Micro Exam 1 Study Guide
Micro Exam 1 Study Guide 81383 - MICR 3050 - 002
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This 9 page Study Guide was uploaded by Stephanie Erickson on Sunday January 31, 2016. The Study Guide belongs to 81383 - MICR 3050 - 002 at Clemson University taught by Krista Barrier Rudolph in Fall 2015. Since its upload, it has received 114 views. For similar materials see General Microbiology in Biological Sciences at Clemson University.
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Date Created: 01/31/16
UNIT 1 STUDY GUIDE Spring 2016 MICR 3050 OBJECTIVES: Chapter 1 1. Define “microorganism” and describe the types studied by microbiologists (cellular and acellular). a. Microorganism: organisms and acellular entities too small to be clearly seen by the unaided eye (generally less that 1mm in diameter) b. Cellular: consisting of living cells (bacteria, humans) c. Acellular: lacking cells (viruses) 2. Understand the importance of microorganisms (scope and relevance). a. Most populous and diverse group of organisms b. Play a major role in recycling essential elements (carbon, nitrogen, oxygen, and sulfur) c. Good source of nutrients (contain 50% of Earth’s carbon) d. Excellent tools for study 3. Compare and contrast prokaryotic and eukaryotic microbial cells. a. Prokaryotes i. Lack true membranebound organelles ii. No nucleus – only nucleoid region iii. Normally single celled iv. Cell wall contains peptidoglycan (bacteria) v. No meiosis vi. Smaller in size (0.22mm) b. Eurkaryotes i. Have membranebound organelles ii. Have a nucleus iii. Multi cellular iv. Cell wall does not contain peptidoglycan v. Sex reproduction involves meiosis vi. Larger in size (10100mm) 4. Explain how the Universal Phylogenetic Tree was developed. a. Isolate DNA b. Perform PCR (polymerase chain reaction) c. Compare DNA sequences and count # of unmatched sequences d. # unmatched/total genes X 100 = % evolutionary distance e. The lower the percentage, the more closely related the species are – more closely positioned on the tree f. Lines have to do with relatedness, not time 5. Distinguish between the three domains of life and explain their relatedness. a. Bacteria i. Prokaryotes – lack nucleus and membrane bound organelles ii. Singlecelled iii. Cell wall with peptidoglycan b. Archaea i. Prokaryotes – lack nucleus and membrane bound organelles ii. Singlecelled iii. Lack peptidoglycan in cell walls iv. Have unique membrane lipids c. Eukarya i. Have nucleus and membrane bound organelles ii. Generally larger than bacteria or archaea iii. Unicellular or multicellular 6. Describe the microorganisms of the three domains. a. Bacteria i. Singlecelled ii. Cell wall contains peptidoglycan iii. Abundant in soil, water, air, and in/on other organisms iv. Beneficial in breaking down dead plant and animal material b. Archaea i. Prokaryotes ii. Lack peptidoglycan in cell walls iii. Unique rRNAsequences iv. Have unique membrane lipids v. Live in extreme conditions c. Eurkarya i. Eukaryotes 1. Protises a. Generally larger than most bacteria and archaea b. Unicellular 2. Yeast a. Unicellular 3. Mold a. Multicellular 7. Be familiar with the current theories of microbial evolution and the evidence used to support these theories. a. Mutation of genetic material causes new genotypes, if the genotypes results in a new phenotype, and the phenotype allows the for better survival within an environment the individual with the mutation is more likely to reproduce – eventually causing the species to change 8. Define the prokaryotic “species” and the bacterial strain. a. Species: a collection of strains that share many stable properties and differ significantly from other groups of strains b. Strain: consists of the descendants of a single, pure microbial culture 9. Explain how microorganisms are named. a. Genus first species second b. Both are italicized, the genus is capitalized c. Cocci – sphere shapes d. Bacilli – rodshaped e. Spirilli – spiral shaped 10. Know the contributions of the scientists discussed to the science of microbiology. a. Robert Hooke i. Coined term “cell” ii. Found blue mold on shoe leather iii. First to publish drawings of microorganisms in scientific drawing b. Leeuwenhoek i. Made microscopes (30300x magnification) ii. First to observe and accurately describe bacteria (thought they were small animals) 11. Explain the theory of Spontaneous Generation and explain how it was disproved. a. Spontaneous generation: living organisms can develop from nonliving or decomposing matter b. Required several scientists to disprove i. Francesco Redi (1668) 1. Discredited spontaneous generation for large animals 2. Steak and in jars (sealed or unsealed) experiment ii. Louis Pasteur (1861) 1. Used Pasture flask which had long neck to prevent microbes from entering iii. John Tyndall (18201893( 1. Demonstrated that dust carried microorganisms using box coated in glycerine 2. Discovered heatresistance bacteria iv. Ferdinand Cohn 1. Discovered bacteria form endospores when conditions are poor; these activate and germinate when condition improve 2. Endospore: dormant version of a bacteria that can survive extreme conditions 12. List Koch’s Postulates and describe how they are used to determine the cause of a disease (including the microbiological techniques employed). a. Establish the relation between a particular microorganism and a particular disease i. The suspected pathogenic organism should be present in all cases of the disease and absent form healthy animals ii. The suspected organism should be grown in pure culture iii. Cells from a pure culture of the suspected organism should cause disease in a