Microbiology Test 1 Campbell – Flashcards
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| What is microbiology? |
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| Microbiology is the study of organisms which are usually seen by a microscope, not the unaided eye. |
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| Prokaryotic vs. Eukaryotic |
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| Prokaryotic cells came into existence before the eukaryote. They do not have membrane bound organelles or a nucleus. Eukaryotic cells have a nucleus and membrane bound organelles |
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| Carl Woese |
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| He created Domain, which is used as a classification system. It showed 2 distinct types of groups, Bacteria and Archaea |
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| Prokaryotes |
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| Majority have cell wall with peptidoglycan. Reproduce by binary fission. About 0.3-5 nanometers. |
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| Significance of Cyanobacteria |
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| produces significant amounts of oxygen; photosynthetic |
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| Archaea |
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| Distinguished from bacteria by unique rRNA gene sequences. Lack peptidoglycan in cell walls. Have unique membrane lipids. Many live in extreme environments (hydrothermal vents, dead sea) |
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| Protozoans |
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| unicellular, motile, sexual and asexual reproduction ex: phytoplankton (photosynthetic) |
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| Algae |
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| unicellular and multicellular photosynthetic |
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| Fungi |
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| unicellular and multicellular Ex: yeast |
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| Multicellular Parasites |
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| Helminths- parasitic worms ex: roundworms, flatworms, flukes |
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| Are virus' considered organisms |
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| No, they are considered infectious agents |
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| Viruses |
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| Obligate intracellular agent Consists of either DNA or RNA, surrounded by a protein coat |
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| Viroid and Virusoids |
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| Consist of only RNA; no protein coat |
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| Prions |
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| consists only of protein, no DNA or RNA ex: Mad cow disease |
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| Why did RNA exist before DNA? |
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| RNA was first because it could store information and was catalytic and DNA is NOT catalytic, only a storage molecule |
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| The Endosymbiotic Theory |
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| The theory that states that mitochondria and chloroplasts were acquired to the eukaryotic cell by endosymbiosis from a prokaryotic cell. |
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| Who developed the Endosymbiotic Theory? |
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| Lynn Marguilis |
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| Why are microorganisms important for vital activities? |
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| Essential for environmental health Normal flora keeps you healthy |
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| What is normal flora? |
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| Bacteria that is good in one place but bad in another. 500-1000 species of bacteria reside in and on the body. Bacteria outnumber cells 10:1 Ex: E. Coli |
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| Why is nitrogen important for DNA? |
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| Nitrogen Fixation |
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| Why did the biosphere not work? |
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| There was too much bacteria taking up all the oxygen |
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| Antony Van Leeuwenhoek |
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| improved microscopy Increased magnification 50-300x |
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| What is spontaneous generation? |
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| the belief that living organisms can develop from non-living matter |
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| Who challenged spontaneous generation and what did he do? |
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| Fransesco Redi challenged spontaneous generation and he did this with the meat and maggots experiment |
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| Who tried to disprove Redi? What did he do? |
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| John Needham- he used broth |
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| Who disproved Neeham? |
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| Spallanzani disproved Neehams experiment because he found a flaw in it. |
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| What did Louis Pasture do? |
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| He created the S-curved flask to trap bacteria, but it still allowed oxygen in |
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| What is Koch's Postulate? |
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| 1. Present in every case of the disease. absent in healthy organisms 2. Must be isolated and grown in pure culture 3.Same disease must result upon infection of healthy organism 4.Same microorganism must be isolated again |
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| Why was gelatin an issue when doing cultures? |
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| Some bacteria eat gelatin |
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| What are some application of microbiology? |
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| Sewage Treatment Bioremediation (ex. oil) Produce useful products (ex. insulin, ethanol, amino acids, pesticides) Genetic Engineering Food (lactic acid, fermentation reactions) |
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| Rank microorganisms smallest to largest |
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| virus, bacteria, protist, eurkaryote |
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| How can viruses be seen? |
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| Through an electron microscope |
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| Resolution |
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| the ability to distinguish between separate objects |
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| Contrast |
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| light intensity difference between a sample and its background |
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| Light Microscope |
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| Any microscope that uses light |
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| Ocular Lens |
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| the lens that is looked through |
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| Objective Lens |
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| One near the slide |
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| Parfocal |
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| describes the microscope staying relatively focused as magnification increases |
