Prelab assign 2 & 3

Prelab assign 2 & 3 - PRE-LAB ASSIGNMENT FOR LAB...

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PRE-LAB ASSIGNMENT FOR LAB EXERCISES #2 and #3 PRE-LAB ASSIGNMENT: Read the background information and complete all of the activities. This entire assignment is due at the beginning of Lab #2: Microbes: Good or Bad . OBJECTIVES: By the end of this pre-lab assignment, students will be able to… Convert between nm, µ m, and mm and L, ml, and µ l. Describe the size differences among microorganisms and other cells. Compare and contrast prokaryotes, eukaryotes, and viruses. Describe the extent to which prokaryotes dominate life on earth in terms of number of organisms. Describe the birth of the compound light microscope and how it changed our understanding of life on earth. Make serial dilutions and understand the math necessary to do so. You will need a cm ruler to complete this assignment. Metric rulers can be obtained at the Bookstore. BACKGROUND INFORMATION: What are microbes? Last week, you had a chance to make observations about a microbe called Erwinia carotovora. You saw how this infectious agent caused a disease in potatoes known as “soft rot.” You determined it was the causal agent using Koch’s Postulates. But, were you certain at the time whether this causal agent was a bacteria, fungus, virus, of protozoa. It wasn’t until the invention of the microscope around 1590 that scientists were even able to see the world of microbes. But, once they were, then there was a need to understand more about the similarities and differences among these microorganisms. Question: Using information from last week’s lab, compare the dates of the invention of the microscope and the work of Koch. What other progress was made in the world of science between these two dates? What were scientists doing? (Sadava, 4-5) You might have learned that cells and/ or microbes (remember, most microbes are cells) can be prokaryotic or eukaryotic cells. The three domains include Bacteria, Ar chaea , and Eukarya. Question: Briefly, what is the difference between Bacteria, Archaea , and Eukarya, (Sadava, 11- 12, 562) What is a virus? Viruses range in size from 20 - 300 nm. Viruses can replicate themselves only by infecting a host cell. They therefore cannot reproduce on their own. At the most basic level, viruses consist of genetic material contained within a protective protein coat. They infect a wide variety of organisms: both eukaryotes (animals, plants, protists, and fungi) and prokaryotes ( Bacteria a nd Archaea ). A virus that infects bacteria is known as a bacteriophage , often shortened to phage . For convenience, we will refer to a virus as a microbe in this exercise. Question: It has been argued extensively whether viruses are living organisms. Most virologists consider them non-living, as they do not meet all the criteria of the generally accepted definition of life. Would you classify them as living or non-living or does it matter at all? (Sadava, 283)
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This note was uploaded on 04/07/2008 for the course BIOSCI 0050 taught by Professor Carollafarve during the Fall '07 term at Pittsburgh.

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Prelab assign 2 & 3 - PRE-LAB ASSIGNMENT FOR LAB...

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