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77 Cards in this Set
- Front
- Back
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three domains of life |
-domain bacteria -domain archaea -domain eukaryota |
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consist of prokaryotic organisms |
domain archaea domain bacteria |
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includes all eukaryotic organism |
eukaryotic branch |
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prokaryotes |
-in todays lab will observe -specifically bacteria -no nucleus -translates to pre-nucleus -most are unicellular -typically very small length of .5 um to 5um -great diversity -photosynthetic or non-photosynthetic -some req oxygen to survive(obligate aerobes) -while others die in presence of oxygen (obligate anaerobes) -some are faculative anaerobes -some inhibit extreme saline environments extreme cold or heat extreme acid and some can survive extreme radiation |
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unicellular |
-single celled -though some form colonies or aggregates |
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faculative anaerobes |
-they can survive in anaerobic conditions survive in anaerobic conditions but thrive in oxygenated environments |
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decomposers |
-many bacteria are this -means they consume dead organisms -recycles carbon in dead matter -bacteria consume the organic molecules in dead matter and release co2 back into the atmosphere so it can be used for photosynthesis |
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photosynthetic bacteria |
-fix co2 into sugars and release o2 into the environemnt |
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some bacteria erform |
nitrogen fixation |
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nitrogen fixation |
-incorporating N2 nitrogen gas form the atmosphere into organic molecules -needed for building nitrogen conatining biomolecules such as amino acids |
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where do prokaryotes live |
-in your intestine(aid digestion), live on skin and do nothing |
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symbionts |
-organisms tha tlive in close contact with you -can be beneficial (mutualistic), harmful(parasitic or pathogenic) or they can b neither(commensalistic) |
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some nitrogen fixing bacteria are |
-mutualistic symbionts with plant roots -supply plants with amino acids or ammonia by fixing nitrogen from the soil while th plant supplis bacteria with other organic molecules |
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pathogenic bacteria |
-are those that cause diseases -warrant the useof antibacterial products such as antiseptics and disinfectants -this is why expeiremnt for ditecting effectiveness of such products |
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cell wall |
-feature comon to all bacteria is the presence of this -provides structure for the ells and protects thecells from bursting in hypotonic environemnts much like th ecell wall of plants -diff because made of peptidoglycan not cellulose |
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peptidoglycan |
- is a rigid matieral composed of polysaccharides that are cross linked (reinforced) by short polypeptides |
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in this lab you will learn |
- abou the comp of bactieral cell walls and how th ecell wall is used to classify bacteria |
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E. coli |
-escherichia -bacterial species that is made up of harmful and nonharmul strains -mutualistic ecoli in lower intestine -help to provent growth of pahtogenic bacteria -few strains of pathogenic E. coi whic r responsible for food poisining |
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O157:H7 |
-can cause diaherra -dangersous type of E. coli -produce one or more kinds of toxins called shiga toxins |
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shiga toxins |
-can severly damage the lining of your intestines and kidneys -these bacterias are called shiga toxin-producing E. coli(STEC) |
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STEC |
-often causes bloody diharea and can lead to kidney failure in children or in ppl with weakend immune systems |
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most common contaminated foods and liquids that have caused e coli outbreaks |
-undercooked or raw burgers -salami -produce such as spinach,lettuce,sprouted seeds -unpastuerized milk, apple juice or cider -contimainated well water or surface water frequented by animals |
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STEC can also occur in |
-hand wahsing bad infected animal or animal waste -hand washign after contact with infected person -swallowing unchlorinated or underchlorinated water inswimming pool contimated by human feces -swimming water with even low levels of sewage contimation -contaminated food wateror ice |
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we use |
-the ecoli HB101 strain -safer -will use steril techniques in lab |
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overuse |
-of antimicrobial products can be dangerous |
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natural selection |
-the process which individuals with certian traits leave behind more offspring than indiviudals with other triats -select for particualr genes tht inatctive antibaterial products |
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if there is some randeom mutation in the bacterial DNA |
-that allows for resistance to antibacterial products the use of these products will select for cells with that mutation -these cells wil replicate in far greater numbers thatn non resistant cells -over many generations the entire population of bacteria will be made up of antibacterial resistant cells |
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disc-diffusion method |
-used in this study -study the efficacy of the products on curbing bacteria growth |
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disc-diffusion method relies on |
-the principle of diffusion -the molecules in the product will difuse out of the paper disc |
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-the molecules are most concentrated |
near the disk and least away |
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if a low cocentration of the product is able to inhibit bacterial growth |
-you will see a large zone of non grwoth around the disc |
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zone of inhibition |
-the clear zone on disc -the larger the zone of inhibition the more effective the product is at inhibiting bacterial growth |
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first off |
-set up bacteria plates to test the degree to which the products can inhibit bacteria growth |
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next week(this week) |
-will view and analyze the plates to determine which products are effective in reducing bacterial grwoth by measuring and recording the zone of inhibition |
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antiseptics |
-what we are testing the effectiveness today -are products used on living tissue |
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disinfectants |
-products used on inanamate objs |
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will use |
