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36 Cards in this Set
- Front
- Back
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What did Louis Pasteur discover?
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Created the swan neck flask so that air could enter flask but not contaminate substance. Air carries microbes! Also discovered the process of fermentation and rabies vaccine
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Who created the swan neck flask?
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Louis Pasteur
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What did Anton van Leeuwenhoek discover?
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He first observed microorganisms on his home made microscope and ground lenses. Observe and describe microorganisms accurately
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Who first observed microorganisms with a microscope?
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Anton van Leeuwenhoek
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What did Robert Koch discover?
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Created Koch's postulates, germ theory of disease. Proved that anthrax is a microorganism that killed animals.
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What did Joseph Lister discover?
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Microorganisms could cause disease. He washed his hands before every surgery and had less infection/related deaths.
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What did John Needham experiment with?
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He boiled broth and then sealed it, microorganisms still grew in the broth. Brought about the question as to why.
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What did Francesco Redi experiment with?
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He took raw meat and placed them in open containers using mesh as a control. Helped disprove spontaneous generation.
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What did Lazaro Spallanzani experiement with?
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He boiled broth in an already concealed container. Nothing grew in broth. Air is a vital force for microorganisms.
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How are John Needham and Lazaro Spallanzani related to their experiments?
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Needham boiled broth and then sealed it, microorganisms still grew in the broth. Spallanzani boiled broth in an already concealed container. Nothing grew in broth. Air is a vital force for microorganisms.
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Why was disproving the theory of spontaneous generation a key issue in the development of microbiology as a science?
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It sparked the debate that something else was behind the growths other than “must be from God.” Now that people knew it wasn’t God, it lead to the discovery that microorganisms created the growths.
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How does a bright field microscope work and what are its limitations?
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Made up of several mirrors and lenses. The light emitted from the scope is focused on the slide by the substage condenser. The nosepiece holds 3-5 objectives of varying magnification. Light that doesn’t hit the sample goes through a special phase ring (objective) and takes all light that did not hit the sample and shifts ¼ wavelength forward. Light that did hit sample is defracted and shifted ¼ back. Wavelengths are canceled (out of phase) and appears “black” therefore creating contrast to sample.
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What are the characteristics you would look for in the purchase of a bright-field scope?
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1000x numerical aperature. High quality resolution
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How do you calculate the limit of resolution of a bright-field scope? Why don’t we use 30X eyepieces for greater magnification?
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( ½ λ) ÷ NA
A 30x eye piece will magnify the image more but the resolution will be very poor so the image itself will be out of focus. |
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Why is oil used on the 100X oil immersion lens?
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prevent the loss of light usually reflected and refracted = close to glass index. Keeps numerical aperture the highest is can be.
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What are the important characteristics of a phase-contrast microscopy?
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Creates a black light that allows more contrast by collecting the light that doesn't go through the phase ring and shifts 1/4 wavelength forward and 1/4 wavelength backward when it hits the sample. Small phase shifts in the light passing through a transparent specimen are converted into amplitude or contrast changes in the image.
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What are the important characteristics of a TEM?
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A beam of electrons replaces a beam of light, and electromagnets replace glass lenses
Image is formed by deflection of electrons that pass through the specimen in a vacuum Darker areas of the image show that the sample is thicker or more dense in these areas A magnification of 300,000 times can be routinely obtained for many materials The microscope uses a 40 to 100 kilovolt electric charge to generate the electron beam |
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What are the important characteristics of a SEM?
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Lenses form the electron beam into a finely focused probe
Generates the image of the surface of a specimen, by analyzing electrons emitted from a specimen Can produce an image that is a good representation of a three-dimensional specimen. Specimens must be coated with a layer of conductive heavy metal (i.e. gold or palladium) A magnification of 100,000 times can be achieved for certain specimens |
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What are Koch’s postulates?