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| Parcentric |
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| slide remains centered as magnification increases |
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| Bright Field Microscopy |
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| the image is darker than the background. Lenses are causing convergence. The convex lens focus the light (focal point), distance between the lens and F is the focal length |
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| Resolving Power |
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| the minimum distance between 2 objects with them still observed as separate entities. As resolution becomes better, resolving power decreases |
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| What factors impact resolutions path of light? (resolution dependent on) |
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| Quality and size of lens Oil Immersion Wavelength |
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| Numerical Aperture |
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| A measure of the cone of light entering into the objective lens |
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| Working Distance |
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| distance between the edge of the objective lens and the surface of the specimen |
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| Relationship between oil and glass |
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| They have the refractive index |
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| Wavelengths relation to resolution |
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| Short wavelengths increase resolution because they can fit where longer wavelengths cant |
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| Average wavelength for visible light |
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| about 500 nm |
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| What are stains composed of? |
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| A chromophore Charged salt- negative dye = acidic pH positive dye = basic pH |
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| Which type of dye is used as a negative stain? |
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| Acidic |
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| What do stains do? |
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| Increase visibility Accentuate morphological features Preserve specimens for future study (heat) |
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| Heat fixation |
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| The internal and external cell structures are preserved. This kills the organism, inactivates the enzymes, toughens cell structures. |
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| Simple Stains |
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| usually a basic dye, stains all bacteria the same color |
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| Differential Stains |
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| Distinguishes between different types of bacteria Gram stain and Acid Fast stain |
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| The Gram Stain |
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| Step 1: Add crystal violet, primary stain and makes everything purple Step 2: Add iodine, mordant, makes everything bigger Step 3: Alcohol Wash, decolorizes Step 4: Add Safranin, counterstain |
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| What makes something Gram+ or Gram- |
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| Gram positive indicates a thick cell wall, the crystal violet and iodine mixture is not able to escape from the thick peptidoglycan layer. The opposite is true for Gram- |
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| Acid Fast Staining |
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| Acid fast is bacteria containing numerous waxy lipids (mycolic) in their cell walls. 1. Carbolfuchion and heat 2. Decolorize by acid alcohol 3. Counterstain Methalyne Blue |
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| Special Staining |
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| Used for staining specific structure inside/outside of the bacterial cell |
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| Moellar Stain |
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| A type of endospore stain 1. Carbolfushion and heat 2. decolorize 3. Counterstain with Methalene Blue |
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| Schaeffer-Fulton Stain |
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| A type of endospore stain 1. Malachite Green + heat 2. Decolorize 3. Safranine counterstain |
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| Capsule Stain |
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| A negative stain India ink is used which is an acidic dye |
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| Flagella Stain |
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| A mordant is used to make them appear thicker |
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| Dark Field Microscope |
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| Staining not required Dark background, bright organism collects only the light reflected and refracted by the ORGANISM This is used for eukaryotic cells and larger bacteria |
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| Phase Contrast Microscope |
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| No staining is required Increases contrast by slowing down some wavelengths Good for prokaryotes Has 2 types of rings- annular: directs light around and through the specimen phase: increase the contrast of light waves by speeding them up |
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| Fluorescence Microscopes |
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| UV light source Excites fluorochromes Fluorescent dyes |
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| Confocal Microscopy |
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| Laser examines 3D objects in multiple planes by a computer Normally fluorescently stained |
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| Electron Microscopy |
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| Uses electro magnetic lenses and electrons Magnifies 10,000-100,000 times |
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| Transmission Electron Microscopy |
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| Must be used under a high vacuum because air deflects Denser regions appear darker due to more electron scattering |
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| Sample Preparation for TEM |
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| Sample must be embedded, dehydrated, soaked in plastic Negative stain is possible with TEM as well as shadowing and freeze etching |
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| TEM vs Scanning EM |
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| TEM: radiation passing THROUGH a sample SEM: electrons released from the sample SURFACE |
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| Scanning Probe Microscopes |
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| Most powerful The surface is so sharp, it can touch individual atoms |
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| Shape of a coccus bacteria |
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| Round |
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| Shape of a bacillus bacteria |
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| Rod |
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| Shape of a Spirillum bacteria |
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| wavy |
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| Shape of a coccobacillus bateria |
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| round and rod |
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| Shape of a Vibrio bacteria |
