Microbiology Exam 1 study guide answers Questions and Answers correct

Microbiology Exam 1 study guide answers Questions and Answers correct What is the definition of microbiology? is the study of microorganisms and their activities. In addition, it also is the study of small living things. Microorganisms are those organisms that are too small to see with the naked eye and include things like bacteria, fungi, and viruses. What kinds of organisms do microbiologists study? Microbiologists study microorganisms. Microbiologists may specialize in the study of different groups of microorganisms. The kinds of organisms microbiologists study include: Bacteria Fungi Protists Viruses Bacteriology the study of bacteria often broadly designated as Microbiology Mycology the study of fungi Protozoology study of protozoa Virology study of viruses What are three properties of all microbial cells? Metabolism Growth Evolution Evolution Cells evolve to display new properties. Phylogenetic trees capture evolutionary relationships. Growth Nutrients from the environment are converted into new cell materials to form new cells. Metabolism Cells take up nutrients, transform them, and expel wastes. chemical transformation of nutrients. the sum of all chemical reactions that occur in a cell. What are four properties of some microbial cells that we discussed in lecture? Differentiation Communication Genetic Exchange Motility Genetic exchange Cells can exchange genes by several mechanisms. Communication Cells interact with each other by chemical messengers. Differentiation Some cells can form new cell structures such as a spore. Motility Self-movement Some cells are capable of self-propulsion. What is the 3-domain system? The 3-domain system is a system for classifying biological organisms and they include: Bacteria (prokaryotic) Archaea (prokaryotic) Eukarya (eukaryotic) Domains: three distinct lineages of microbial cells Who is the scientist responsible for developing the 3- domain system? Carl Woese Why is this gene useful for developing a phylogenetic tree of life? Phylogenetic tree: depicts phylogeny (evolutionary history) of all cells •clearly shows three domains •Root is LUCA. •evolution along two paths to form Bacteria and Archaea •Archaea diverged to distinguish Eukarya. gene must be present in all organisms What is the marker gene used to develop the 3- domain system? rRNA (ribosomal RNA sequencing) Bacteria cell structure Usually single-celled • Majority have cell wall withpeptidoglycan • Most lack a membrane-boundnucleus • Ubiquitous and some live inextreme environments • Cyanobacteria producesignificant amounts of oxygen Arachea cell structure • Distinguished from Bacteriaby unique rRNA genesequences • Lack peptidoglycan in cellwalls • Have unique membrane lipids • Some have unusual metaboliccharacteristics • Many live in extremeenvironments What is the endosymbiont hypothesis? proposes that mitochondria and chloroplasts originated as free-living bacteria that were engulfed by other microbes. Origin of mitochondria and chloroplasts from endosymbiont. Be able to correctly write out a bacteria species name. For example, Escherichia coliMust be italicized. Spelled out completely the fist time. first part uppercase and second part lowercase. After the first reference, first part can be abreviated. (ie E. coli) Who was the first person to directly observe microorganisms (yeast, fungi) ? Robert Hooke What kind of organism was engulfed to become the endosymbiont? bacteria What kind of organism did the engulfing? ancient archaea Who was the first person to directly observe bacteria? Antonie van Leeuwenhoek (). Antonie van Leeuwenhoek (): first person to observe microorganisms accurately. first to describe bacteria (Figure 1.14) Robert Hooke (): published drawings of the fungus Mucor in his book, Micrographia, in 1665. first to describe microbes (Micrographia in 1665) illustrated the fruiting structures of molds (Figure 1.13) Louis Pasteur () chemist and microscopist •Swan-neck flask' experiments •placed nutrient solution in flasks •created flasks with long, curved necks •boiled the solutions •left flasks exposed to air Results: no growth of microorganisms discovered that living organisms discriminate between optical isomers (Figure Results for Swan flask experiments by Louis Pasteur? no growth of microorganisms discovered that living organisms discriminate between optical isomers (Figure Joseph Lister (): provided indirect evidence that microorganisms were the causal agents of disease developed a surgery system to prevent microorganisms from entering wounds his patients had fewer postoperative infections Robert Koch () physician and microbiologist (Figure 1.28) experimentally demonstrated the link between microbes and infectious diseases (germ theory of infectious disease) identified causative agents of anthrax, tuberculosis, and cholera ................ postulates (Figure 1.29) awarded Nobel Prize for Physiology and Medicine in 1905 established therelationship betweenBacillus anthracis andanthrax• used criteria now knownas "Koch's postulates" (still used today toestablish the link between a particular microorganism and a particular disease) What is the germ theory of disease? Germ Theory of Disease which states that microorganisms are the cause of many diseases. What are Koch's four postulates? 1) The suspected pathogen must be present in all cases of the diesease and absent from healthy animals. 2) The suspected pathogen must be grown in pure culture. 3) Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal. 4) The suspected pathogen must be reisolated and shown to be the same as the original When and why are Koch's postulates not useful or practical? Limitations of Koch's Postulates Some organisms cannot be grown in pure culture •Using humans in completing the postulates is unethical •Molecular and genetic evidence may replace and overcome these limits What are the three important properties for imaging bacteria with a microscope? Magnification Contrast Resolution Magnification the extent to which the image of an object is larger than the object. Contrast the ability to distinguish an organism from the background. Resolution Resolution quantitative measure of the closest distance between two points at which they are clearly separate entities. Ability of a lens to separate or distinguish small objects that are close together. What is the bending of light by a lens called? Refraction What is resolution? How is it defined? quantitative measure of the closest distance between two points at which they are clearly separate entities. Ability of a lens to separate or distinguish small objects that are close together. It's one of the three important properties of a microscope What are TWO ways to improve resolution with the light microscope? 1) We can only collect SOME of the light using a lens. How can we improve resolution? Use an objective lens with a larger numerical aperture. 2. Light travels as a wave This means there is a second way we can improve resolution. Use a wavelength shorter than light. What is contrast? the ability to distinguish an organism from the background What are two general ways to improve contrast with the light microscope? Optical Techniques & Staining your Sample Optical Techniques A. Dark Field Microscopy B. Phase Contrast Microscopy Stain your sample A. Chromogenic stains• B. Fluorescence stains What is the purpose of fixation? kills the organisms and attaches them to the slide Preserves internal and external structures and fixes them in position • Organisms usually killed and firmly attached tomicroscope slide • heat fixation - routinely used withbacteria and archaea (preserves overallmorphology but not internal structures) • chemical fixation - used with larger,more delicate organisms (protects finecellular substructure and morphology) What are three functions of staining a specimen? Increases visibility of specimen • Accentuates specific morphological features • Preserves specimens What is a differential stain? • Divides microorganisms into groups based on their staining propertiese.g. Gram stain • Differential stain used to detect presence orabsence of structurese.g. endospores, flagella, capsules Different kinds of cells are different colors. What property of bacteria does the Gram stain use to differentiate bacteria? differences in cell wall structure Into how many types does the Gram stain differentiate bacteria? Divides bacteria into two groups, Gram positive and gram negative Gram negative bacteria appear pink Gram positive bacteria appear purple/violet What kind of microscopes generated the following images? (Look at Study Guide) 1) Does the Gram stain work on Archaea? you can stain archaea but it will give false reading. Some stain red, some stain purple no not really because arachea has a different cell wall structure than that of bacteria What are the two components of a Fluorescence in situ Hybridization (FISH) probe? . Reporter Component Specificity Component (Probe) Reporter component chemical dye (red dot seen in slide picture) Probe (specificity component) can be designed to attach to any sequence Cocci (s., coccus) spheres diplococci (s., diplococcus) pairs streptococci chains staphylococci grape-like clusters tetrads 4 cocci in a square Fluorescent dye -Must be conjugated to a specificity component-FISH or Fluorescence in situ Hybridization(Specificity component = DNA molecule)-Immunohistochemistry (Specificity component= Antibody) Fluorescent Protein Genetically encoded • Use molecular biology tools to conjugate the FP gene to a GENEof interest .• Allows LIVE CELL IMAGING What is the main advantage of a fluorescent protein? Allows LIVE CELL IMAGING What are the two main types of electron microscopy? The Transmission Electron Microscope (TEM) The Scanning Electron Microscope When would you use each type of microscope? The Transmission Electron Microscope (TEM)to see inside of cells. The Scanning Electron Microscope allows you to see a 3D image of the outside of the cell and structures such as flagella.