healthy animal iv. The organism should be reisolated and shown to be the same as the original b. Koch used agar and petri dishes i. Agar: useful because it doesn’t melt at body temp ii. Petri dishes: have airways for oxygen to enter iii. Streaking helps a pure culture grow on the agar plate 13. Be aware of the major fields in microbiology and various job opportunities in these fields. a. Immunology i. Produce vaccinations b. Industrial Microbiology i. Perform pasteurization to prevent bacteria from spoiling food products c. Microbial Ecology i. Use enrichment cultures and selective media ii. Study soil d. Molecular Microbiology i. Study DNA and genetic alteration ii. Perform PCR Chapter 2.1 – 2.4 14. Know the terms associated with microscopy. a. Brightfield microscope: light is used to illuminate an image; specimen shows up dark with a bright background b. Darkfield microscope: image is formed by light reflected or refracted by the specimen; produces a bright image ob the object against a dark background c. Electron microscope: uses electrons instead of light as the illuminating beam i. Transmission EM: show cross section ii. Scanning: show 3D images d. Focal point – point where all the light rays are focused e. Focal length – distance between the center of the lens and the focal point f. Parfocal – lenses stay in focus when you increase the objective g. Parcentric – center of the images stays in the center as you increase the objective 15. Define and understand the concepts of magnification, resolution, and refractive index (including the factors that affect them and how). a. Magnification – enlarge the image of something i. Affected by focal length 1. Shorter focal length = greater magnification ii. For brightfield microscopes, magnification is limited by the resolutions (anything above 1500x becomes too blurry) b. Resolution – ability of a lens to separate or distinguish between small objects that are close together i. Resolution Equation 1. d = 0.5(wavelength)/NA ii. Affected by wavelength 1. Decrease wavelength = greater resolution a. Use blue light iii. Affected by numerical aperature (NA) 1. Higher NA = greater resolution 2. NA = nsin θ 3. Increase NA by increase n (refractive index) or θ (angle at which light hits the specimen a. Increase n by using oil b. Increase θ by shortening the working distance c. Refractive index – measure of how greatly a substance slows the velocity of light i. How much light bends when it hit a different substance depends on the refractive indices of the media forming the interface 16. Describe the attributes and limitations of the microscopes discussed and how they are used. a. Brightfield i. Limited resolution ii. Requires staining b. Darkfield i. Good for observing internal structures ii. Great for observing motility iii. Can observe living specimens, unstained c. Electron Microscope i. Greater for extremely high magnification ii. Requires a vacuum and metal staining 17. Compare and contrast light and transmission electron microscopes. a. EMs use electrons instead of light as the illuminating beam b. EM have much higher resolution because the wavelength of the electron beam is much shorter than light c. EM images must be obtained in a vacuum so air particles don’t disturb electron beam 18. Explain the preparation and staining of specimens. a. Staining increases visibility of specimen b. Accentuates specific morphological features c. Preserves specimens by denaturing the enzymes d. Fixation – preserves specimens and fixes them in position i. Heat fixation – fixed to the slide using high heat; preserves overall morphology, may distort appearance of internal structures ii. Chemical fixation – fixed using chemical substance (such as formaldehyde); used with larger, more delicate organisms, can preserve morphology and internal structures e. Staining – makes internal and external structure of cell more visible by increasing contrast with background i. Chromophore group – chemical group that give dye its color ii. Ability to bind to cells 19. Compare and contrast the characteristics of basic and acidic dyes. a. Basic dyes i. Dyes with positive charge ii. Bind to negatively charged structured b. Acidic dyes i. Dyes with negative charge ii. Bind to positively charged structure c. Mot bacteria have a negative charge on their surface, so commonly we use basic dyes in the lab 20. Distinguish between simple staining, differential staining, and negative staining. a. Simple staining: a single staining agent is used b. Differential staining: 21. Know the steps of the Gram stain and understand how it differentiates gram positive and gramnegative bacteria. 22. Describe the acidfast stain, endospore stain, capsule stain, and flagella stain. Chapter 7.5 23. Compare and contrast defined and complex media. a. Defined media: all components and their concentrations are known (the exact chemical formulas b. Complex media: media contains some ingredients of unknown or concentration i. Ex: beef extract, agar, soil, peptones, pancreatic juices 24. Distinguish between general purpose, enriched, minimal, selective, and differential media. a. General purpose media: supports the growth of many microorganisms, all you can tell is a basic colony morphology i. Ex: agar b. Enriched media: general purpose media is supplemented by blood or other nutrients i. Ex: chocolate/blood agar, media with soil c. Minimal media: contains minimal necessities for growth of the wild type; contains only inorganic salts, simple carbon sources, and water i. Wildtype: make all their essential for growth on their own in a natural environment – survive in minimal media ii. Mutant type: don’t make all