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| comma shaped, uncommon |
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| Shape of a spirochete |
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| spiral, uncommon |
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| What is a chain |
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| Cell arrangement where there is a single chain in one plane |
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| What is a packet |
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| Cell arrangement where there are 3-D clumps in two planes |
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| What is a cluster |
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| Cell arrangement where the bacteria are in several planes at random |
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| What is the composition of the cytoplasmic membrane? |
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| It is made up of a bilayer of phospholipids. It is amphipathic- there is a different chemical feature on both sides. There is also a lipid bilayer with hydrophilic heads and hydrophobic tails |
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| What is the fluid mosaic model? |
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| The word fluid tells us that the membrane is not static, it can more and adjust or else cells pop. It has LATERAL movement and rotation. Mosaic tells us it is not uniform throughout the membrane. |
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| What is flip-flop? |
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| It is a rare occurance when the fluid mosaic model moves up and down. The enzyme that makes this happen is flippase. The reason this is rare is because there is a lot of resistance from the non-polar tails to move to the other size of the cell |
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| Describe an Integral protein |
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| Goes through both sides Makes up 70-80% of protein in the cytoplasmic membrane Not easily extractable Insoluble in water Have some hydrophilic regions |
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| Describe a Peripheral protein |
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| On the inside or outside of the membrane but never both. If on the inside they are normally helping another protein and if they are on the outside they are working as receptors 20-30% Easily Isolated Soluble in Water May attach to integral proteins |
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| What is true about both a peripheral protein and a integral protein? |
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| The both function as receptors for cell signaling. Both may interact with cell wall. Both are transporters of nutrients |
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| Functions of the cytoplasmic membrane |
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| Selective Barrier Site of Transport Systems Site of Crucial metabolic processes Site for special receptors to decent environmental conditions |
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| What compounds are passive transport limited to? |
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| H2O, O2, CO2, and small nonpolar molecules |
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| Describe Facilitated Diffusion |
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| Controlled by shape, depends on a concentration gradient, less important in prokaryotes |
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| Describe the two types of active transport |
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| Primary- utilizes ATP and are uniporters Secondary- utilized gradients and are symporters and antiporters |
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| Primary Active Transport |
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| ATP Binding Cassette Transports Found in bacteria, archaea, and eukaryotes. If it is gram negative the protein will attach to the periplasm but if it is gram positive it will attach to the lipids |
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| Secondary Active Transport |
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| The proton motive force is used here which is the respiratory chain in the membrane pumps protons out setting up a concentration gradient |
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| What are the 3 types of electrochemical gradients? |
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| Uniport- 1 thing, 1 direction Symport- 2 things 1 direction Antiport- 2 things, opposite directions |
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| What are the steps of phosphorylation? |
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| PEP donates phosphate to E1, pyruvate is left over E1 is going to pass the phosphate to HPr Phosphate goes E2a and then to e2b Then it is passed to glucose E2c is the transmembrane protein to where the glucose can get in but not out without the phosphate (ex. ticket booth), Glucose + phosphate = glucose 6-P |
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| What are siderophores? |
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| compounds secreted by bacteria that scavenge for iron and facilitates its uptake. Iron is brought back to the bacteria and absorbed. |
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| Describe ABC when it comes to iron transporters |
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| siderophores sit in the periplasm once in the cell once it gets into the cytoplasmic membrane it pulls the iron into the cell against its gradient the cell releases iron from the siderophore, making it able to be used |
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| What are some environmental hardships cells can go through |
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| changes from aqueous to hot and dry Isotonic to hypertonic or hypotonic |
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| What are mycoplasma? |
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| They live in environments that are friendly to their outer membranes. They use hopanoids to deal with turgor pressure They DO NOT handle environmental changes well!! |
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| What is peptidoglycan? |
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| Strands of polysaccerides that are weaved together of the cell membrane. This is unique to bacteria. This weaving provides strength to the cell wall. A tetra peptide provides the crosslinking |
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| What are some functions of the cell wall? |
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| Cell Shape Protection Nutrition Temperature |
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| What is the backbone of the cell wall? |
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| Alternating Monomers of NAG and NAM which pack into each other in numerous layers |
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| How are NAG and NAM related to glucose? |
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| The OH is replaced with an acetyl group NAM picks up the acetyl group NAG picks up the acetyl group as well as a lactyl group |
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| Describe Gram - cell wall |
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| Has DAP Has direct D-ala binds to Dap Starts link with D-ala Very thin cell wall, about 2-3 layers Periplasm is more defined Has 2 periplasms |
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| Describe Gram + cell wall |
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| Has L-lysine Does not have a direct link. 5 glycine residues in a row connect D-ala to L-lysine. This is the peptide interbridge called penta glycine Starts link with D-ala Thick cell wall, 30 or more layers Periplasm is harder to see Does not have an outer membrane Only 1 periplasm More resistant to osmotic pressures Has teichoic and lipteichoic acids |
