Week_6_Answers - ANSWERS TO STUDY QUESTIONS(Lectures 19-22...

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ANSWERS TO STUDY QUESTIONS (Lectures 19-22) 1) Place a labeled notch on the phylogeny where the nuclear envelope within cells is gained. There is DNA inside some of the organelles found in eukaryotes. From the DNA evidence, draw in the lineages leading to present day mitochondria and chloroplasts on the phylogeny (Chapter 28 on protists will help here). Draw a labeled circle around all the tips of the tree that belong to the bacterial group, including any appropriate organelles. Draw a labeled circle around all the tips of the tree that are prokaryotes. spirochetes cyanobacteria α -proteobacteria archaea eukarya chloroplasts mitochondria gain of nuclear envelope bacteria bacteria prokaryotes Fill in the following blanks indicating whether the specified group is paraphyletic or monophyletic: monophyletic a. Bacteria b. Archaea monophyletic c. Eukarya monophyletic d. Prokaryotes paraphyletic paraphyletic e. Photosynthetic organisms f. Organelle “organisms” paraphyletic 2) Antibiotics used to treat bacterial infections take advantage of the differences between bacteria (which are prokaryotes) and humans (which are eukaryotes). These drugs attack processes in bacteria such as cell wall formation, transcription (sometimes by interfering with RNA polymerase), and translation (sometimes by interfering with various parts of the ribosome). The success of these drugs hinges on the selective killing of bacteria (and not the human host!) With the above
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information, explain why the discovery of a disease caused by an archaeon could cause concern. Phylogenetically, archaea are more closely related to humans than are the bacteria. Specifically, the RNA polymerases and ribosomes of archaea are more similar to eukaryotic RNA polymerases and ribosomes. Indeed, some drugs that inhibit ribosomal processes in bacteria are completely ineffective on archaea. The similarity of archaeal cell components to our cell components would be the cause for worry as the trick of drug design is to find a substance that kills the pathogen and not the human host. If an archaeal disease was discovered, what part of the archaeal cell might you think about targeting with a drug? (Hint, look at Table 27.2) 3) Connect the following terms with the example that illustrates them: thermophilic autotroph heterotrophic mutualist photoautotroph halophilic phototroph A bacterium that lives near “black smokers” and it gets its carbon from inorganic compounds. A nitrogen-fixing bacterium living in plant root
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Week_6_Answers - ANSWERS TO STUDY QUESTIONS(Lectures 19-22...

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