external appendages Flashcards
what are the two major groups of appendages
ones for motility and ones for attachment
what are two appendages for motility
flagella and axial filaments
what do flagella do
they propel bacteria + are involved in locomotion
name the 4 types of flagella arrnagements
monotrichous, amphitrichous, lophotrichous, peritrichous
define monotrichous
a bacteria has a single, polar, flagellum
define amphitrichous
one flagella at each pole
define lophotrichous
occurs when there is a cluster of flagella at one or both ends
define peritrichous
flagella are distributed over the entire bacterium
which flagella arrangement do E coli have
peritrichous
T or F: all bacteria have flagella
false; not all of them do
T or F: all spirilla have flagella
true
what percentage of bacilli have flagella
half
what amount of cocci have flagella
only a small amount
list the 3 basic parts of the flagella
filament, hook, basal body
what is the filament of a flagella + what is it’s structure
a hollow rigid shaft that extends into the environement
what is the filament of the flagella made of
the protein flagellin
what does the filament of a flagella attach to
the hook
what is the hook of a flagella in terms of structure
a short, curved, thicker segment
what does the hook of a flagella do
acts as a universal joint + allows the filament to point in different directions
what is the hook of a flagella attached to
the basal body
what does the basal body of a flagella do
anchors the hook and filament to the cell wall by means of a rod and either a series of 2 or 4 rings, depending on the cell wall structure
how many basal body rings of a flagella are there in gram neg bacteria
4
how many basal body rings of a flagella are there in gram pos bacteria
2
which part of the flagella extends into the environment
the filament
which part of a flagella acts as a joint
the hook
which part of a flagella acts as an anchorage point for the other parts
the basal body
which part of the flagella has a series of either 2 or 4 rings
the basal body
T or F: gram neg bacteria have 2 rings in the basal body of a flagella
false; they have 4 and gram pos have 2
what part of the flagella rotates to make the cell move
the basal body
how does the flagella move through the environment to move the cell
it pushes against the surrounding liquid to mediate its propulsion
where does the power to move the flagella come from
the proton motive force (PMF)
describe the how the PMF generates energy to move the flagella
bacterial ETC pumps H into periplasmic space, and those will go through the Mot protein, and that generates the energy to rotate the flagella
where does the bacterial ETC pump protons
the periplasmic space
what protein do protons go through to generate energy to rotate the flagella
the Mot protein
what types of movement are there for bacteria
runs and tumbles
which type of bacteria do runs and tumbles
ones that have mono and peritrichous flagella
describe a run
flagellum rotates counterclockwise
describe a tumble
flagellum rotates clockwise
when does a run occur
when the flagella rotate, the bacteria swims, and this is a run
when does a tumble occur
when flagella switch rotation, a tumble occurs
when will bacteria move aimlessly
when there is no attractant or repellent in the environment
describe positive chemotaxis
bacteria move towards something favorable
describe bacterial movement during positive chemotaxis
less tumbles and more runs occur
describe negative chemotaxis
bacteria move away from something undesirable
what is swarming
another type of motility – they move as a crowd
in which type of bacteria does swarming occur
in those with peritrichous flagella
describe swarming
bacteria move in unison across a moist surface
what do we see on an agar plate that has bacteria that use swarming
swarming gives distinct colony morphologies
what is an axial filament
a filament that wraps around the cell + makes it move
which type of bacteria use axial filaments for motility
spirochetes
what type of movement do axial filaments produce
corkscrew type movement
where are axial filaments located
periplasmic space
describe the orientation of axial filaments on the bacteria
they’re anchored at each end and wrap around the bacterium
what is another name for axial filaments
endoflagella
T or F: some bacteria are motile without flagella or axial filaments
true
in bacteria that move w/o flagella or axial filaments, what type of movement do they possess
twitching and gliding
describe twitching as a bacterial movement
short, jerky movements across a moist surface
describe gliding as a bacterial movement
smooth movement
in bacteria that move w/o flagella or axial filaments, what do they require to move/what mediates their movement
type IV pili and/or production of slime
what two appendages are used for attachment
fimbriae and pili
describe the basic structure of fimbriae and pili as compared to flagella
they’re shorter, straighter, and thinner than flagella
how many fimbriae/pili can there be on a cell
a few to a thousand
T or F: fimbriae and pili are found in both gram pos and gram neg bacteria
true
major function of fimbriae/pili?
attach bacterium to a solid surface, some are involved in twitching and gliding (ie type IV pili)
what do conjugation pili/sex pili do
involved in the process of bacterial mating called conjugation
describe conjugation in bacteria
the sex/conjugation pilus joins two cells together that are to undergo conjugation
describe the structure of a sex/conjugation pilus
larger and longer than fimbriae/pili
how many sex pili per cell
many bacteria can have up to 10
T or F: both gram neg and gram pos bacteria can have sex pili
false; found only in gram neg
