Microbiology Notes Part 1.pdf

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MICR 2420
Emma Allen- Vercoe

Concept 1: Cells are the fundamental unit of life Concept 4: Origins of life on Earth • All cells are made up of one or more cells • All life of Earth is made of stardust, the remains of • 2 kingdoms of unicellular organisms supernovae • 3 kingdoms of multicellular organisms • Origin of life required fundamental elements that make • 2 kingdom which is a mixture of both up organic molecules Concept 2: Cell function • Life required continual energy input, and a temperature • Each living cell has the c apacity to perform certain basic range that permits liquid water functions that are characteristic of all living forms • Earliest forms of life that we know were bacteria • A cell is able to live and perform all its functions because Concept 5: Endosymbiosis of its organelles • ER and nuclear envelope of eukaryotes may have • These organelles together constitute the basic unit of life: evolved from mistaken folds of the plasma membrane in the cell a primordial cell Concept 3: Macromolecules are fundamental to all cells • Mitochondria and chloroplasts are organelles that at a • Carbohydrates – monosaccharides critical point in evolution were engulfed by host cells • Proteins – amino acids and evolved to carry out specific functionsfor them • Nucleic acids – nucleotides • Mitochondria – produce energy from chemical • Lipids – glycerol, fatty acids components • Chloroplasts – produce energy from light Founding Microbiologists 1. Antonie Van Leeuwenhoek – lenses up to 500x magnification 2. Edward Jenner – inoculation of cow pox to treat small pox 3. Louis Pasteur – swan neck flasks proved that microbes weren’t formed spontaneously 4. Sergio Winogradsky – some microbial species feed solely on inorganic minerals 5. Robert Koch – Koch’s postulates, discovered link between m icrobes and diseases 6. Carl Woese – discovered the 3 domain of life 3 Domains of Life 1. Archaea 2. Bacteria 3. Eukarya Serial Endosymbiosis Theory Mitochondria, chloroplasts, plants, algae, anamalia, fungi protists, and other organelles of eukaryotic cells orig inate through symbiosis between multiple microorganisms , originally prokaryotes. Vertical / Horizontal Gene Transfer Vertical: inheritance of a characteristic, passed down from earlier generations Horizontal: sharing of a characteristic, acquired from a n unrelated bacterium Giruses Giant viruses have very large genomes and also some enzym es are involved in translation (i.e. mimivirus). Originally mistaken for bacteria. They have no rRNA genes and tend to parasitize protozoa. Eukaryotes vs. Prokaryote s Eukaryotes Prokaryotes Large cells (>10micrometers) Small cells (<5micrometers) Perils of a prokaryote - they are subject to many stresses like: Often multicellular Always unicellular • Predation Always have a nucleus / membrane bound organelles No nucleus / membrane bound organelles • Nutrient limitation DNA is linear (proteins form chromatin) DNA is circular without proteins • Osmotic stress Ribosomes are large (80S) Ribosomes are small (70S) • Temperature/pH fluctuations. Cytoskeleton No cytoskeleton Motility by flexible waving flagella (tubulin) Motility by rigid rotating flagella (flagellum)   Cell division by mitosis / meiosis Cell division by binary fission Chemotaxis The ability of organisms to move towards or away from a specific stimulus Random walk = where runs and tumbles occur Biased random walk = chemical gradient is • Taxis = movement • Chemotaxis = movement towards a chemical stimulus present therefore there will be more runs than • Phototaxis = movement towards light tumbles • Magnetotaxis = movement towards magnets   • CCW rotation moves cell forward • CW rotation stops motion so cell tumbles and changes direction • Eukaryotic flagella is non -rigid • Prokaryotic flagella is rigid (CW and CCW) Build a Bacterium Phototrophic Specific • Thylakoids – where light dependent reactions of Mollicutes – DNA, ribosomes, cytoplasm, plasma membrane • Cell wall with peptidoglycan (murein) photosynthesis take place Gram Positive – DNA, ribosomes, cytoplasm, plasma membrane, • Carboxysomes - compartments with enzymes involved in carbon fixation thick cell wall • Strong techoic acid threads through peptidoglycan layers • Gas vesicles – allows microbe to maintain buoyancy Storage Granules – stores excess energy adding strength Magnetosomes – magnetotaxis orients itself with Earth’s • Must be kept away from lysosomes (in tears and saliva) • STAINS BLUE magnetic field Pili (fimbriae) – bacterial adhesion and motili ty Gram Negative – DNA, ribosomes, cytoplasm, plasma membrane, thin Rotary flagella – rigid and uses chemoreceptors to propel cell wall • Endotoxin (Lipopolysaccharide (LPS)) is a major constituent bacterium in optimal directions • Monotrichous – 1 flagella of the outer cell membrane • Lophotrichous – multiple flagella at 1 or both ends • STRAINS RED S Layer – bacterial chainmail • Amphitrichous – 2 flagella at opposite ends of the cell • Peritrichous – multiple flagella pointing in many Capsule – slime layer directions at many spots on the cell Mycobacterium spp.   • In exotic cell wall structure which contains mycolic acids • Infections are a health emergency, difficult to treat because they have unusual cell walls • Can be stained using an Acid Fast Bacilli (AFB) Wikimedia'commons'                   Wikimedia'commons' h>p://www.quia.com' h>p://faculty.ccbcmd.edu/courses/bio141' Archaea Wikimedia'commons' h>p://www.quia.com' Archaea Bacteria Cell membrane contains ester linkages Cell membrane contains ester bonds Cell walls lack peptidoglycan * but use a Cell wall has peptidoglycan pseudopeptidoglycan consisting of L -glycerol and isoprene 3 RNA polymerases (like eukaryotes) 1 RNA polymerase Often extremophiles Occasionally are extremophiles Resistant to most antibiotics Sensitive to antibiotics * Archaea lack peptidoglycan which is what antibiotics target, therefore they are more difficult to kill. Archaeal Extremists   • Thermophiles – high heat • Psychrophiles – very cold • Halophiles – high salinity • Acidophiles – low pH • Barophiles – high pressure Methanogens Methanogens are able to generate methane from CO , H , 2orm2te, acetate and other small molecules. The basic reaction is: CO +24H -> 2H + 2H 4 2 Viruses A virus is a noncellular particle that must infect a host cell where it reproduces. Viruses can be modified as delivery vehicles for gene therapy. Bacteriophages can be used as cloning vectors. Viruses infect the genome of the host cell and then replicates to aff ect other cells. Each virus has a host range. Each species of virus infects a particular group of host species, known as the host range. Examples of a narrow host range are smallpox virus and HIV. Examples of a wide host range are West Nile Virus and cucumber mosaic v irus. Virus structures are icosahedral, filamentous (helical), multiple helical packages, complex viruses and asymmetrical viruses. Viral genomes resemble eukaryotic mRNA, they are very simple and efficiently packaged. Viroids are extremely simple viruses, there is no protective capsid. They are usually RNA molecules that infect plants. Some have catalytic activity which can cleave very spec ific RNA sequences. Prions Prions consist of protein only, and arise from the host cell. They form an abnormal struc ture and interact with the normal form of the protein resulting in transformation to the prion form. Multiple prion
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