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The flashcards below were created by user
vanessasoto
on FreezingBlue Flashcards.
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the cell envelope
external covering outside the cytoplasm
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what are the 2 basic layers the cell envelope is composed of
- cell wall-outer
- cell membrane -inner
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what does the cell envelope do
maintain cell integrity
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gram positive bacteria
thick cell walls composed primarily of peptidoglycan and cell membrane
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gram negative bacteria
outer membrane, thin peptidoglycan layer, and cell membrane
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structure of cell walls
determines cell shape, prevents lysis or collapsing due to changing osmotic pressures
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peptidoglycan
- unique macromolecule composed of a repeating framework of long glycan (sugar) chains cross linked by short peptide (protein) fragments
- makes up bacterial cell walls
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what is the outer membrane similar to
cell membrane bilayer structure
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what does the outermost layer contain in the gram negative cell wall and what are they
- lioppolysacchardes and lipoprotein (LPS)
- which are endotoxins that may become toxic when released during infection
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what is the bottom layer composed of in the gram negative cell wall
phospholipids and lipoproteins
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what surrounds the peptidoglycan
periplasmic space
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what are gram stain
- differential stain that distinguishes cells with a gram positive cell wall from those with gram negative cell walls
- *important basis of bacterial classification and identification
- *practical aid in diagnosing infection and guiding drug treatment
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what color do gram positive turn
retain crystal violet and stain purple
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what color do gram negative turn
lose crystal violets and stain red from safranin counterstain
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atypical cell walls
- bacterial groups that lack cell wall structure (mycobacterium)
- stain gram + but are not they contain lipid mycolic acid
- some have no cell wall (mycoplasma)
- cell membrane is stabilized by sterols
- pleomorphic
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pleomorphic
having extreme variation in shape
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what is the cell membrane structure
phospholipid bilayer with embedded proteins-fluid mosaic model
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what does the cell membrane function in
- providing site for energy reaction, nutrient processing, and synthesis
- transport into and out of cell (semi permeable)
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cytoplasm
- dense gelatinous solution of sugar, amino acids, and salt
- 70-80% water
- aka cytosol
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chromosomes
single, circular, double stand DNA molecules that contains all the genetic information required by a cell
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nucleoid
a dense area where DNA is tightly coiled around a protein
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plasmids
- small circular double stranded DNA
- duplicated and passed on to offspring
- not essential to bacterial growth and metabolism
- used in genetic engineering- manipulated and transferred from cell to cell
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inclusions and granules
- intracellular nutrients storage bodies
- vary in size, number and content
- bacterial cells use them when environmental sources are depleted
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what are the 3 types of endospores
- dormant
- sporulation
- germination
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dormant endospores
- resting,cells produced by some G+ bacteria
- have two phases
- vegetative cell and endospores
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vegetative cell
- metabolically active and growing
- can reproduce in this stage
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endospore (dormant)
- when exposed to adverse environmental conditions capable if high resistance and very long term survival
- cant reproduce in this stage
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what are clostridium, bacillus and sporosarcina
dormant endospores
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sporulation
- formation of endospores
- hardiest of all life form
- withstands extreme in heat, drying, freezing, radiant, and chemicals
- not a means of reproduction
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germination
return to vegetative growth
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endospores
- thick coat
- resistant to ordinary cleaning methods and boiling
- pressurized steam and 120 C for 20-30 min will destroy (autoclave)
- produced by several bacterial pathogens
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what are the bacterial pathogens that produce endospores
- bacillus anthracis (cause of anthrax-candidate for bioterrorism) (Robert Koch)
- clostridium tentani (cause tetanus(lockjaw))
- clostridium perfringes (causes gas gangrene)
- clostrium botulinum (cause botulism, a deadly food poisoning
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what are the 3 basic shapes of bacteria
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bacillus
- rod/bacilli
- coccobacillus-very short and plump rod
- vibrio-gently curved rods
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spirillum
- rigid helix like cork screw
- spirilla
- spirochete-flexible helix, like spring, cant change form can change shape
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staphylococci or micrococci
irregular clusters
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palisades
- rods are parallel
- "Chinese letter arrangement"
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cyanobacteria
- blue and green algae
- gram- cell walls
- have photosynthetic chlorophyll pigments
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bacteriochlorophyll
- green and purple sulfur bacteria
- do not give off oxygen as a product of photosynthesis
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rickettsias
- very tiny gram- bacteria
- obligated intracellular pathogens
- cannot survive or multiply outside of a host
- cannot carry out metabolism on their own
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rickettsia richettisii
rocky mountain spotted fever
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rickettsia prowazekii
epidemic typhus
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clamydias
- tiny
- obligate intracellular parasites
- not transmitted by arthropods
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chlamydia trachomatis
severe eye infection and causes blindness in on the most common sexually transmitted disease
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chlamydia pneumoniae
causes lung infection
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archara
- aka extremophiles
- live in most extreme habitats in nature
- adapted to extreme heat cold salt acid and pressure
- contain unique genetic sequence in their RNA
- have unique membrane lipids and cell wall constructions
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methanogens
- can produce methane gas
- common in mud
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halophiles
require salt to grow and can tolerate habitats with extreme salt concentrations
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acidophiles
prefer to live in highly acidic (low ph) environments
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barophiles
can tolerate habitats of extreme pressure
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psychrophiles
- flourish a very low temps
- found in polar ice caps and snow
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hyperthermophiles
flourish in very high temps like volcanoes
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