essential necessary for growth and require some nutrients to be provided by media – cannot survive in minimal media d. Selective media: favor the growth of some microorganism but inhibit the growth of other i. MacConkey agar selects for gramnegative (contains CV and salts that inhibit grampositive bacterial growth) e. Differential media: distinguish between different groups of microorganisms based on their biological characteristics i. Blood agar differentiates between hemolytic and nonhemolytic cells 1. Alpha hemolytic cells partially break down blood and turn the plate green/yellowish 2. Beta hemolytic cells completely break down blood cells and turn the agar clear 3. Other colonies will appear tan as usual ii. MacConkey agar 1. Differentiates between lactose fermenters versus nonfermenters 2. pH indicator turns pink if acid is being produced 3. Lactose fermenters produce acid and turn plate pink 25. Define and describe a “pure culture” of bacteria, and know the techniques used to isolate one. a. Pure culture: population of cells arising from a single cell b. A mixture of cells is applied to an agar surface so that individual cell colonies are well separated from each other c. Countable plate has 30300 colonies d. Streak plate i. Spread a mixture of cells on an agar surface with an inoculating loop – cells reproduce to form colony; 4 quadrants ii. e. Spread plate i. Small volume is diluted and transferred to agar surface; culture is spread evenly with a sterile hockey stick f. Pour plate i. Diluted sample is mixed with liquid agar ii. Mixture of cells and agar are poured into sterile culture dishes (some of the colony are imbedded in the agar) 26. Describe aseptic technique. a. Flame loop b. Open tube – hold cap in pinky c. Flame top of tube d. Collect bacteria from tube e. Flame top of tube f. Replace cap from pinky 27. Be able to set up a dilution and calculate cell concentration from a plate count. 28. Describe microbial growth on solid surfaces and its significance in identifying bacterial species. a. Form: punctiform, circular, filamentous, irregular, rhizoid b. Elevation: flat, raised, convex, pulvinate Chapter 3.1 – 3.5 29. Recognize and know the cell morphologies (shapes and arrangements) of prokaryotes. a. Shape: cocci and bacilli most common b. Arrangement: determined by plane of division and degree of separation after division i. Coccispheres 1. Diplococci – pairs 2. Streptococci – chains 3. Staphylococci – grapelike clusters 4. Tetrads – 4 cocci in a square 5. Sarcinae – cubic configuration of 8 cocci ii. Bacilli – rods 1. Vibrios – comma shaped 2. Spirilla – rigid helices 3. Spirochetes – flexible helices iii. Filamentous – mycelium, network of long, multicellular filaments iv. Pleomorphic – variable in shape 30. Know the size ranges for bacteria, viruses, and eukaryotic cells. a. Eukaryotes: 0.8 um – hundred of um b. Bacteria/Archaea: 0.2um – 750 um c. Virus: 0.01 um – 1 um 31. Understand the relationship of the size of the cell and its surface area to volume ratio. a. The smaller the cell, the greater the surface to volume ratio b. Because of the increased surface area to volume ratio 32. Explain the advantages of being small. a. Advantages of increased surface area to volume ratio: i. Nutrients exchange happens faster ii. Wastes expelled faster iii. Cell grows faster iv. Cell reproduces and divides faster v. Short generation time allows better ability to adapt to changes in the environment 33. Describe the structure and functions of the plasma membrane of Bacteria and be able to label it. a. Plasma membrane structure i. Lipid bilayer composed of phospholipids ii. Amphipathic lipids 1. Polar ends – hydrophilic 2. Nonpolar tails – hydrophobic iii. Phosphate group is negatively charged which allows basic stains to bind to it iv. Saturation levels of membrane lipids reflect environmental conditions 1. More hyrdrogen makes it more saturated 2. More double bonds make it more unsaturated 3. When environment is very hot the lipid becomes more saturated so it will exist as solid in room temp 4. When environment is cold the lipids will be more unsaturated, liquids at room temp b. Plasma membrane functions i. Encompasses the cytoplasm ii. Selectively permeable barrier selects what is able to enter the bacteria iii. Interacts with external environment 1. Receptors for detection of and response to chemicals in surroundings 2. Transport systems 3. Metabolic processes a. Electron transport chain is located in cell membrane of bacteria 34. Compare and contrast the structure, composition, and functions of the cell walls of grampositive and gramnegative bacteria. Be able to label them. 35. Describe the effects of lysozyme and penicillin on a bacterial cell wall. 36. Explain how bacteria may survive without a cell wall. 37. Describe capsules and slime layers and discuss their functions. DISEASES* 38. For each of the microbial diseases listed below, be able to briefly describe the following: a. cause (name of bacterium or virus) b. general characteristics of the microbe (bacterium – Gram reaction and shape, virus – type of genome [DNA or RNA] and shape) c. route of transmission d. characteristic symptoms. Tuberculosis Bubonic Plague Tetanus Smallpox Rabies Pertussis *Even if we do not cover these diseases in class, you are still responsible for the information. UNIT 1 ANIMATIONS TO WATCH: http://highered.mheducation.com/sites/0073402400/student_view0/index.html : Chapter 3 “Procaryotic Cell Shapes” NOTE: Unless otherwise stated, you are responsible for all of the unit objectives even if they are not covered in lecture (see textbook).
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