Important Energy Source for Prokaryotic Cells - Research Proposal Example

MIC256244 If ATP is such an important energy source for prokaryotic cells, why do you think it is not routinely added to the growth medium for theseorganisms (10 pts) Hint: explanation and purposes of metabolism The Gram positive cell wall is made up of peptidoglycan and on its surface the Teichoic acids protrude out. Teichoic acids give the Gram positive cell wall an overall negative charge due to the presence of phosphodiester bonds between Teichoic acid monomers. As the lipopolysaccharides are highly charged, the Gram negative cell wall has an overall negative charge. The net charge on ATP molecule is also negative so it will not be absorbed in the cytoplasm (Pelczar, Chan and Krieg, 1986). 2. A population of a Bacillus species is growing in a soil sample. Suppose glycolysis came to a halt in these bacterial cells. Would this mean that the Krebs cycle would also stop Why or why not (10 pts) Hint: metabolism and amphibolism If the bacterium is acetate other carbon source utilizing organism, it can use glyoxylate pathway to synthesize Kreb cycle intermediates. The glyoxylate pathway converts 2-C units into 4-C units viz. Succinate. The isocitrate is cleaved into succinate and Glyoxylate by isocitrate lyase, the enzyme present in organisms using glyoxylate pathway. The other enzyme of the pathway is malate synthase which catalyse condensation of glyoxylate with the acetyl CoA to form malate. These bacteria synthesize acetyle CoA from acetate and CoA by a ATP-driven reaction catalysed by acetyl CoA synthase. (Stryer 3. Every state has an official animal, flower, or tree but Oregon has a bacterial species named in its honor: Methanohalophilus oregonese. The specific epithet oregonese is obvious, but what information can you glean from the genus name In what type of environment(s) would you expect to find this organism What are some ecological benefits of this organism (15 pts) Hint: Physical growth requirements, ecosystems The bacterium can oxidize hydrogen or formate . The electron thus generated are used to reduce carbon dioxide to methane. These are strictly anaerobic and salt loving bacteria. These are found in rich organic matter where the non methanogenic bacteria produce carbon dioxide and hydrogen. These are found in marine sediments (Pelczar, Chan and Krieg, 1986). 4. Suppose you had the choice of destroying on class of organic compounds in bacterial cells to prevent their spread. Which class would you choose Why would you choose this class Discuss the role(s) of that class of compounds within the prokaryote. (10 pts) Hint: biological polymers, cell structure, cell function Cell wall polymers such as peptidoglycan since bacterial cells divide by invagination of cell membrane followed by that of cell wall . a septum or cross wall is formed and the cell divides into two. The septum would not form when the cell lacks cell wall and its division would stop. As we have stop division of bacteria and need not kill these. Peptidoglycan is unique cell wall material found in prokaryotes only. It provides strength to withstand turgor pressure (pelczar, Chan and Krieg, 1986). 5. Patient A has a septicemia caused by a Gram(+) rod while Patient B has a bacteremia caused by a Gram(-) coccus. What extracellular structures would you expect to find on the Gram(+) and Gram(-) cells (DO NOT discuss the differences in the cell wall). What role do these appendages play in virulence and immune evasion Why might it be dangerous to treat the Gram(-) bacteremia with an antibiotic What is the difference between septicemia and bacteremia (20 pts) Hint: Cell structures, structure function, infection The extracellular structures on gram (+) and (-) bacteria may be capsules, flagella and pili or fimbriae. The pili are found on gram negative bacteria only. These help pathogenic bacteria to adhere to mucus membranes of respiratory, genitourinary or intestinal tract. The attachment prevent bacteria from being washed away by the flow of mucus or other body fluids. The capsules are viscous or gelatinous layer surrounding the bacterial cell. The capsule are polysaccharide or polypeptides. These capsule enhance virulence of pathogenic bacteria as these are resistant to phagocytosis by the white blood cells. The bacteremia is presence of pathogenic bacteria in blood and from blood these are carried to various part of body and cause localized infections. For e. g. Neisseria meningitidis can infect meninges by transient bacteremia causing severe meningitis Septicemia is a condition when infectious bacteria multiply in blood and produce toxic products. Anthrax is an example of septicemia. It might be dangerous to treat Gram (-) bacteremia with antibiotics since the lysed cell would release Lipopolysaccharides ,which are endotoxins. These endotoxins cause pyrogenicity (increased body temperature) , damage to blood platelets and increase in number of leucocytes. The blood capillary become more permeable leaking out blood causing hemorrhage. Large amount of endotoxins can cause shock whereby The feeble pulse and respiration may occur. A high dose of endotoxins can cause circulatory collapse and death (Davis et al, 1990; Pelczar, Chan and Krieg, 1986). 