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| What are tehichoic and lipteichoic acids? |
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| They are anchoring compounds in a Gram + cell wall. They add additional support to keep the peptidoglycan layers toether. Teichoic is within the cell wall and lipoteichoic is between the cell wall and the cell membrane. They carry a lot of negative charge |
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| What is the LPS? |
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| The LPS is a lipid attached to a polysaccharide or series of sugars. |
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| What 3 areas can the LPS be broken up into? |
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| The lipid- disaccharide of glucosamine with 3 FA attached The Core Polysaccharide- Carbohydrates attached to lipid by KDO 0-Specific Polysaccharide- Species and strain specific |
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| What is an endotoxin? |
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| When the macrophages in the bodies immune system target the LPS, it can tear apart the lipid A from the sugar tail, and if the body doesn't handle it it is very toxic, like anaphylactic shock |
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| What is endotoxin's benefit to bacteria? |
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| It works as a protective layer It functions as virulence (survival in humans)- rise in temperature can be a better environment, breakdown of cells is food. It confers negative charge in the bacteria |
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| What is a channel protein? |
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| diffusion of small hydrophilic molecule, can be different sizes based on selective entry of differently sized molecules |
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| What is Braun's Lipoprotein? |
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| Connects the outer membrane to the cell wall. Works kind of like techoic acid. It really is focused on anchoring the outer membrane. |
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| What does the ethanol do in the Gram staining process? |
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| It dehydrates the membrane! |
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| What is glycosidase? |
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| It breaks down the cell wall of bacteria in your eye (Lysozyme). It breaks down the sugar linkages in peptidoglycan and breaks the bonds between NAG and NAM |
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| What are beta-lactam antibiotics? |
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| An example of these antibiotics is penicillin. These type of antibiotics do NOT break down the cell wall, but they prevent the cell wall from growing. This antibiotic prevents cross linking. The weakened cell wall then ruptures and falls apart. |
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| What are protoplasts? |
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| Protoplasts are Gram + bacteria that do not have a cell wall, the cell membrane of this remains in tact. Protoplasts are sensitive to osmotic changes |
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| What are spheroplasts? |
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| they are gram negative cells without the cell wall. The cell membrane and the outer membrane are still in tact |
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| What is special about the mycobacterium's cell wall? |
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| The mycobacterium have an additional layer with mycolic acids. These are anchored by arabinogalactins to the peptidoglycan layer. There can also be a capsule on this bacteria. That gives the bacteria 4 layers of protection. This is why it is so hard to treat tuberculosis. To the hydrophobic nature of mycobacterium, it will always stain gram- even when its gram+, so acid fast staining is used instead |
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| What are components of the internal prokaryotic cell structure? |
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| Storage Granules- "inclusion bodies" Organic Material Inorganic Material- magnetosomes Gas vacuoles Nucleoid Plasmids Ribosomes |
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| Why are gas vacuoles important in prokaryotic cell structure? |
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| They are important for floating. In a bacteria like cyanobacteria, the gas collects from the environment to create a gas balloon to float up and collect more energy |
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| Why are nucleoids important in prokaryotic cell structure? |
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| They are where genetic information is organized. They are generally circular geneomes comprised of just one chromosome. |
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| Why are plasmids important in prokaryotic cell structure? |
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| Plasmids are small portions of DNA that can be exchanged bacteria to bacteria |
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| Why are ribosomes important for prokaryotic cell structure? |
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| Since the ribosomes are not bound by an envelope, everything can happen at the membrane which makes the process really fast |
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| What are some components of the external structure of prokaryotes? |
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| Glycocalyx Fimbriae and Pili Flagella |
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| What is the glycocalyx? |
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| it is a sugar coat on the outside of the prokaryote. It acts like an invisibility coat and is sticky. There are 2 types: capsule and slime layer. The capsule is tightly attached and organized, the slime layer is loosely attached and unorganized. |
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| What is the function of pilli and fimbriae? |
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| Pilli- genetic exchange Fimbriae- just attachments, just kind of there |
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| What are the patterns of arrangement for flagella? |
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| Monotrichous- only one flagella on either the left or right side Amphitrichous- one flagella on both sides Lophotrichous- a tuffed piece on one or both sides Peritrichous- flagella all over |
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| What is the structure of the flagella? |
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| Basal Body --> Hook --> Filament |
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| What is the filament? |
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| It is the tail of the flagella and it coils to leave a hollor center |
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| What is the hook? |
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| The hook connects the filament to the basal body |
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| What is the Basal Body? |
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| anchors flagella into the cell wall and cytoplasmic membrane, it gives the filament the ability to move |
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| What is the difference between a flagella in gram + and gram - |
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| In gram positive there is only one set of rings (M and S), and they sit in the membrane. The hook goes through the peptidoglycan. In gram - there are two sets of rings: (M and S: P and L). The M and S sit in the membrane, the hook is attached to the outer membrane, and the P goes through the peptidoglycan and the L goes through the outer membrane |
