Micro Exam 2 Study Guide
Micro Exam 2 Study Guide BIO 2200 (Microbiology, Dr. Thomas Roberts)
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BIO 2200 (Microbiology, Dr. Thomas Roberts)
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This 4 page Study Guide was uploaded by Taylor Notetaker on Wednesday February 24, 2016. The Study Guide belongs to BIO 2200 (Microbiology, Dr. Thomas Roberts) at Wayne State University taught by Dr. Thomas Roberts in Winter 2016. Since its upload, it has received 111 views. For similar materials see Microbiology in Biological Sciences at Wayne State University.
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Date Created: 02/24/16
Exam 2 Study Guide Macronutrients: nutrients required in large amounts Types carbon, nitrogen, phosphorus, sulfur, potassium, magnesium, calcium, sodium, & iron Know key features of each type of macronutrient Micronutrients: nutrients required in trace amounts Pure culture: a culture containing only 1 type of microbe Goal Techniques streak plate, pour plate, & spread plate Types of media: Culture media o Types defined & complex Enriched media Selective media o Ex: NaCl Differential media Free energy of formation is the energy that is released from something. Chemical energy released in redox reactions is stored in phosphorylated compounds ATP, phosphoenolpyruvate, glucose 6-phosphate, coenzymeA 2 reactions are linked to energy conservation in chemoorgranotrophs fermentation & respiration. Respiration generates more ATP while fermentation occurs when conditions are anoxic Binary fission is mitosis for bacterial cells. Min proteins act as the GPS for the components of Fts. It helps FtsZ find the middle of the cell. FtsZ ring is part of the divisome. Divisome is a combo of Zip, FtsZ, & FtsA. The divisome is shown the middle of the cell by the min proteins. DNA is the 1 to be replicated, followed by the septum, then the cell wall. FtsK proteins function similar to spindle fibers. ZipA connects the FtsZ ring to cytoplasmic membrane. MreB forms simple cytoskeleton in Bacteria & Archaea. Localizes synthesis of new peptidoglycan & other cell wall components to specific locations along the cylinder of a rod shaped cell during growth. Cocci cell wall grows in opposite directions outward from the FtsZ ring Rod shaped cells growth occurs at several points along length of the cell Steps involved in cell division (in order): autolysin activity, bactoprenol, glycolase, transglycolase, and transpeptidation Bactoprenol: carrier molecule that plays a major role in insertion of peptidoglycan precursors Glycolase: insert cell wall precursors into growing points of cell wall Transpeptidation: forms the peptide cross links between muramic acid residues in adjacent glycan chains o Links M & G to the row above Generation time is dependent on growth medium & incubation conditions . Typical growth curve for population of cells grown in a closed system is characterized by lag, exponential, stationary, & death phase. Lag phase: interval between inoculations of a culture & beginning of growth ; # of new cells equals the # of dying cells Exponential phase: bacteria doubles numbers every generation period; point where bacteria knows environment *healthy state * Stationary phase: growth rate of population is 0; death equals reproduction Death phase: more death than reproduction; cells die if incubation continues In a chemostat - growth rate is controlled by dilution rate - growth yield is controlled by concentration of the limiting nutrient - cultures are sensitive to the dilution rate & limiting nutrient concentration Limitations of microscopic count: - can’t distinguish between live & dead cells without special stains - small cells can be overlooked - precision is difficult to achieve - phase contrast microscope required if a stain isn’t used - cell suspension of low density are hard to count - motile cells need to be immobilized - debris in sample can be mistaken for cells microorganism can be classified into groups by their growth temperature optima. - Psychrophile o Ex: polaromonas vaculolata o 0 degrees Celsius - Mesophile * prime living conditions* o Ex: E. Coli - Thermophile o 80 degrees Celsius o Geobacillus Stearothermophillus - Hyperthermophile o 100 degrees Celsius o Thermococcus celer The closer you are to the minimum temperature, the slower the growth rate will be, whereas at the maximum temperature, everything dies. Above 65 degrees Celsius, only prokaryotic life forms exist. Prokaryotes are able to grow at higher temperatures than eukaryotes. Organisms with the highest temperature optima are Archaea. Nonphototrophic organisms can grow at higher temperatres than phototrophic organisms. Acidophiles –pH>6 - membranes are destroyed at neutral pH Alkaliphiles –pH< 8 Positive water balance: when a cell is in an environment with higher external solute concentration, water will flow out unless the cell has a mechanism to prevent it. Aerobes: require oxygen to live Anaerobes: don’t require oxygen & may even be killed by exposure Aerotolerant anaerobes: can tolerate oxygen & grow in its presence even though they can’t use it Facultative anaerobes: can live with or without oxygen Microaerophiles: can use oxygen only when its present at levels reduced from that in air Toxic forms of oxygen formed in the cell: single oxygen, superoxide anion, hydrogen peroxide, hydroxyl radical. Enzymes used to neutralize the toxic oxygen species: catalase, peroxidase, superoxide dismutase, superoxide reducatase Bacteriostatic: won’t allow for growth & won’t kill it Bactericidal: kills it & stops growth Bacteriolytic: kills the cell by popping it (MIC) Minimum inhibitory concentration: small amounts of an agent needed to inhibit growth of a microorganism - uses liquid media Disc diffusion assay uses solid media. Antimicrobial agents can be divided into 2 categories - products used to control microorganisms in commercial & industrial applications - products designed to prevent growth of human pathogens in inanimate environments & on external body surfaces 3 informational macromolecules: DNA, RNA, proteins genetic information flow can be divided into 3 stages - replication: DNA is duplicated - transcription: info from DNA is transferred to RNA (mRNA, tRNA, rRNA) - translation: info in RNA is used to build polypeptides Negative supercoiling: double helix is underwound - found in nature transposable element is inserted into other DNA molecules - 3 types insertion sequences, transpoons, & special viruses
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