CHARACTERISTICS OF PROKARYOTES REVIEW
TOPICS:
- More complex than viruses but less complex than eukaryotes
- Make up most of the organic material on earth
- External: Appendates
Flagella —> “tail” that helps bacteria move around independently and hold onto
things — these make the flagella a virulent factor
single flagella = monotrichous
many flagella (polar) = lophotrichous
many flagella (non polar) = amphitrichous
many flagella surrounding prokaryote = peritrichous
Moves through space through series of runs and tumbles (move, smell,
move, smell to keep on track) towards attraction (positive (prefix)-taxis, down
concentration gradient) or away from repellant (negative (prefix) -taxis, against
concentration gradient)
ie. If an organism likes sunlight, they are positive phototaxic
and will move down the concentration gradient towards the attraction
Cocci: round, do not have flagella
Bacilli: rods, have a variety of flagella
Spirilla: spiral, usually amphitrichous but spirochetes are a tighter
spiral and their flagella located between the cell wall and outer membrane wraps around
the body making it move in a corkscrew shape
Fimbriae —> hair like bristles on the prokaryotes exterior that act as a velcro and
help it stick — this makes the fimbriae a virulent factor
Pili —> sticky external structures — this makes pili a virulent factor by itself and
can pass on virulent factors to other bacterial cells
only found in gram negative bacteria
used in conjugation = exchange of genetic material between same/very
similar bacterial species through plasmids— important to bacterial evolution
conjugation can lead to antibiotic resistance which is why hand washing is so
important especially in hospital settings
Glycocalyx —> slime layer on the exterior of the cell
thin layer - slime layer
thick layer - capsule (when performing a capsule stain, a halo will
appear around each bacterial cell indicating a capsule)
, protect against environmental stressors and hide their external
molecules that our immune system recognizes — this makes the glycocalyx a virulent factor
also helps bacterial cells stick to a vacant area, produce more
glycocalyx which attracts other microbes to that area and helps them stick and grow —>
creates biofilms
Biofilms can help the bacterial colony become antibiotic resistant and
may build up on things like catheters and pace makers which is why it’s important to
continuously clean
- Cell envelope:
Cell membrane —> all cells have cells membranes
composed of lipids and proteins
fluid mosaic model = cell membrane is semi-permeable
components —> lipid bilayer, integral and peripheral proteins,
receptors that communicate info about external stimuli, control what enters and exits cell,
and serve as attachment points for appendages that help make their movement efficient
Cell Wall —> external to the cell membrane
determine cell size and shape
not all cells have a cell wall —> mycoplasmas, contain a lot of sterols
that keep cell from lysing
made of peptidoglycan
serve to keep cell structure rigid and resist osmotic forces since many
live in aqueous environments (ie swell and shrink in fresh and salt water)
- Gram positive cells: cell wall composed of a thick peptidoglycan layer attached directly to
the cell membrane
porous
Teichoic acid (on surface and into peptidoglycan) and lipoteichoic acid
(on surface and penetrates to cell membrane) —> help maintain wall integrity during cell
division, regulate what enters and exits cell, and helps stick to host cells (virulent factor)
- Gram negative cells: cell wall composed of an outer membrane, small peptidoglycan layer,
and periplasmic space before reaching cell membrane
Lipopolysaccharides are found on the surface of the outer membrane
—> help maintain structural integrity and also block defenses that excrete toxic chemicals
— LSP is an endotoxin (virulent factor)
Lipoproteins reside on outer membrane surface —> receptors for
external stimuli
Porins reside on outer membrane surface —> channels allowing
things to enter and exit cell (effectiveness of antibiotics depends on the porin channel of the
bacteria)
Gram staining helps us see which type of bacteria and has several steps: stain slide
with crystal violet dye —> both cell walls will stain
Rinse with
TOPICS:
- More complex than viruses but less complex than eukaryotes
- Make up most of the organic material on earth
- External: Appendates
Flagella —> “tail” that helps bacteria move around independently and hold onto
things — these make the flagella a virulent factor
single flagella = monotrichous
many flagella (polar) = lophotrichous
many flagella (non polar) = amphitrichous
many flagella surrounding prokaryote = peritrichous
Moves through space through series of runs and tumbles (move, smell,
move, smell to keep on track) towards attraction (positive (prefix)-taxis, down
concentration gradient) or away from repellant (negative (prefix) -taxis, against
concentration gradient)
ie. If an organism likes sunlight, they are positive phototaxic
and will move down the concentration gradient towards the attraction
Cocci: round, do not have flagella
Bacilli: rods, have a variety of flagella
Spirilla: spiral, usually amphitrichous but spirochetes are a tighter
spiral and their flagella located between the cell wall and outer membrane wraps around
the body making it move in a corkscrew shape
Fimbriae —> hair like bristles on the prokaryotes exterior that act as a velcro and
help it stick — this makes the fimbriae a virulent factor
Pili —> sticky external structures — this makes pili a virulent factor by itself and
can pass on virulent factors to other bacterial cells
only found in gram negative bacteria
used in conjugation = exchange of genetic material between same/very
similar bacterial species through plasmids— important to bacterial evolution
conjugation can lead to antibiotic resistance which is why hand washing is so
important especially in hospital settings
Glycocalyx —> slime layer on the exterior of the cell
thin layer - slime layer
thick layer - capsule (when performing a capsule stain, a halo will
appear around each bacterial cell indicating a capsule)
, protect against environmental stressors and hide their external
molecules that our immune system recognizes — this makes the glycocalyx a virulent factor
also helps bacterial cells stick to a vacant area, produce more
glycocalyx which attracts other microbes to that area and helps them stick and grow —>
creates biofilms
Biofilms can help the bacterial colony become antibiotic resistant and
may build up on things like catheters and pace makers which is why it’s important to
continuously clean
- Cell envelope:
Cell membrane —> all cells have cells membranes
composed of lipids and proteins
fluid mosaic model = cell membrane is semi-permeable
components —> lipid bilayer, integral and peripheral proteins,
receptors that communicate info about external stimuli, control what enters and exits cell,
and serve as attachment points for appendages that help make their movement efficient
Cell Wall —> external to the cell membrane
determine cell size and shape
not all cells have a cell wall —> mycoplasmas, contain a lot of sterols
that keep cell from lysing
made of peptidoglycan
serve to keep cell structure rigid and resist osmotic forces since many
live in aqueous environments (ie swell and shrink in fresh and salt water)
- Gram positive cells: cell wall composed of a thick peptidoglycan layer attached directly to
the cell membrane
porous
Teichoic acid (on surface and into peptidoglycan) and lipoteichoic acid
(on surface and penetrates to cell membrane) —> help maintain wall integrity during cell
division, regulate what enters and exits cell, and helps stick to host cells (virulent factor)
- Gram negative cells: cell wall composed of an outer membrane, small peptidoglycan layer,
and periplasmic space before reaching cell membrane
Lipopolysaccharides are found on the surface of the outer membrane
—> help maintain structural integrity and also block defenses that excrete toxic chemicals
— LSP is an endotoxin (virulent factor)
Lipoproteins reside on outer membrane surface —> receptors for
external stimuli
Porins reside on outer membrane surface —> channels allowing
things to enter and exit cell (effectiveness of antibiotics depends on the porin channel of the
bacteria)
Gram staining helps us see which type of bacteria and has several steps: stain slide
with crystal violet dye —> both cell walls will stain
Rinse with