6. During the filming of the movie Titanic, researchers discovered at least twenty different bacterial species literally consuming the ship, especially a rather large piece of the midsection. Keeping in mind that the Titanic ship is under thousands of feet of icy waters, what type(s) of prokaryotes would you expect were at work on the ship (5 pts) Hint: physical growth requirements, ecosystems The great depth and very low temperature suggest there could be psychrohalophiles which are also barophilic. These can grow at very low temperatures and high hydrostatic pressures in salty sea water.. 7. Since the 1950s, the world has been plagued with a series of influenza viruses that differ genetically from one another. For example, we have heard of the swine flu, Hong Kong flu, Bangkok flu, and avian flu. How might the processes of transduction, coinfection, and antigenic shift help explain this variability (15 pts) Hint: Mechanisms of genetic transfer, viral infection/pathogenesis Coinfection: Although humans do not appear to be directly infected by avian influenza viruses, swine can support the replication of both human and avian viruses. Coinfection of swine by a human and an avian virus is thought to favor genetic reassortment, which may generate hybrid viruses capable of infecting humans (Sharp et al, 1997). Antigenic Shift: The two distinct from of antigenic variations occur in influenza viruses. The minor antigenic variations or drifts occur as a result of mutations in hemagglutinin and neuraminidase genes. Major antigenic variations or antigenic drift occurs infrequently and show appearance of surface antigens which are only distantly related to those on earlier strains. These major variations occur as a result of gene reassortment (e.g. recombination.) which may be between a human and animal strain (Davis et al, 1990). Transduction: During multilication of virion in the cell ,at the time of packaging of genetic material gemomes from two different virion pack instead of one. The influenza virion can take 9 -11 instead of 8 vRNA strands. Such a hybrid virion can infect to hosts and initiate infection (Davis et al, 1990).. 8. A student has finished his work in the laboratory and is preparing to leave. He remembers the instructor's precautions to wash his hands and disinfect the lab bench before leaving. However, he can not remember whether to wash first and then disinfect, or to disinfect and then wash. What advice would you give him Why would you give him that particular advice (5 pts) The student must disinfect the lab bench first and then wash his hands. Since it is not known which disinfectant he/she is using and many of these are toxic e.g. phenolic compounds (Pelczar, Chan and Krieg, 1986). 9. The necessary ingredients for mRNA synthesis can be mixed together in a test tube (in vitro), and functional RNA actually can be made. You extract the enzyme, RNA polymerase, from Bacillus subtilis and the DNA template for transcription from E. coli. If the RNA that is synthesized in vitro is then used as the mRNA for in vitro translation, will the resulting proteins be most similar to those in E. coli B. subtilis A mixture of both bacterial species' proteins Proteins that are the same as those in E. coli but only function in B. subtilis Explain why you believe your answer to be true. (10 pts) The resulting proteins would be similar to those of E.coli since mRNA is complementary to the DNA from E.coli. Whereas RNA polymerase is an enzyme,a catalyst only and does not participate in the reaction (Stryer, 2004).. . REFERENCES: Davis, B. B., Dulbecco, R., Eisen, H. N. and Ginsberg, H. R. (1990). Microbiology (4th ed.). Lippincott. Pelczar, M. J., Chan, E. C. S. and Krieg, N. R. (1986). Microbiology. McGraw-Hill International. Sharp, G. B., Kawaoka, Y., Jones, D. J. et al (1997). Coinfection of Wild Ducks by Influenza A Viruses: Distribution Patterns and Biological Significance. Journal of Virology, 71(8): 6128-6135. Stryer, L. (2004). Biochemistry Extended: Chapters 1-34. W. H. Freeman and Co. Read More