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Every infected organism must have microbe present
Take pure culture and infect healthy organism Every infected organism has to have microbe present Must re-isolate microbe and re-culture microbe and must be identical to original |
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Can Koch's postulate prove a virus causes AIDS?
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Not really: Not ethical to test, a long latency period and AIDS mutates
Kinda: All cases of AIDS have HIV but not all people with HIV get AIDS. |
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What are the steps to gram staining?
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Heat fix the water and organism mix.
Stain all bacteria with crystal violet: Purple color. 1 minute Rinse with water Stain is set with iodine, forces dye to bind to peptidoglycan. 1 minute -Decolorized with acetone alcohol. Decolorizes by how much peptidoglycan bacteria has. - Lots of peptidoglycan = hard to decolorize. Bacteria that were de-stained is re-stained with safranin: Red Color. 1 minute |
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What are the 3 domains of life?
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Eukaryota
Bacteria Archaea |
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Which domains of life have prokaryotes?
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Archaea
Bacteria |
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Name at least 3 types of new microscopes
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Confocal Scanning Laser Microscopy
Electron Microscope Scanning Probe Microscopy Brightfield Microscopy |
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Explain how Scanning Probe Microscopy works
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Scanning Probe Microscopy: 100,000,000x magnification. Small (bench top), not that expensive, low resolution and high magnification. A “visual version of a old fashion phonograph.” Image is made my measuring movement of a probe on the surface of a sample using electrical current. Takes a long time to do and surface must conduct electricity. Do not rely on light.
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What is the difference between gram positive and gram negative envelopes?
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Gram +
Has a thick peptidoglycan layer Layers help together by Teicnic acid Has a pentaglycine interbridge Plasma membrane Gram - Has 2 cytoplasmic membranes Thin peptidoglycan layer |
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How does a gram stain work?
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In gram +, the crystal violet stains the peptidoglycan layer where the iodine sets it in the layers of the cell wall. In gram -, the membrane prevents the crystal violet from taking so the safranin takes in the end.
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What is peptidoglycan?
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It's a murein sugars. The Human eye uses ‘antibiotic’ to target microbes with cell walls (human cells = no cell wall) to prevent infection. Cell wall is made of Murein Sugars, has structural strength.
-N-acetylglucosamine (G) (NAG) B 1-4 bond with N-acetylmuramic acid (M) (NAM) -B 1-4 linkage makes susceptible to split of lysozyme. -Peptidoglycan is very strong and rigid. |
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Why are fluorescent proteins useful tools in the study of prokaryotic cell structure?
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You can track organization of cell, not just a back of crap. Compartments, localization, structure, and what not.
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Describe the bacterial nucleoid.
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Lots of cheap, regulatory systems in biological systems.
Not wrapped around a histone, only in Eukaryotes. Circular DNA, contains genetic material/chromosomes. |
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Discuss the meaning of supercoiled DNA.
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One section is broken and is coiled into a supercoiled state so it’s naturally compact.
Biologically active in that state. When coils are undone it no longer works. Topoisomerases: Enzyme that regulates the supertwist |
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What is the benefit of being surrounded by a phospholipid membrane?
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Protection, compartmentalization, structure, support
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How do substances pass accross the cytoplasmic membrane?
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Water, channels, or gateways
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Compare and contrast the structure of prokaryotic and eukaryotic genomes.
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Prokaryote: Circular, more tangles
Eukaryote: Linear. Have more material. |
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What's the difference between prokaryotic and eukaryotic cells?
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Prokaryotes
No membrane bound organelles No mitochondria No Chloroplasts Have cytoplasmic membranes Have ribosomes, cell walls Eukaryotic Has nucleus Mitochondria Ribosomes are more complex chloroplasts simpler cell walls Eukaryotic DNA is linear; prokaryotic DNA is circular |
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What are plasmids? Why are they important?
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Miniature version of the chromosome. Double stranded DNA that replicate independently of the chromosome. Passed on to cell offspring. Some code for drug resistance and antibiotic resistant.
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