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1 Scientific Method:How to approach a problem scientifically: observe an event in a questioning manner, generate a testable hypothesis, design repeatable experiments to test the hypothesis 1.Observation- objective (can be verified)/subjective (may not be interpreted in the same way by different people); subjective observations must be transformed into objective observations in a lab 2.Hypothesis- tentative explanation of cause and effect; cause: independent variable/effect: dependent variable; only test ONE variable What does a hypothesis entail? 3.Experiment- tests a hypothesis; independent variable = altered but everything else stays consistent; include a control; you cannot prove a hypothesis but accept it with some level of confidence How to employ the scientific method: work with a group, follow a list of materials/methods, create/follow the protocol and collect data, record data 2 Microbes: How Clean is Clean: Function of a gram stain: used to place bacteria into one of two groups: gram positive (stain violet) OR gram negative (stain red)*Bacteria that retain the initial crystal violet stain (purple) are said to be "gram-positive," whereas those that are decolorized and stain red with carbol fuchsin (or safranin) are said to be "gram-negative." This staining response is based on the chemical and structural makeup of the cell walls of both varieties of bacteria. Bacteria = examined by streaking a sample of the bacteria on Petri plates filled with agar-based media on which bacteria can grow Agar= a polysaccharide compound located in the cell walls of some red algae Experiment to test the effectiveness of different methods of reducing microorganisms in the environment Draw/describe experiment: 3 domains: Archaea, Bacteria, Eukarya
Prokaryotes (archaea, bacteria):unicellular, no membrane bound organelles, mainly asexual reproduction, feeding is accomplished mostly by absorption Our focus: Domain Bacteria two groups we examined: Bacteria:very abundant in the soil, play an important role in nitrogen fixation(convert nitrogen from the atmosphere to nitrogen that can be used by plants), important decomposers, used in the production of some foods. TWO types of autotrophic bacteria:1.Photosynthetic- use light as their energy source, differ from plants in that water = NOT the source of electrons, also their pigments possess a different structure and they lack chloroplasts2.Chemosynthetic- obtain their energy from the oxidation of inorganic substances 3 major types of bacteriabased on SHAPE: bacilli (rods), cocci (spheres), spirilla (corkscrews)Cyanobacteria OR blue-green algae:all blue-green algae = photosynthetic, possesses the pigment chlorophyll a (located ON membranes throughout cytoplasm) and utilize water in their photosynthetic process (therefore, O2is a byproduct), some capable of nitrogen fixation, occur in unicells or colonies.