SQ02_Lect_4_6.ans - BioMI 290 2/3/08 Study Questions #2...

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BioMI 290 2/3/08 Study Questions #2 Lectures 4-6 (Answers) Part I. the Big Tree of Life Review Quetions #1- 1. Pure culture is having all one kind of bacteria together, with no contaminants. One isolates a pure culture by streaking bacteria on a solid surface, and picking a single colony. It was important because one cannot say for certain that a bacterium is the cause of something unless one has a pure culture to prove it. 2. Pasteur used a flask that was open to air, but that would not allow airborne contaminants to come in. With this, he was able to show that you could keep liquids sterile indefinitely if you protect them from contaminants. 3. Koch need pure cultures to prove that a given bacterium was causing a disease. He infected animals with that pure culture, and the animals got the disease, therefore, the bacteria must be the cause. Solid culture material is so important because you must be able to see individual colonies to separate them out. 4. Cohn revealed the life cycle of Bacillus and endospore formation. He also developed some aseptic techniques. 5. To satisfy Koch’s Postulates one must: 1. Observe a disease in an individual. 2. Recover, isolate and characterize the disease-causing agent from the infected individual. 3. Re-infect a healthy individual and observe similar disease symptoms. 4. Recover the same organism from the newly infected and diseased individual. Koch was the first to prove bacteria caused disease, and opened up the way for many other scientists to being proving other disease were caused by other bacteria. Beijerinck developed the concept of enrichment cultures to find new kinds of bacteria. He also discovered the first viruses (tobacco mosaic virus). Application Questions 2&3 2) see pp. 10-12 3) see pp. 12-14 Part II. Overview of Microbes 6. Size Matters! Fill in the approximate values for each of the following: Viruses range from about 20 nm to 300 nm . in size A typical prokaryote is about _0.5-10 um Bacteria and Archaea range from about 0.2 um (200 nm) to 500+ um . in size
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BioMI 290 2/3/08 Eukaryotic cells range from _5um __ to _ 150 um Your naked eye can see something about 100-200 um in siz 7. Describe the difference between a “virus” and a “virion”. A VIRUS is a non-cellular, obligately parasitic (i.e. host dependent), self- replicating genetic element consisting of DNA or RNA with no metabolic capability, but capable of transmission from host cell to host cell via a vector stage called a VIRION, in which the nucleic acid is encapsulated in a protein coat. In animal virions the protein can be covered with a membrane derived from the host cell. 8. List 5 stages in the replication cycle of a virus. Which stages require viral enzymes? Which require host enzymes and energy?
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This note was uploaded on 07/13/2008 for the course BIO 2900 taught by Professor Ghiorse during the Spring '07 term at Cornell University (Engineering School).

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SQ02_Lect_4_6.ans - BioMI 290 2/3/08 Study Questions #2...

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