Microbiology Notes

Microbiology Notes (Chapter 5-10) o The production of antibiotics is a form of amensalism called antibiosis. o Since one daughter cell is better at replicating than the other daughter cell, binary fission does not produce a population that doubles with every generation time. False o Contractile vacuoles are used to expel excess water from cells . o Growth factors can not be synthesized by organisms . o Which of the following microorganisms would find hypotonic conditions most detrimental? Protozoa . o A saprobe with a cell wall will utilize extracellular digestion. True . o A microaerophile requires a small amount of oxygen but won't grow at normal atmospheric levels . o When is it important to count the number of cells, determine cell size, and differentiate between dead, and live cells, a/n flow cytometer is used. o Which of the following statements is the best explanation of why communities of microorganisms in biofilms are synergic. The various microbial species can change the environment to their growth advantage, allowing all to grow better . o Most of the dry weight go a microbial cell is from organic compounds . o Cultures of a bacterial species were incubated on the shelf of a refrigerator (5 C), out on a lab bench top (22 C), on the shelf of a 37 C incubator, and on the shelf of a 50 C incubator. After incubation, there was no growth at 37 C and 50 C, slight in the refrigerator, and abundant growth on the lab bench top. What term could be used for this species. Psychrotroph . o Aerobic respiration is an example of chemoheterotrophy . o What compound has the highest concentration in a cell? H2O o The majority of microbes live and grow in habitats between pH 7 and 9. False . o Lith autotrophs use inorganic nutrients for carbon and energy sources. True . o Microorganisms require large quantities of macronutrients for use in cell structure and metabolism. o Anaerobes can be cultivated in a CO2 environment. True o The methanogens, producers of methane gas, require environments that are anaerobic with hydrogen gas and CO2 . o An organism with a temperature growth range of 45°C to 60°C would be called a/an thermophile . o Facilitated diffusion is limited by carrier proteins in the membrane. o Which of the following is not a major element of a microbial cell? copper o An organism that can use gaseous oxygen is metabolism and has the enzymes to process toxic oxygen products is a/an aerobe o Whether an organism is an autotroph or heterotroph depends on its source of nitrogen? False o Organisms that feed on dead organisms for nutrients are called saprobes . o A Coulter counter can count viable cells as well as determine the size. False o In a commensal relationship, the commensal benefits but the cohabitant is neither harmed nor benefited. True o A loopful of bacteria containing 1000 bacterial cells is inoculated into a nutrient broth and incubated. The culture was in lag phase for 10 minutes and then went into exponential log phase growth for 5 hours. The generation time for the bacterium is 15 minutes. Which equation set up is the correct one to determine how many cells at the end of the 5 hours of log phase growth. 1000 X 2^20 o Saprobes do not need a carbon source for growth and metabolism. False . o The phase of the bacterial growth curve that shows the maximum rate of cell division is the log phase . o Nutrient absorption is mediated by the cell membrane . o What statement can one make about microbial growth within food in the refrigerator? The growth of the microorganisms in the food depends on their optimal growth temperatures: some grow slow and others grow faster. o You want to experiment with microbial growth in various nutrients, so you inoculate a loopful of E. coli into a tube of honey. Which statement best describes what you expect to happen and why? The bacteria do not grow because they have been dehydrated by the honey . o An organic nutrient that cannot be synthesized by the organism and must be provided is called a/n growth factor .

o Which organism below has a problem in maintaining cellular electrolyte and fluid balance in its environment all of the above have problems in maintaining electrolyte and fluid balance within the cell o A microorganism that does not have catalase or superoxide dismutase would find it difficult to live in an environment with oxygen . o The direct cell count, using a cytometer, can calculate viable cell numbers from a sample without the use of dyes. False o Bacteria living in a freshwater stream that are moved to salty seawater would become dehydrated due to the loss of water. o An important mineral ion of the cytochrome pigments of cellular respiration is iron . o What is the difference between mutualism and synergism? In a mutualistic relationship the organisms are dependent upon each other . o Microorganisms that live in severe habitats, such as very hot, acidic, or salty environments, are called extremophiles . o The process by which a cell uses ATP to enclose a substance in its membrane, by forming a vacuole and engulfing it, is called endocytosis . o You inoculate the bacterium into 3 tubes of nutrient broth medium containing salt--0.5% NaCl, 5% NaCl, and 15% NaCl. After incubation, you notice that the organism is growing very well in the 15%, and somewhat in the 5%. There is no growth in the third tube. This organism would be called: halophilic o An organism that uses CO 2 for its carbon needs and sunlight for its energy needs is called a/an photoautotroph . o A microorganism that does not have catalase or superoxide dismutase would find it difficult to live in an environment with oxygen . o Saprobes do not need a carbon source for growth and metabolism. False o An organism that cannot grow without oxygen is a/an obligate aerobe . o Microorganisms that live in severe habitats, such as very hot, acidic, or salty environments, are called extremophiles . o The term heterotroph refers to an organism that must obtain organic compounds for its carbon needs . o Base pairs in DNA are held together by hydrogen bonds. o The enzyme that helps pack DNA into the cell by coiling the DNA into a tight bundle is DNA gyrase . o The duplication of a cell's DNA is called replication . o During replication, each parent DNA strand serves as a template for synthesis of new DNA strands. o A primer comprised of RNA is needed at the origin of nucleotide addition. o The mechanism of DNA synthesis differs between the two new daughter strands during replication. This is due to the fact that the DNA strands run antiparallel to each other and the DNA polymerase can only add nucleotides to the 3' end of the growing strand. o Which is incorrect about purines? They are only found in DNA, not in RNA. o DNA gyrase removes supercoiling ahead of origin o The site where the old DNA strands separate, and new DNA strands will be synthesized is called the replication fork o Okazaki fragments are attached to the growing end of the lagging strand by DNA ligase o DNA polymerase III synthesizes new DNA only in the 5' to 3' direction o Helicase unwinds DNA o Replication of DNA begins at a/an adenine-thymine rich area. o A gene is a specific segment of DNA that codes for the production of one functional product. o The expression of genetic traits is referred to as the organism's phenotype . o The DNA of an organism is made up of subunits called nucleotides . o The fields of genomics and proteomics differ in that genomics refers to the study of an organism's entire genome, whereas proteomics is the study of expressed proteins . o DNA Polymerase I: removes primers .