OH, -SH, -NH2, -COO-, benzene ring, etc.), and if it is replaced by an amino acid from a different class, then the structure will be changed and the protein's function will be altered. (+3) You need to cite specific amino acid changes: e.g. lysine (+ charge) changed for aspartate (- charge) and their effects (break ionic interactions) to receive full credit for this part. Examples of flexibility: rocker-switch transporters, induced fit of enzyme and substrate, rotary ATP Synthase, Flagella, Bacteriorhodopsin proton pump . . . many more. (+1 for name of protein and +1 for brief explanation of how flexibility is necessary)
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3. You have a culture of unknown bacterial cells. How would you tell if they were Gram positive or Gram negative by each of the following methods: light microscopy Gram stain – purple = G+, pink = G- electron microscopy Look for one (G+) or two (G-) membranes; Look for thin (G-) or thick (G+) peptidoglycan chemical analysis of (i.e. identifying a list of chemicals that compose) the cell wall Look for teichoic acids, glycine, or lysine in G+ cell wall chemical analysis of the cell membrane(s) Look for LPS in G- outer membrane fluorescence microscopy with fluorescent tags on a specific protein Fluorescently tag a periplasmic or outer membrane protein to demonstrate G- (e.g. porin, lipoprotein, periplasmic binding protein, Type III secretion needle complex, etc.) . (+1 each) 4. Sketch a bacterial growth curve, label the x- and y-axes, and show on the growth curve where each of the following determines the shape of the curve: A. binary fission B. persister cells C. secondary metabolism D. adaptation to new growth media
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This note was uploaded on 03/07/2011 for the course BIOL 221 taught by Professor Walter during the Spring '08 term at Purdue.

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BIOL 221 spring 2011 EXAM I - Biol 221 Spring 2011...

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