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1

Micro Lecture take home 2
1) One that has high G+C % content will be more likely related
2) What evidence is used to determine the plylogeny of prokaryotes? Due to few mutations, rRNA genes applied with rRNA sequencing and DNA hybridization are used as evidence to determine the phylogeny of prokaryotes
3) Explain the rationale for using molecular data for classification, in place of morphology. Many microorganisms look too similar to be classified by their structures or morphology. Through a microscope, organisms that might differ in metabolic or physiological properties may look alike. Literally hundreds of bacterial species are small rods or small cocci; therefore, more rationale to use molecular data for classification.
4) What is the competitive advantage provided by attaching to a surface? In low-nutrient aquatic environments, such as lakes, members of the genus Caulobacter feature stalks that anchor to surfaces. This arrangement increases their nutrient uptake because they are exposed to a continuously changing flow of water and because the stalk increases the surface-to-volume ratio of the cell. Also, if the surface to which they anchor is a living host, these bacteria can use the host’s excretions as nutrients. When the nutrient concentration is exceptionally low, the size of the stalk increases, evidently to provide an even greater surface area for nutrient absorption.
5) A teenaged male in California complained of remittent fever, chills,and headaches. A blood smear revealed ring-shaped cells in his red blood cells. He was successfully treated with primaquine and chloroquine. The patient lives near the San Luis Rey River and has no history of foreign travel, blood transfusion, or intravenous drug use. What is the disease? How was it acquired? The ring-shaped cells in the red blood cells is evidence the teenage male contracted malaria. By living near the river which are breeding grounds for Anopheles mosquitoes carrying the infective stage of Plasmodium, called sporozoite, bites the teenage male. Sporozoites was then injected into him. The sporozoites undergo schizogony in liver cells and produce thousands of progeny called merozoites, which infect red blood cells. The young trophozoite looks like a ring in which the nucleus and cytoplasm are visible. This is called a ring stage. The red blood cells eventually rupture and release more merozoites. Upon release of the merozoites, their waste products, which cause fever and chills, are also

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2

O1) One of the advantages of some newly developed rapid identification tools is that pure cultures are not needed. Why is a pure culture necessary for biochemical tests such as the Enterotube, but not for DNA probes?
For biochemical tests, such as the Enterotube, if the culture contains any unwanted organisms, it could skew the results of the biochemical test potentially producing false-positive or false-negative results of the test. You use the Enterotube test to find one unknown microorganism; therefore, if you don't use a pure culture, you don't know for sure what microorganism you identified with your results. On the other hand, when and microorganism is difficult to culture/grow you use a DNA probe. DNA probes bind directly to predefined nucleic acid sequences, which basically identifies the microorganism even when surrounded by other microorganism's. Therefore, a pure culture is unnecessary.

2) Name two diseases that may be diagnosed by Western Blotting.
Lyme disease, HIV, Bovine spongiform encephalopathy, Hepatitis B.

3) The use of culture-independent techniques has increased our understanding of microbial diversity without cultivation. Therefore, do microbiologists still need to attempt to grow new microbial species? Explain.
Man of the microbes that exist cannot be cultivated by conventional methods on conventional growth media and have remained unknown. IN recent years, however, isolation and identification methods have become much more sophisticated, and microbes that fill these niches are being identified - many without being cultivated. Until now, microbiologists have identified and described only about 5000 bacterial species, of which about 3000 have been listed in Bergey’s Manual. The true number may be in the millions. One report indicates that a single gram of soil may contain 10,000 or so bacterial types, so yes. Microbiologists need to attempt to grow many more microbial species.

4) Bacteroides and Escherichia are both gram-negative rods found in the large intestine. Why are they in different phyla?
The gammaproteobacteria species Escherichia coli is one of the most common inhabitant of the human intestinal tract and is probably the most familiar organism in microbiology. Its presence in water or food is an indication of fecal contamination. It’s not usually pathogenic, however, it can be a cause of urinary tract infections and certain strains produce enterotoxins that cause diarrhea and occasionally cause very serious f

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