Study guide for Exam 1 in BISC 300
Study guide for Exam 1 in BISC 300 BISC300
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This 6 page Study Guide was uploaded by Jj Lynch on Thursday March 10, 2016. The Study Guide belongs to BISC300 at University of Delaware taught by Carlton Cooper in Summer 2015. Since its upload, it has received 48 views. For similar materials see Microbiology in Biological Sciences at University of Delaware.
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Date Created: 03/10/16
Exam 1 Study Guide Bacteria Discovery o First found by Leuwenhoek, 1673, with first microscope (animalcules) o Needham tried to use appearance if microbes in previously boiled mutton as proof of spontaneous generation Spallazani repeated experiment with covered mutton (no air) and no microbes formed. Microbes came from the air Essential structures o Cell wall o Cell membrane o Cytoplasm o Nuclear material Accessory structures o Capsule o Flagella o Pili o Spore o Spore makes bacteria more resilient, protects from heat denaturing proteins Cell envelope- plasma membrane, cell wall, capsule/slime layer Bacteria don’t have membrane bound organelles Genetic material in nucleoid region Ribosomes and larger masses are called inclusions Flagella fro locomotion Plasma membrane selectively permeable Respiration, photosynthesis, and synthesis of lipids and cell wall parts occur in plasma membrane Peripheral membrane proteins- loosely connected to membrane and soluble in aqueous solution Integral membrane proteins- insoluble in aqueous solution, amphipathic Membrane is actually a patchwork of different lipidmicrodomains Lipid composition of bacterial membrane varies with temperature o Lower temp = more unsaturated fatty acids o Higher temp = more saturated fatty acids Have hopanoids- sterol-like molecules made from same precursors as steroids, stabilize the membrane Growth Factor- molecules needed for survival, obtained from the environment Bacteria take in dissolved materials up the concentration gradient Passive Diffusion- (simple diffusion) molecules move from higher to lower concentration (down the gradient) Channels- proteins for pores for substances Carriers- proteins carry nutrients across membrane Facilitated Diffusion- movement across membrane with help from channels or carriers o Active Transport- molecules move from lower to higher concentrations through input of energy o Primary- uses carriers called primary active transporters. Energy comes from ATP hydrolysis o Secondary- uses potential energy of ion gradients to transport o Group translocation- molecule is chemically modified when brought into cell Bacterial ones are 70S, made of 50S and 30S subunits o Eukaryotic = 80S Gram Stain o 1884 Hans Christian Gram o 2 groups: Gram + and Gram – o + have thick cell wall, dye purple o – have thin cell wall, dye pink/red o Bacterial cell wall made of peptidoglycan 2 sugar derivatives (N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)) and amino acids o Cell wall provides structure and shape Survival in hypotonic environment too Ie/ what penicillin targets o Crystal violet (all purple cells) iodine (all purple) alcohol (G+ = purple G- = no color) safranin ( G+ = purple G- = red) o G + bacterium: NAG and NAM peptidoglycans alternate in cell wall (this happens in G– too) Have “chaperone proteins” called Teichoic acid, support the large cell wall Lipoteichoic acid attaches cell wall to plasma membrane o G – bacterium: Has outer membrane Lipoproteins connect cell wall to outer membrane o G – have pili and flagella, G + just flagella o Gram + and – bacteria have different Periplasmic space o Plasma membrane and the outer one (for G -) and the space between the plasma membrane and cell wall (G +) Capsule and slime layers made of polysaccharides and/or polypeptides Capsules are organized and secure Slime layers are unorganized and not secure Bacterial Shapes o Cocci- spherical o Rod/ Bacilli- rod shaped o Vibrius- comma shaped o Spirilla- rigid, spiral May have tufts or flagella at one or both ends o Spirochets- flexible, spiral internal flagella o Small size utilizes large surface area to volume ratio Otherwise need cilia or convolutions in membrane Bacterial Movement o Monotrichous-one flagellum (polar if on an end) o Amphitrichous-one flagellum at each pole o Lopotrichous- cluster of flagella at one or both ends o Peritrichous- flagella evenly spread over whole surface o Flagellum has 3 parts Filament extends from cell surface to tip, composed of flagellin, is an example of self assembly Basal body is embedded in cell envelope, most complex part Hook connects filament to basal body o Chemotaxis- movement toward chemical attractants and away from repellants o Chemical attractants and repellants are detected by chemoreceptors In plasma membrane in Gram – Oxidize sugars they come into they come into contact with o Concentrations of attractants