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UNIVERSITI MALAYSIA PERLIS UJIAN 2 Semester Kedua Sidang Akademik 2010/2011 March 2011 ANSWER SCHEME ERT 107 – MICROBIOLOGY FOR BIOPROCESS ENGINEERING Masa : 1 jam Please make sure that this question paper has 2 (2) printed pages including this front page before you start the examination. [Sila pastikan kertas soalan ini mengandungi DUA (2) muka surat yang bercetak termasuk muka hadapan sebelum anda memulakan peperiksaan ini.] This question paper has FOUR (4) questions. Answer ALL FOUR (4) questions. [Kertas soalan ini mengandungi EMPAT (4) soalan. Jawab kesemua EMPAT (4) soalan.] Question 1 i. For naming or grouping microorganism in Microbiology, we have the natural, phonetic, phylogenetic, and genotypic classifications. Write briefly on the best classification you would choose for the microbial taxonomy stating its advantages. ANSWER Natural classification: Arrange organisms into groups whose members share many characteristics. First such classification in 18th century developed by Linnaeus - based on anatomical characteristics This approach to classification does not necessarily provide information on evolutionary relatedness Phonetic classification Groups organisms together based on mutual similarity of phenotypes. Can reveal evolutionary relationships that compares as many attributes as possible except genetic characters Phylogenetic classification, phylogeny or phyletic classification systems Deals with evolutionary development of a species based on direct comparison of genetic material and gene products using Woese and Fox’s proposal of using rRNA nucleotide sequences to assess evolutionary relatedness of organisms. Genotypic classification Seek to compare the genetic similarity between organisms using genes or genomes and a 70% threshold of homologous genomes for prokaryotes to avoid disrupting existing species assignments. [2 advantages x10=20 marks] ii. A student was brought to the hospital to seek treatment for diarrhea, stomach pain and vomiting possibly caused by a microbe. Write the Linnaeus classification of the suspected microbe. [5 marks] ANSWER [Any one of the list below is associated with food poisoning] (Genus and species – 2 marks; Phylum, class and family – 3marks) Escherichia coli: Kingdom – Bacteria; Phylum – Proteobacteria; Class – Gammaproteobacteria; Order – Enterobacteriales; Family – Enterobacteriaceae. Salmonella enterica: Kingdom- Bacteria; Phylum- Proteobacteria; Class- Gamma Proteobacteria; Order- Enterobacteriales; Family- Enterobacteriaceae. Staphylococcus aureus: Kingdom - Bacteria; Phylum - Firmicutes; Class - Bacilli; Order - Bacillales; Family – Staphylococcaceae. Clostridium botulinum: Kingdom - Bacteria; Phylum - Firmicutes; Class -Clostridia; Order - Clostridiales; Family –Clostridiaceae. Vibrio cholerae: Domain- Prokaryota; Kingdom – Bacteria; Phylum - Proteobacteria; Class- Gammaproteobacteria ; Order- Vibrionales; Family – Vibrionaceae Aspergillus flavus: Domain – Eukaryota; Kingdom - Fungi; Phylum - Ascomycota ; Sub-Phylum – Pezizomycotina; Class –Eurotiomycetes ; Order - Eurotiales ; Family –Trchocomaceae Question 2 a) Describe the FOUR functions of plasma membrane in the cell structure of microorganisms. [20 marks] b) Classify bacteria based on the arrangement of polypeptidoglycan structure in the cell wall. [5marks] 1. 2. 3. 4. Answer a) Functions of plasma membrane separation of cell from its environment - It is the chief point of contact with the cell’s environment and thus is responsible for much of its relationship with the outside world. selectively permeable barrier – some molecules are allowed to pass into or out of the cell – transport systems aid in movement of molecules location of crucial metabolic processes such as respiration, photosynthesis, and the synthesis of lipids and cell wall constituents. detection of and response to chemicals in surroundings with the aid of special receptor molecules in the membrane b) bacteria are divided into two major groups based on cell wall arrangement Question 3 a) The Calvin cycle consists of THREE main phases that play an important role for CO2 fixation. (i) Explain the use of CO2 in cell metabolism. [10 marks] (ii) Illustrate the major molecules conversion in each phase. [15 marks] Answer (i) - CO2 is used as sole carbon source for microbes to synthesize new organelles and cells through the Calvin cycle. - CO2 will be fixed during the carboxylation phase in Calvin cycle. (ii) 1. Carboxylation phase is the addition of CO2 to ribulose-1,5bisphosphate (RuBP) catalyzes by rubisco, forming 2 molecules of 3phosphoglycerate. 2. reduction phase is the reduction of 3-phospho-glycerate to glyceraldehyde 3-phosphate 3. Regeneration phase refer to the regeneration of RuBP and the production of carbohydrates (e.g., fructose and glucose) Question 4 i. Recognize and describe the 4 factors that influence the effectiveness of the antimicrobial treatment [20 marks] ii. Describe the significance of microbial death rate in microbial control. [5 marks] ANSWER i. Several factors influence the effectiveness of antimicrobial treatment. 1. Number of Microbes: The more microbes present, the more time it takes to eliminate population. 2. Type of Microbes: Endospores are very difficult to destroy. Vegetative pathogens vary widely in susceptibility to different methods of microbial control. 3. Environmental influences: Presence of organic material (blood, feces, saliva) tends to inhibit antimicrobials, pH etc. 4. Time of Exposure: Chemical antimicrobials and radiation treatments are more effective at longer times. In heat treatments, longer exposure compensates for lower temperatures. [4pts x 5 marks=20] ii. When bacterial populations are heated or treated antimicrobial chemicals, they usually die at a constant rate. The significance of ‘microbial death rate’ is to determine the initial microbe logarithmic population and the time taken for effective sterilization. [5 marks]