-LB nutrient rich agar plates -70%ethanol |
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standard deviation |
-after calculate the average zone of inhibition for each quadrant -a measure of the variation in your measurements -a calcution of the average amount that your individual measurements differ fromteh mean(average) of the measurements |
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to calculate standard deviation |
-subtract the mean for each individual measuremnt- this is called the deviation -square each deviation (d squared) -take the sume of d squared values- tis is known as the sum of the squares (SS) divide this sum by the number of measurements collected (n). SS/n is called the variance -will take the square root of the variance-this will give ou the standard deviation |
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bacterias small size |
-complicated classifying and studying them |
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through use of electron microscope and genetic analysis using modern molecular techniques |
- we have jsut begun ot appreciate in the past few decades the variety and complexity of the prokaryotes |
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they have reisded on earth for at least |
3.5 billion years( 2 billion years longer than eukaryotes) |
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bacteria few basic shapes are |
-spherical coccus -rodshaped bacillus -spiral |
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spherical coccus |
-plural cocci meaning berries -usually round can b oval -elongated or flattened on one side -wen divided to reproduce th ecells can remain attached to one another |
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cocci that remain in pairs after dividiign are called |
-diplococci |
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those that divide and remain attached in chainlike patterns are called |
streptococci |
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cocci that form grape-like clusters are called |
staphylococci |
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bacilli |
-divide ony across their short axis so tere are fewer groupings of bacilli than of cocci -most appear as single rods |
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diplobacilli |
-appear in pairs after division |
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streptobacilli |
-occur in chains |
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some bacilli |
-look like straws -other have tapered ends like cigars -others are oval and look like cocci that they are calle coccobacilli |
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bacillus has |
-two meanings in microbiology -as we used it refers to bacterial shape -when capitalized and italicized refers to specific genus( ex bacterium bacillus anthracis is the causitive agent of anthrax) |
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spiral shaped bacteria |
-the "other" shaped bacteria -will see spiral shapes inlab today |
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size of bacteria |
1 um -use 1000X magnification |
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ocular lenses |
-magnify images by 10X |
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obj lenses |
-vary |
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to view 1000X magnification |
-will need to use the 100X obj -req the oil immersion technique |
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gram stain |
-developed in 1884 by the danish bacteriologist Hans christian Gram -most useful becuz it classifies bactieria into two large groups -gram-positive, gram-negative based on their cell wall characteristics -not universally applicable becuase some bacterial cells stain poorly or not at all -most conisitant when used on young growing bacteria |
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a cell is gram positive if |
-it hsa thick layger of peptidoglycan in the cell wall |
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gram positive cells take in |
-crystal violet dye and stain bluish purple |
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gram negative cellls have |
-a thin layer of peptidoglican in the cell wall -an outer lipopolysaccharide layer which makes a more complex cell wall |
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gram negative cels dont retain |
-crystal violet dye and would be colorless if they were not counterstained |
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counterstain we will use |
-safranin which will stain the gram negative cells pink |
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gram reaction of bacterium can |
-provide valuable info for the treatment of disease |
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gram-positive bacteria |
-tend to be killed easily by penicillin and cephalosporin antibiotics |
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gram negative bacteria are generally |
-more resisitant becuz the antibiotics cant penetrate teh lipopolysaccharide laer -some general antibiotics such as ampicilin tha target both gram positive and negative bacteria |
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four chemicals solutions used in gram stain technique |
-crystal violet, iodine, alcohol, safranin |
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crystal violet |
-simple stain that will stain all the cells bluish purple |
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iodine |
-is a mordant that will help the crystal violet stay in the cell wals of tehe gram postie bacteria |
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a mordant |
-is a substance used in dyeing to fix the coloring matter -her ethe iodine combines with the crystal violet dye and forms large water insoluable colored compounds inteh cell wall |
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the purpose of using alc during the gram staining procecdure |
- is that it is a decolorizer -for gram positive bacteria the cell wall will dehydrate and the pores will shrink- the crystal violet trapped in the cell wall and thecell reamins violet -for gram neg bacteria -the lipopolysaccharide layer will b removed by the alc and this thin peptidolglycan layger willnot be able to retain crystal violet . as the crystal vioelt is removed the cells bcome colorless |
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safranin |
-simple stian tha twill stain the gram neg cells red -this stain does not effect the gram pos bacteria which will remain violet |
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crystal violet |
-30secs regnat used -gram pos will look violet , gram neg same |
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iodine |
-1 min -violet violet |
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alc (decolorizer_) |
-usign aprox 2mL, violet, clear |
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safranin |
-1 min -violet, redish pink |
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microscope use |
-begin viewing under 4 X obj mag(short yellow obj.) -look for colored smear9 either pink or purple0 and bring to focus -incrose to 10X obj focusing agian with fine focus knob -switch to 40X obj bring the colored speack into sharp focus using the fine focus knob must b in sharp focus -fotate the 40X obj slightly oout of way so that you can place a small drop of oil on slife -roatat 100X obj into postiion so almost touches slide and becomes immersed in the drop of oil as it locks into place |
