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what are the general structures of bacteria
- unicellular
- no true nucleus, instead nucleoid region
- small genomes with very little non-coding DNA
- 70S ribosomes
- many have plasmids
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what are plasmids
- circular molecules of DNA that are much smaller than chromosomes
- additional genes besides their core genomes
- carries non essential genes that give the cell adaptive benefits (i.e antibiotic resistance genes, virulence genes)
- bacteria can exchange plasmids by exposure to virulent bacteria
- contains genes that allow them to replicate within the cell and transfer between cells
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describe the nucleoid region of bacteria
- often contain one circular chromosome
- no histones to organize chromosome
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how is parasitic bacterial genes different than free living bacteria
- uses host cell's enzyme and nutrients
- protected from environmental stresses by host
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how are bacterial genes organized and describe its f(x)
- organized by their products
- genes that code for enzymes in the same pathway tend to be on the same operon
- all genes in an operon are turned off/on at the same time
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how do host signals (temperature, nutrients) affect virulence genes
- host signals can turn virulence genes on
- allows cells to infect hosts when conditions are right
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what is horizontal gene transfer
- "lateral gene transfer"
- occurs when bacteria are close to each other, conjugate, and share genetic information (plasmids).
- results to antibiotic resistance and virulence genes that rapidly spread through bacterial communities
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can genes be shared among cells of the same species or between distantly related species
both
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what is transduction
transfer of DNA from one bacteria to another
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what is conjugation
transferring plasmid from one bacteria to another
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Describe the bacterial cell wall
- composed of peptidoglycan (PG), which are short chains of amino acids that are cross links between sugar residues
- the cell wall is outside of the cytplasmic membrane.
- f(x): resists turgor pressure and determines cell shape
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what type of cell wall is this?
- gram negative
- thin peptidoglycan cell wall
- contains outer membrane
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what type of cell wall is this?
- gram positive
- thick peptidoglycan cell wall
- no outer membrane
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what is periplasm?
- space between the the outer membrane and inner cytoplasmic membrane
- contains transport, degradative, and cell wall synthetic proteins
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describe the bacterial cell membrane(s)
- composed of phospholipid bilayer
- contains; proteins, glycoproteins, lipoproteins, lipopolysaccharides
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where does bacterial respiration (aerobic and anaerobic) occur
cytosolic membrane
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describe the surface proteins on the cell membrane
- contains antigens that are detected by antibodies
- adhesins that help cells stick to surfaces
- metabolic enzymes that
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what are capsules
- outer most layer of some bacteria, found in both gram (+) and gram (-)
- made of polysaccharides
- is an important virulence factor
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how are capsules important virulence factors
- prevents recognition and engulfment by phagocytic cells
- protect cells from dessication, bacteriophages, detergents
- help cells adhere to surfaces, including host cells
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what are lipopolysaccharides (LPS)
- an essential part of the outer membrane of gram (-) bacteria
- an endotoxin and pathogen-associated molecular pattern (PAMP)
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how is LPS a pathogen associated molecular pattern (PAMP)
- stimulates innate immune response
- can induce fever and shock
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endotoxin activity is only found in what G +/- ?
G (-)
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exotoxin activity is onlyfound in what G +/- ?
+
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what are the types of bacterial appendages
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both flagella and pili are involved in the development of what
bacterial biofilms
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describe flagella
- very long "tail like structures tha move cells like a rotating propeller
- used primarily for bacterial motility
- flagellin proteins can be PAMP
- can extend and retract to move bacterial cells
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what is PAMP
pathogen associated molecular pattern
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what is pili
- "fimbria(e)"
- used for motility, adherence, conjugation
- often have adhesins at their ends to stick to host tissues. Attributes to virulence of pathogens
- Pilin protein can be PAMP
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describe the difference between swimming and swarming
- swimming: moving through liquid medium
- swarming: moving through semi solid or agar plate
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cells that swarm tend to have higher antibiotic resistance (T/F)
true
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describe biofilms
- communities of bacteria encased in a complex of molecular matrix
- contains exopolysaccharides, proteins, DNA
- help bacteria to stick to surfaces and resist envrionment stress (dessication, antibiotics, phagocytosis)
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what is the significance of biofilms on hospital equipment and host tissues
- hospitals: lead to drug resistant bacteria, infecting patients
- biofilm can form host tissues that make infections difficult to eradicate
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what are endospores
- "spores"
- dormant structures that form in actively growing bacterial cells in response to stress, to improve their chances of surviving that stress
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are endospores metabolically active?
no, they can survive without a source of nutrients or water
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what are some sterilization techniques that endospores are resistant to
- dessication
- UV radiation
- extreme temperature
- high pressure
- disinfectants
- antibiotics
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antibiotics prevents fast/slow pathogens?
fast pathogens
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what are some important bacteria that form spores
- bacillus antracis
- bacillus cereus
- clostridium tetani
- clostridum difivile
- clostridium botulinum
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