and repellants dictate bacteria motion o Direction of flagella rotations determines whether run or tumble happens Flagella turns counter clockwise = run, clockwise =tumble o Towards repellant: tumble more, run less Opposite for away o Towards attractant: run more, tumble less Opposite for away Quorum Sensing o “Bacteria taking a vote” o Antibiotic production o Conjugation o Virulence factors o Biofilm formation o Bioluminescence Viruses and Phages o Structures Nucleocapsid: composed DNA or RNA and a protein coat (capsid) Envelope- outer and flexible membrane layer o Don’t have a cell wall o Capsids are large, macromolecular and protect DNA/RNA o Nucleic acid in virus can be DNA or RNA, single or double stranded, or have + or - polarity Virus and Phage Reproduction o Phage reproduction far more complex than virus Phage gets through cell was because it attacks bacteria o Virus and phage attaches, injects DNA, synthesis and genomes and protein, does assembly and releases o Virus can get in through membrane fusion (if enveloped) and endocytosis (if enveloped or enveloped) o Virus entry is membrane receptor mediated o Viral proteins go to plasma membrane, attract and bind to formed capsid, virus leaves through protein spot through budding o When viral genetic material enters it is replicated and the genes are expressed o Types of infection Acutecell dies when virus is released Latent (ie/ herpes) prolonged, genetic material is there but not replicating Chronic (ie/ HIV) always replicating slowly Transformation into malignant cell (carcinogenesis) o Phages: Virulent lyses host, destroys host DNA, replicates its own, synthesizes more phage DNA and proteins, assembles phages, releases enzyme to break cell wall and lyse cell No budding LYTIC PHASE Temperantphage DNA integrates into host DNA (prophage), when host replicates prophage is replicated too When host is under stress prophage goes back to phage to prepare to leave (goes to lytic phase) LYSOGENIC PHASE Bacterial Reproduction o Bacteria reproduce asexually through binary fission 1) Cell wall, membrane and volume enlarge and DNA starts to replicate 2) Chromosomes separate and septum starts to grow inward 3) Septum grows completely through center separating cell into 2 4) Daughter cells could separate completely or stay attached in chains or doublets o Have 1 circular chromosome with single origin of replication o Bacterial proteins: FtsZ is involved in initiation of septum formation MinCDE determines FtsZ and septum location by oscillating back and forth and forcing FtsZ to be in cell center MreB is involved in cell shape, coordinates cell wall rebuilding by distributing peptidoglycan o Bacterial growth curve: closed experimental environment Lag phaseacclimation of cell in environment, preparing for cell division Exponential phasebinary fission Stationary phasetoo much bacteria in population Death phasepopulation drops because it ran out of resources Long term stationary phasemost resilient bacteria left behind o Yield cell count and growth rate curves do not look the same Bacterial environment o Respond to solute activity, pH, temp. and Oxygen conc. o Halophiles-prefer salt conc. > .2M o Bacteria survive in hypertonic environment by accumulating solutes o Most bacteria prefer acidic environment Acidophiles- prefer pH 0-5.5 Neutrophiles- prefer pH 5.5-7 Alkaliphiles- prefer pH 8.5-11.5 o In response to acidity they pump H+ out and/or use acid shock proteins o Can’t regulate internal temp o Psychrophiles-prefer 0-20 degrees Celsius o Psychrotrophs- prefer 0-35 degrees Celsius o Mesophiles- prefer 20-45 degrees Celsius o Thermophiles- prefer 55-85 degrees Celsius o Hyperthermophiles- prefer 85-113 degrees Celsius o Heat shock proteins, saturated fatty acids in membrane, more chaperone proteins all help protect against heat o Oxygen is toxic by producing free radicals o Obligate aerobe- loves oxygen o Faculative anaerobe-prefers oxygen but can live without o Aerotolerant- tolerates oxygen o Strict anaerobe- hates oxygen o Microaerophile- likes a little oxygen (> than facultative) Metabolism o Hetrotrophs-use organic molecules for energy o Autotrophs-get carbon from CO2 and energy elsewhere o NADH= 3 ATP, FADH= 1 (36 total ATP in cell. Resp.) o Carbon needed to make macromolecules o Phototrophs use light to make energy o Chemotrophs oxidize chemical compounds to get energy o Lithotrophs use reduced inorganic molecules to get electrons o Organotrophs get them from organic molecules o Anabolism uses ATP, catabolism makes it o Fermentation uses organic molecule, instead of O, as final electron acceptor Alcoholic and lactic acid o 3 catabolic pathways aerobic, anaerobic, and fermentation only fermentation does not do Krebs and ETC o Chemolithotrophic respiration- oxidizes inorganic compound and electrons transferred to molecule as final acceptor
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